EPA 600/5-74-021
February 1974
Socioeconomic Environmental Studies Series
Carrying Capacity in Regional
Environmental Management
\
Office of Research and Development
U.S. Environmental Protection Agency
Washington, D.C. 20460
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and appli-
cation of environmental technology. Elimination of traditional grouping
was consciously planned to foster technology transfer and a maximum inter-
face in related fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the SOCIOECONOMIC ENVIRONMENTAL STUDIES
series. This series includes research on environmental management, compre-
hensive planning and forecasting and analysis methodologies. Included are
tools for determining varying impacts of alternative policies, analyses of
environmental planning techniques at the regional, state and local levels,
and approaches to measuring environmental quality perceptions. Such topics
as urban form, industrial mix, growth policies, control and organizational
structure are discussed in terms of optimal environmental performance.
These interdisciplinary studies and systems analyses are presented in forms
varying from quantitative relational analyses to management and policy-
oriented reports.
EPA REVIEW NOTICE
This report has been reviewed by the Office of Research and Development,
EPA, and approved for publication. Approval does not signify that the
contents necessarily reflect the views and policies of the Environmental
Protection Agency, nor does mention of trade names or commercial products
constitute endorsement or recommendation for use.
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EPA-600/5-74-021
February 1974
CARRYING CAPACI TY IN REGIONAL
ENVIRONMENTAL MANAGEMENT
by
A. B. Bishop, H. H. Fullerton, A0 B. Crawford,
M. D. Chambers, and M. McKee
Grant No. 802444
Program Element 1HA098
ROAP/TASK 21 AKL-22
Project Officer
Dr. Martin J. Redding
Washington Environmental Research Center
Environmental Protection Agency
Washington, D.C. 20460
Prepared for
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $2.65
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ABSTRACT
This report examines the concept of carrying capacity in the context
of regional environmental management. Historically, the notion of
carrying capacity developed out of descriptions of the growth and
dynamics of natural populations, and as such has been used as basis
for range and forest management practices. Applied to human
activities, however, the concept of carrying capacity must be broadened
to include the complex relations among resources, infrastructure and
productive activities, residuals, and societal preferences for quality
of life within both the natural and human environments. Four dimen-
sions of a human oriented carrying capacity--re source/production,
environment/residuals, infrastructure/congestion, and production/
societal relations--are described within normative and operational
definitions of carrying capacity. Carrying capacity is then viewed
from the standpoint of resources, regional structure, and regional
models to see how it fits within the theoretical and analytical con-
siderations related to these areas. A carrying capacity-based planning
process is described where the forces for change in the region are
analyzed in terms of impacts on identified carrying capacity indices
and compared with desired levels to pinpoint areas in which capacities
have been exceeded. The process contains an overview of how models
can be linked and integrated in order to provide information on carrying
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capacities and trade offs. Consideration in applying carrying capacity
concepts in local/urban planning are discussed, including identification
of regional driving forces, resource analysis, capacity impacts of
future change, and formulation and analysis of management strategies.
iii
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CONTENTS
Page
Abstract ii
List of Figures vii
List of Tables ix
Acknowledgments x
Sections
I Conclusions 1
II Recommendations 3
III Carrying Capacity: A Perspective For
Environmental Management 5
Growth and Carrying Capacity —
Introduction and Overview 5
Ecological Systems and Carrying
Capacity 13
Problems in Defining Carrying Capacity
Dimensions 25
Carrying Capacity—A Human Oriented
Definition 29
IV Resource Description and Carrying
Capacity 36
Resource Classification and Characteristics 36
Resource Capacity Consideration 47
iv
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CONTENTS (Continued)
Section Page
Summary 52
V Regional Structure and Carrying
Capacity 54
Introduction 54
Spatial Context for Examining Regional
Carrying Capacity 55
Regional Economics and Carrying
Capacity 59
Regional Growth and Carrying Capacity 64
Summary 69
VI Carrying Capacity in Regional Modeling 70
Regional Models and the Environment 70
Input-Output Based Models 71
Simulation Models 78
Externality Models 90
Other Modeling Approaches 95
VII A Carrying Capacity Planning Process for
Regional Environmental Management 98
Introduction 98
Specifications for Carrying Capacity-
Based Planning Process 99
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CONTENTS (Continued)
Section Page
Conceptualization of a Carrying
Capacity Planning Process 104
The Carrying Capacity Planning Process
and Environmental Management 124
VIII Applying Carrying Capacity in a Local
Urban Setting 126
Carrying Capacity in Planning
Activities 126
Carrying Capacity: Two Examples
of Regional Planning Response 151
Summary 15 7
IX References 158
References Cited 158
Other References 162
vi
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LIST OF FIGURES
Figure Page
1 Schematic diagram of residuals generation 10
2 Population carrying capacity 17
3 An example of a system with a stable equilibrium in
which stability is possible within distinct boundaries 22
4 Second-order quality states as regions of second-
order of ecological state space 22
5 Elements of carrying capacity 31
6 Flow diagram for an operational definition of carrying
capacity 34
7 Environmental-resource relations 37
8 Resource systems in regional structure 38
9 Flow of resource from and to the natural system 43
10 Relation of supportive and assimilative capacities 48
11 Activity interactions and carrying capacity 48
12 Overview of resource-carrying capacity relationships 53
13 Schematic diagram of residuals-environmental
quality planning model 74
• *
VII
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LIST OF FIGURES (CONTINUED)
Figure Page
14 Schematic outline of RFF model 76
15 Regional environmental systems model 81
16 REGMOD program flow 85
17 Flow diagram of the Arizona model 87
18 Conceptual form of state of the system model
(Williams and House, 1973) 89
19 Model procedural flow (Williams and House, 1973) 91
20 Urban cost and product curves 95
21 Representative of the carrying capacity planning
process 107
22 Relation of modeling and analytical techniques for
carrying capacity 111
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LIST OF TABLES
Table Page
1 CONSIDERATIONS IN RESOURCE CLASSIFICATION 40
2 DESCRIPTIONS OF REGIONAL INFRASTRUCTURE 45
3 DISAGGREGATION OF THE 'ECONOMIC
OPPORTUNITY "SOCIAL GOAL INTO SOCIAL
INDICATORS (TECHCOM) 120
4 RENEWABLE OR FLOW RESOURCES 130
5 NONRENEWABLE OR STOCK RESOURCES 131
6 UTAH PER CAPITA INCOME AND NET
MIGRATION 1960-1972 146
7 CONTROL MECHANISM AVAILABLE TO POLITICAL
INSTITUTIONS 149
IX
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ACKNOWLEDGMENTS
The authors wish to acknowledge the helpful participation and con-
tributions to the research of Calvin W. Hiibner, W. Cris Lewis,
Cyrus M. McKell, and Richard E. Toth of Utah State University.
Appreciation is expressed to Dr. Martin J. Redding, Environmental
Studies Division, EPA, for his support and useful suggestions as
Project Officer, and to Dr. Peter House, Russell Fitch and Ted
Williams for their cooperation in providing information and direction.
Also acknowledged is the cooperation and assistance of a number of
practitioners and students of regional planning whose participation in a
workshop during the early stages of the project was most useful in
defining issues, problems, and research directions. Workshop
participants were Paul Benson, Pacific Northwest River Basin
Commission; Perry Brown, Department of Recreational Resources,
Colorado State University; Leland Christiansen, Director, Bear Lake
Regional Commission; David Freeman, Department of Sociology,
Colorado State University; Douglas Gordon, Environmental Consultant,
F. F. Slaney and Company; Tom Mierzwa, 'Environmental Studies
Division, EPA; Lee Kapoloski, Office of the Utah State Planning
Coordinator; Walter J. Monasch, Director of Planning, Santa Cruz
County, California; Roy A. Paul, Office of State Planning, North
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Carolina; Martin J. Redding, Environmental Studies Division, EPA;
S. Thyagarajan, Executive Director, Capitol District Planning
Commission, Albany, New York; Bill Toner, American Society of
Planning Officials; and Robert Twiss, Department of Landscape
Architecture, University of California, Berkeley.
XI
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SECTION I
CONCLUSIONS
The general conclusion of the study is that the concept of carrying
capacity has appropriate application in regional planning setting. How-
ever, the concept must be broadened to include the interaction of human
and natural environments.
As a basis for regional environmental management, carrying capacity
should not be interpreted as referring simply to the number of people
that a given resource base is capable of supporting under certain speci-
fied conditions. Rather, regional carrying capacity must have reference
to the interrelated capacities of (1) resources to support productive
processes, (2) processes to supply essential goods and services, and
to provide acceptable quality-of-life levels, (3) infrastructure resources
to distribute materials and goods and services efficiently, and (4) envi-
ronmental media to assimilate the wastes generated from productive and
consumptive activities and remain within acceptable quality levels.
As a planning concept, carrying capacity has a normative dimension,
reflected by the requirement that the outputs of production--goods and
services, on the one hand, and wastes and residuals, on the other--
conform to established standards or norms; and a descriptive dimension,
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reflected by the requirement that carrying capacity conditions be
measured and related to these norms.
As a basis for regional environmental management, carrying capacity
should be viewed in the context of a planning process oriented toward
the task of formulating policies and programs for managing areas of
induced change and development.
As an objective for regional modeling, the use of carrying capacity as
a framework for utilizing a range of multiple modeling and analytical
techniques will lead to more fruitful results than attempting to develop
a single carrying capacity model. This conclusion is prompted in part
by the need to provide analysis at various scales of spatial and temporal
resolution.
A general carrying capacity-based planning process is formulated to
develop and support these conclusions.
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SECTION II
RECOMMENDATIONS
The following recommendations generally apply to the use of the carrying
capacity concept in regional environmental management and to its
further development as a regional planning tool.
For application in a regional setting carrying capacity should
be a multidimensional concept oriented to both the human and
natural environment and not a. narrow single-number concept of
population carrying capacity.
Regional carrying capacity analyses should be used within an
alternative futures planning mode as a means of examining the
impact of exogenous forces on a region.
Carrying capacity analyses should draw upon and appropriately
modify and/or synthesize disciplinary models that are already
operational and tested, rather than rely on the development of a
single carrying capacity model.
Indexing techniques which convey carrying capacity information
to decision and policy makers need to be developed.
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Additional research should be undertaken to formulate carrying
capacity limits or ranges, and the feasibility of basing these
limits or ranges on resilience measurements should be studied.
The carrying capacity-based planning process described herein
should be applied and tested in an actual planning context.
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SECTION III
CARRYING CAPACITY: A PERSPECTIVE FOR
ENVIRONMENTAL MANAGEMENT
GROWTH AND CARRYING CAPACITY--
INTRODUCTION AND OVERVIEW
Carrying Capacity; Interaction of
Natural and Human Environments
The capacity of natural and human environments to accommodate or
absorb change without experiencing conditions of instability and atten-
dant degradation is a significant concern in view of current trends of
urban growth and development. Indeed, it appears that the ability of
the environment to sustain particular levels of activity may already
have been exceeded in some areas, and in others resource management
options are rapidly being foreclosed.
Recognizing that the quantity, productivity, and regenerative capacity
of a region' s resources are limited, a strong motivation exists for a
conceptualization of environmental carrying capacity as a basis for
regional planning and evaluation. Scarce resources must be managed
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in the context of many competing demands, and the natural and human
environments must withstand perturbations caused by changes in man1 s
social and economic activities.
The Human Environment--
Viewing the term human environment broadly as man' s surroundings
created through his manipulation and use of resources, it can be fairly
said that the basic goals that have been sought in structuring the human
environment are growth oriented. Individual expectations and institu-
tional structures assume and often require growth (Cooper and Vlasin,
no date). Growth, as reflected by increasing flow rates of materials
and energies, places ever increasing demand on the production and
assimilation capabilities of resources in the natural environment.
Examples of ecological problems stemming from resource demands
are reflected in both the urban and rural systems (Bahr et al. , 1972).
Man has achieved very high productivity in rural-agricultural systems.
However, the efficiency of production is a result of a tremendous
energy cost required in order to stabilize the system. Two expensive
ways in which man asserts his own idea of stability are through
irrigation to stabilize effects of periodic drought and application of
pesticides to stabilize pest outbreaks; each is only partially success-
ful. Other energy and environmental costs include not only direct costs
s
such as mining and supplying nutrients to the soil, fabricating farm
machinery, but also indirect or unanticipated costs such as depletion
of groundwater resources at a greater rate than they are being replen-
ished or accelerating the flow of nutrients through crops with potential
costs to future generations from eutrophication of water bodies.
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The urban-industrial system can act to either accelerate or inhibit
energy flow through the ecosystem. Wherever urbanization has contri-
buted limiting nutrients to the ecosystem, productivities may be stimu-
lated. On the other hand, toxic by-products of industrialization (heavy
metals, various organic compounds, acids, radioisotopes, etc.) usually
inhibit productivities and limit diversity in natural systems. Urban-
ization also tends to concentrate wastes in relatively restricted parts
of the ecosystem. Over time, these wastes are eventually dispersed
throughout the ecosystem and ecosphere. However, immediate concen-
trations are often dangerous, and such localized concentrations give
warning of what might happen to all resources in the future if present
rates of waste disposal are continued.
The Natural Environment--
The natural environment represents a constraint on the human sector
as a function of the rates at which it can produce raw material and
assimilate residuals and wastes. The rates and capacities of the
natural environment are fixed by evolutionary processes and are fitted
to past environmental situations, not to future demands.
A certain rigidity of the natural environment is implied by the term
"constraint. " The natural environment has the capability of producing
a certain output flow of products and assimilating a certain input flow
of waste products. These processes can take place without disruption
of the integrity of the natural community provided that boundary con-
ditions are not exceeded. The magnitude of these transformation
capabilities depends on the environmental conditions and the stage of
ecosystem development or succession (Cooper and Vlasin).
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Likewise, elasticity is as much a property of natural environments as
are constraints or limits. Here the question is that of how much an
ecosystem can be manipulated without "major" change. Stresses
imposed on parts of an ecosystem, as with physical systems, are
shared with other parts of the system. Many stress-relieving cycles
are built into the ecosystem, which like other systems, appear to
follow Lie Chatelier1 s principle; i.e. systems will tend to compensate
for stress.
Constraints define the stress limits within which the system will still
return to its original condition. Whether man can relax these con-
straints in an ecosystem by ecological engineering or not is still an
open question (Cooper and Vlasin). A basic problem is in recognizing
and quantifying the magnitude of the ecological resource and identifying
what proportion of the potential is committed to the base line demands
imposed within the natural environment itself. The level of augmenta-
tion in structuring the human environment will thus be interdependent
with the existing demands of the natural environment. Recognizing
these capacities, the human sector must either be uncoupled from the
natural environment (which is not feasible at present) or it must be
reoriented to operate within the constraints of the "natural" sector or
else further evolution of the natural system is forced.
Growth and Carrying Capacity
Virtually every urban center as well as natural ecosystems, is faced
with problems of accommodating some degree of future growth and
development. The evolution of our current demographic structure in
8
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the United States is the result of a variety of powerful economic and
resource factors (Bahr et al., 1972). Factors influencing development
were ready supplies of raw materials, water and cheap power, and
cheap transportation (e.g. , coastal areas, large rivers, or the Great
Lakes).
Cooper and Vlasin note that the differences in spatial distribution of
activities between natural and human environments are "the result of
systematic responses to two selection processes (evolutionary versus
economic) that are both rewarding efficiency but under different time
domains and resource constraints. This difference lies at the heart
of the conflict between economic growth and development versus
environmental quality and stability. "
Relation of Economic and Ecologic Systems--
Economists have aptly described the problems arising out of conflict
in the progression of natural and human systems. The manifestations
of this conflict appear in widely varying aspects that have been labeled
"pollution. " The problem of pollution arises out of two related
aspects of economic activity, congestion and residuals.
Congestion is a problem that environmental and human resources have
in common. Bower (1971) describes this for ecological systems as
follows:
In a low-density or economically undeveloped setting,
an additional user of the natural environment may well
impose essentially no cost on other users. As the density
of development and the level of output increase, in the face
of finite environmental resources, each additional user will
impose additional costs associated with congestion on other
9
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users. This condition is termed an "externality" by
economists--that is, the additional user does not take into
account the costs he imposed on others in his decision to
use a common property resource. Because there are no
prices on the services rendered by the environmental media
and since they cannot be exchanged between buyers and
sellers in a market context, the price mechanism in a market
economy is not effective in limiting the use of environmental
resources.
The failure to consider the finite assimilative capacity of the environ-
ment leads to excessive use or congestion of the natural systems.
Obvious parallels are present in the human environment particularly
with public infrastructure resources such as freeway congestion at
peak hours.
Disposition of residuals, or wastes from production and consumption
activities, .follows directly as the second major aspect of the pollution
problem in environmental management. Figure 1 depicts this in
graphical form. Production activities generate residuals and wastes
which are discharged to the environmental resource base, and likewise
Residuals/
Wastes
Resources
Production
Supply
Demand
C onsumption
Figure 1. Schematic diagram of residuals generation.
10
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consumption goods themselves produce or become residuals and are
imposed on common pool resources as externalities. As Bower (1971)
puts it: "All production and consumption activities utilize the assimi-
lative capacity of the land, air, and water environments. While the
services render by these environments are essential inputs into these
activities, traditionally, no prices have been placed on these factor
inputs. Hence, far more of them have been used than would be the
case if the damages stemming from their use were properly taken
into account through pricing. " Extending this point, prohibiting the
discharge of all residuals into the environment is in effect assigning
an infinite value of pristine environmental quality. This would make
the production of goods and services impossible since no production
process is totally efficient, i. e. all production and consumption
produces some residuals.
The following example also serves to point out that pollution is socially
determined as well (Cooper and Vlasin):
If one wants a trout stream and observes a trout stream,
the stream is not polluted. If one wants a carp stream and
gets a carp stream, the stream is not polluted. However, if
one wants a trout stream and is forced to accept a carp
stream then the environment is degraded and the stream is
considered polluted. Biologically, a carp stream can be
managed as a viable biological system, if that is the desired
goal.
The basic problem stems from the lack of any mechanism
to enable a local region to converge on a single set of trade-
offs between resource utilization and environmental quality.
11
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Carrying Capacity; Economic and
Environmental Synthesis--
While economic constraints and efficiency have been the key determi-
nants of regional growth in the past, these considerations now must be
balanced by consideration of natural systems. Environmental con-
straints imposed by the ecological characteristics of any given region
should be equally influential in determining the density and distri-
bution of population, industry, agriculture, transportation and utility
services, and the location of housing.
Using the description of Koenig and Tummala (1972):
Each component of the natural environment--viz., lake,
stream, airshed, terrestrial region, etc.--is considered to
have a limited capacity for processing restricted classes of
man-made materials and energy, depending upon the "quality"
of the environmental component to be maintained. From an
engineering design perspective, these limited capacities
represent ecological constraints against which the techno-
logical and spatial features of man-made processes in
agriculture and industry and human habitats must be designed.
From an economic point of view they represent potential
constraints on regional economic developments; and from
an ecological point of view the mass-energy features of the
production-consumption processes of the economy must be
in dynamic equilibrium with a heterogeneous pattern of
biological communities as a closed ecosystem.
Thus in managing the environment for quality regional growth, questions
related to carrying capacity of environmental resources lie at the heart
of the problem of finding socially acceptable systems which are also
economically viable. These involve decisions related to types of raw
materials for use in production processes, acceptable types of product
outputs, pricing policies relating to residuals discharges, spatial
location of economic activities, desired levels of environmental quality,
12
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methods for handling residuals (such as requiring specific levels of
"waste treatment" rather than specifying a permitted quantity of dis-
charge or establishing an effluent charge on each unit of residual dis-
charge), and the time and spatial variations of assimilative capacity of
various environmental media.
In approaching these questions, Bower (1971) indicates that "decisions
and choices within the environmental sector are linked to decisions
and choices in other sectors of the economy. Just as there are limited
environmental resources, so there are limited human and capital
resources. " Carrying capacity as an environmental planning and
management tool must explicitly recognize this allocation problem and
seek to articulate the multiple trade offs among societal values involved.
Boulding (1973) puts these ecologic-economic carrying capacities in
perspective with the following comment:
Today, ecology rather than economics seems to be taking
on the role of the dismal science. All the dismal theorems,
however, merely amount to saying that there are limitations.
If these limitations are recognized and accepted, and organized
action is directed towards them, there is no reason why they
should be fatal. If we have, in fact, exceeded the human
carrying capacity of the earth (and it is by no means clear
that this is so), we will certainly have a rough time getting
back to that capacity. There seems to be no inherent reason,
however, why, once it has been achieved, a "spaceship earth"
should not be both stable and reasonably agreeable.
ECOLOGICAL SYSTEMS AND CARRYING
CAPACITY
The idea of carrying capacity was developed historically in connection
with the study and description of the growth and dynamics of natural
13
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populations. Because of its historical origin, the term carrying capac-
ity is generally thought of as population carrying capacity, a single
number which is the population limit on a species in a given ecosystem
or habitat.
The well known Malthusian equation describing population growth
dN .__
— = kN
leads to the description of population growth as an exponential equation
N = N e^
o
in which N is population size, NQ is the initial population, and k is
the growth rate per time period, t. The exponential growth model, of
course, approaches no upper bound or population limit.
Population Carrying Capacity
The earliest equation for population growth that recognized limits of
growth due to "carrying capacity" of the environment was proposed by
Verhulst in the 18th century (Deitchman, 1972). The equation
= (k-AN)N-
at
leads to the logistics growth curve
k
N =
/> -,
(A- ce )
in which N is population size, k is population growth rate, A is a
density dependent population coefficient, and c is a constant of
integration. The solution approaches the asymptote N = k/A after
14
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an initial exponential increase. The model does describe a number of
biological and economic phenomena but it is highly sensitive to the
values of the constants used.
The carrying capacity concept first received significant formal treat-
ment in the form of a set of logistic growth equations developed by
Lotka (1925) and Volterra (1926). The Lotka-Volterra equations are
a set of coupled differential equations of the form:
dN. r.N.
~dT = K.
m
K. - N. - S a. N. N.
in which r. is the growth rate of the i population, N. is the size
J.-L * 1
of the i population, K. is an upper limit on, or the carrying capac-
th *
ity of the i population, and a. is a coefficient which represents
tVi
the effect of such things as predation, competition, etc., of the j
population on the i population. The Lotka-Volterra equations were
originally purported to describe the change in the size of natural
populations which (1) are in contact with one another, and (2) have an
upper bound or limit on population density. This upper bound on
population density was called the population carrying capacity (K), and
was thought to be the result of density dependent negative feedback
resulting from such things as resource shortages, disease, predation,
etc., triggered by high population density.
The idea of a limit or upper bound on population density has been used
for some time as a conceptual tool in the management of natural
communities. Given a particular population living in a particular
habitat, the carrying capacity or upper bound on population density
for that population has generally been defined as the maximum
15
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population density which can be supported by the habitat without irrepa-
rable degradation of the habitat.
As populations are managed over time, and as the size of the managed
population approaches the carrying capacity of the habitat, any one of
three events might occur, as illustrated in Figure 2: (1) Management
practices and natural controls on the quantity and quality of resources
might limit the population near the carrying capacity; (2) management
practices aimed at the removal of some population constraints might
allow the population to exceed the carrying capacity, thus causing a
degradation of the resource base and a long-run population decline to
levels compatible with new quality levels of the resource; or (3) improve-
ments in technology or management practices might change the habitat
sufficiently to increase the carrying capacity for the population and
thus allow the population to expand without environmental degradation.
The sustained yield concept is related to the notion of carrying capac-
ity. From the standpoint of the management of biological communities,
carrying capacity describes the biological or physical relationship
between a given resource stock and its maximum sustained yield.
Specifically, it is interpreted as the maximum number of individuals
of a species that could be supported by a given habitat under various
conditions of stress. The general goal implied is to maximize the
productivity of the system, e. g., to maximize the number of cattle
marketed from a given range, or to maximize the number of board
feet of lumber harvested from a given forest, or to maximize the
number of user-days of recreation at a particular site, subject to the
constraint of nonimpairment or nondegradation of the supporting
environmental system.
16
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Population
(3)
carrying
capacity
Time
Figure 2. Population carrying capacity.
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Focusing on the nonimpairment or nondegradation aspect of carrying
capacity, Deitchman (1972) postulates an interaction model, following
the general concept of the Volterra model, which involves four classes
of "things" that enter into the pollution control problem. The four
categories are resources, R. (including pollution sinks); manufactured
goods, M. (interpreted broadly); populations, N. , associated with
these goods through production or associated services; and resulting
wastes, W. . The proposed set of equations takes the form:
dR.
-r-1
dt
= k R. + (3
~
n
i =
"
R
n
s b
R.M.
n
R.N.
dM.
£
__=k
, n
«. 1
K/rM. + B " S a
M. i M. . , M
1 T 1 — 1
' M"K"+%V,T
11 X J Mi
^ S
Mi =
M.W.
n n
S b.. M.M. + 6A/r S c M.N.
M . i j M M i j
-i ij i j-i ij
dN.
— —
dt
, n , n n
N. +p" S aT N.R.+ r" S b.T N.M.+6" S c.T N.N.
i PN£ j=1 Ny i J N. j=1 N.. i j Nj j=1 N.. ! j
Ni =
N.W.
dWi
_ i
At
dt
-in _! n
W+S 2 a WR + V S b
W i PW W i i "W
W., i w£ =1 wy i j w. =1
WM +6 S c WN
i i W W i i
j w. =1 w i j
.
18
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Deitchman (1972) notes that in representing the pollution control system
in open-loop form it is not necessary to assume rules of behavior about
society or the economy. However, he states, "solution of these non-
linear equations in closed mathematical form would, of course, be
difficult; and for numerical solutions the coefficients must be quantified
based on actual or projected data about the elements of the pollution
control problem. " However, Deitchman suggests the equations might
be simplified and, from theoretical explorations (similar to those
described by Goel, Maitra, and Montroll, 1971) and parametric numeri-
cal analysis, be used to explore stability and other characteristics of
the system.
Ecosystem Properties and Carrying Capjacity
If the concept of carrying capacity is to be useful it must enable the
environmental manager to assess and evaluate the impacts of various
proposals on regional environmental quality. To do this requires
insight and understanding of the behavior and interaction of ecological
and urban systems and of the ways in which the "health" of regional
support systems can be measured and the time-dependent changes
therein monitored. Whereas carrying capacity has primarily been
framed in terms of the ecosystem, operationalizing it as a basis for
environmental management will require finding corresponding processes
that will be applicable to the human environment.
The search for parallel bases for studying urban and ecological systems
is evidenced by the rising interest in "urban ecology. " Holling and
Orlans (1971) note that urban and ecological systems share four
common characteristics:
19
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1. A historical property since both respond to present and past
events.
2. A spatial property, since they respond to events at several
different points in space.
3. A systems property, since both encompass many different
component activities with complex feedbacks and interactions.
4. A structural property, since they both exhibit characteristics
of lags, thresholds and limits.
The second, and third, and particularly the fourth property, all intimate
the potential usefulness of carrying capacity in the urban setting, and
Rolling and Goldberg (1971) indicate that a combination of these four
characteristics produces distinctive system behaviors in terms of two
properties, stability and resilience.
In describing stability, the example of temperature regulation of warm
blooded animals used by Hardin (1963) and Rolling and Goldberg (1971):
In man the temperature is close to 98. 6°F. If through
sickness or through dramatic change in external temperature,
the body temperature begins to rise or fall, then negative
feedback processes bring the temperature back to the equili-
brium level. But we note this regulation occurs only within
limits. If the body temperature is forced too high--above
106°F., the excessive heat input defeats the regulation. The
higher temperature increases metabolism which produces
more heat, which produces higher temperature, and so on.
The result is death.
Thus, stability in ecological and urban systems recognizes the exis-
tence of damping forces that tend to move the system towards an
equilibrium state. However, given the dynamic nature of ecological
and human systems, this equilibrium is likely to change continuously
20
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with time, and hence the importance of stability may be more in
reference to the structure of the system itself. Also, as was seen in
the temperature example, stability is not identified with just a single
equilibrium point, but with the range within which the temperature can
be regulated. This fact gives rise to a second important property of
the ecosystem.
The concept of resilience is associated with the limits or domain of
stability of the system. The representation in Figure 3 from Holling
and Goldberg (1971) provides a graphical picture of resilience and its
relation to stability. Holling (1969) and Holling and Goldberg (1971)
have offered resilience as a potential measure of the integrity of com-
plex systems. A generalized definition of resilience might be stated
as follows:
Given an n-dimensional state space analysis of a system,
the system is said to be stable within a domain contained in
that sta.te space if it always tends toward an equilibrium point
or an equilibrium oscillation within that domain. Resilience
is a measure of the size of the domain of stability, the forces
acting on the system within that domain, and the location of
the system with respect to the boundary of the domain.
Transient shifts may force the system outside the domain of stability
and cause radical changes to occur. The types of transients or forces
have been classified in terms of pollution processes by Koenig and
Tummala (1972). Using their illustration in Figure 4, they describe
these as:
1. Nonpollution Levels: If the exchange rates are such that the
ecological state will remain within a given quality region S ,
q
for example, they are said to be of a nonpolluting level. The
21
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Upper
Boundary
of
Stability
Q
Stable
Equili-
brium
Lower
Boundary
of
Stability
Domain of
Stability =
Resilience
Time
Figure 3. An example of a system with a stable equilibrium in
which stability is possible within distinct boundaries.
TO m
•-J
-------
lake or stream is said to have a corresponding material
processing capacity.
2. Reversible Pollution; If the input rate is such that the
ecological state may eventually move outside the quality
regions S , for example, but will eventually return to
quality region S once the stimulus is removed, or is
"neutralizable" by a counter stimulus, they are said to be
at a reversible pollution level. The clean up of Lake
Washington is well known.
3. Nonreversible Pollution: If the input rates are such that the
ecological states may eventually move outside equality
regions S , for example, to the extent that the state can-
^ i
not be returned to S by reducing the stimuli, they are
said to be at a nonreversible pollution level.
A crucial point is that the size and configuration of the stability domain
can be altered as a result of perturbations of the system. With each
successive perturbation, the system becomes less capable of absorbing
additional disturbances (i. e., the size of the stability domain is
decreased). In effect, then, resilience is a measure of the ability of
the system to withstand shocks or perturbations. While incremental
shocks or changes can be absorbed, the accumulative effect of small
perturbations might reduce overall systems resilience. While the
current state of the art precludes any formal mathematical treatment
of the resilience concept, its use as a factor in defining carrying
capacity shifts attention away from "optimum, " "maximum, " or
"equilibrium" descriptions of systems behavior and toward descriptions
of systems behavior near the boundary between stability and instability
23
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where environmental degradation is likely to begin. Holling and Orlans
(1971) stress the need to understand "the complex nature of tradeoffs
and limitations and options and resilience that characterize systems
operating close to the carrying capacity of the environment. "
While it is not yet possible to quantify the resilience of a complex
system, the concept of systems resilience points out the importance of
considering such things as boundaries, thresholds, tolerances, and
limits in effective management of complex systems. Even though we
lack the mathematical sophistication to directly apply the concept of
systems resilience in analyzing the effects of various types of stress
on the system, any definition of carrying capacity should incorporate
such boundary-oriented concerns as limiting factors (environmental
factors which physically or behaviorally limit growth, reproduction,
or resource use of an individual, community, or activity) and trigger
factors (factors which at a certain threshold set off a chain of events
in an ecological or urban environmental system).
These basic ecosystem properties highlight the fact that the task of
defining and determining carrying capacity must incorporate an under-
standing and analysis of system boundaries and processes. This
realization is summarized by Holling and Goldberg (1971) as follows:
It is this boundary oriented view of stability emerging
from ecology that can serve as a conceptual framework for
man1 s intervention into ecological systems. Such a frame-
work changes the emphasis from maximizing the probability
of success to minimizing the chance of disaster. It shifts
the concentration from the forces that lead to convergence
on equilibrium, to the forces that lead to divergence from a
boundary. It shifts out interest from increased efficiency to
the need for resilience. Most important, it focuses attention
24
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on causes, not symptoms. There is now, for example, grow-
ing concern for pollution, but the causes are not just the
explosion of population and consumption, but also the implosion
of the boundaries of stability.
PROBLEMS IN DEFINING CARRYING
CAPACITY DIMENSIONS
Description and analysis of environmental carrying capacity, as the
foregoing discussions and examples indicate, must be performed within
properly identified and dimensioned domains. The domains of key
concern are spatial and temporal. The problems arise in that dimen-
sions and boundaries of these domains in the human environments do
not neatly map onto or correspond with the dimensions in the natural
environments. This gives rise to the additional problem of making
social and environmental trade offs.
The Spatial Domain
Simple one-dimensional point estimates of carrying capacity are neither
realistic nor practical. All of the following examples illustrate that a
broad spatial representation of capacity must be taken into consider-
ation: Levels of population and employment, traffic flows of all types
through the region, weather conditions, actual and potential socio-
economic structure, technology (particularly in regard to the residual
component of both production and consumption activity), transport
systems, the price system including prices on goods with negative
utility such as residuals, and the preferences of regional residents for
environmental quality, economic growth, etc. In terms of the spatial
25
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domain of natural systems Cooper and Vlasin identify the problem as
one of distribution of pollutants to prevent overloading (a boundary
condition problem) which, destroys the structural integrity of the
natural-biological community. They note that
Natural inorganics like heavy metals, synthetic compounds
that are toxic (PCB1 s, nondegradable pesticides, etc. ) and
radioactive materials are often assimilated but result in
organic products that have toxic characteristics to other
biological organisms. The accumulation of these materials
in the ecological system is a major threat to the aesthetic
and human health characteristics of our environment. Distri-
bution (dilution in space) cannot be considered a feasible
solution to the waste disposal problems with these materials.
Hence, the definition must allow for natural-human resource trade offs
in the spatial domain of at least two types: (1) For a given set of
environmental standards there are trade offs among activities such as
reduced employment--greater population, fewer people--greater
vehicular traffic, etc., and (2) trade offs between standards or goals
and economic activity such as reduced air quality standards and a
wider range of fuel use, or between the rustic rural life characterized
by low average income and the faster paced, congested urban situation
with significantly higher incomes.
For a given set of standards, the price system will have an effect on
carrying capacity. Two of the most pressing urban problems are
congestion on the city' s transport system especially at peak-use hours
and air pollution. Both of these represent'a failure of the market to
efficiently allocate the scarce resources involved, namely road space
and fresh air. In both cases, the effective marginal cost of the
resource to the individual is zero, and, thus, it is not surprising
26
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that quantity demanded for expressways and for clean air exceeds the
quantity supplied at that price. Through user charges for expressways
and charges for discharge of pollutants into the atmosphere, the scarce
resources could be more efficiently allocated. Highway toll charges
that vary with the level of use would encourage the use of car pools or
public transit, with the result of reducing the number of vehicles and
increasing the average speed of all vehicles. Effluent charges would
encourage the adoption of nonpolluting technology or investment in
pollution control devices. The revenues from both types of changes
could be used for social investment in highways, pollution control, or
whatever else was deemed desirable, according to the preferences (i.e.,
taste for pollution) of the region1 s residents. As these tastes change,
carrying capacity of the region will change. If people find that a
cleaner environment is preferred to more income, they can vote or
otherwise indicate this preference; and to the extent policy makers are
sensitive to such pressure, rules will be changed. The identification
of the optimal level of pollution (equivalently, the optimal level of
resource "purity") stands out as one of society1 s most pressing prob-
lems and is also one that seems to defy efforts to measure quantitatively.
The Temporal Domain
Carrying capacity must also be considered in a dynamic or temporal
context. Cooper and Vlasin find that expectations concerning time
required for system response or achievement of goals is a fundamental
difference between the natural and human environments. The natural
environment works on an evolutionary time scale where "the criteria
of success require survivorship for many generations." Thus,
27
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short-term decisions, such as those of the human environment which
are usually oriented toward present generations, have a greater likeli-
hood of being fatal.
In the human environment, the temporal perspective is also an impor-
tant aspect of control and survival. Economic mechanisms stimulate
technological advances and related investment, probably in response to
the set of prices, and may lead to increases in carrying capacity over
time. The development of internal combustion engines generating
lower emission levels per RPM will allow greater traffic volumes in
the region. Improved production processes will enable greater output
from given input quantities, and will, thus, facilitate greater output
without increased demand on the region' s stock of resources. Improved
technology in transportation (e.g., bigger and faster airplanes and
trucks, traffic control devices, more efficient terminal facilities) will
work toward increasing the average speed of movement of goods and
people and will tend to lower per unit costs. Cities having well devel-
oped expressway systems for automobiles, for example, tend to be
able to move traffic about and through the city at significantly higher
speeds than cities without such systems. Viewing the temporal domain
of socio-cultural institutions, Cooper and Vlasin point out that "urban
planners develop twenty-five year master plans. Economists develop
econometric models with eight to ten year projections. Politicians
respond at six, four or two year intervals depending upon their
election cycles. None of the control mechanisms currently existing
in the human sector, however, deal with evolutionary or ecological
time domains. "
28
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Environmental-Social Trade Offs
In summary, it seems clear that rather than defining carrying capacity
as a certain level of population or some other point criterion, it must
be defined in terms of a rather complicated function or set of functions
which would include a number of regional characteristics and economic
parameters, and would make explicit the possible trade offs that are
implicit in the definition. This requires a representation then of "the
set of social trade offs between the layman1 s concept of environmental
quality and the degree to which human society desires or needs to
utilize the production and assimilation capabilities of the natural
environment. " (Cooper and Vlasin).
CARRYING CAPACITY--A HUMAN
ORIENTED DEFINITION
To date, the concept of carrying capacity has mainly been used and
applied in terms of ecological systems. The notion of an upper bound
on population has been widely applied as a tool for the management of
natural communities (ecosystems). Generally, the upper bound on the
population density of a particular species has been set as the maximum
population density for that species which can be supported by a given
environment (habitat, ecosystem) without degradation. Many of the
difficult problems of environmental management arise, however, in
the urban-regional context. Since urban systems interface with natural
systems and since natural systems are a part of urban systems, the
concept of carrying capacities in this setting is in need of an enrich-
ment in definition and interpretation.
29
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When applied to human activities, the carrying capacity theme becomes
much more complex. In examining the critical interrelationships
between human and economic activity and the changes wrought upon
resources and the environment of a region and their capacity to
accommodate such change, it can be seen that the concepts associated
with the term "carrying capacity" must be greatly broadened to find
appropriate application in the realm of human activity. Rather than a
single fixed number being rigorously established as a "population
carrying capacity, " it suggests that we must be concerned with a
number of resource limits and environmental factors that may act as
constraints or damping forces in the dynamic interaction of population
growth, related socio-economic activity, the resource base, and the
environment as an assimilator of waste by-products. Attention, there-
fore, is directed toward viewing the regional environment as a support
system for numerous, interdependent, and frequently competing
activities and subsystems, where the determination of carrying capac-
ity rests upon desired human and environmental quality levels which
are circumscribed by a wide variety of political/institutional, physical/
biological, and social/cultural constraints.
From this and the previous discussion it should be clear that a human
oriented carrying capacity cannot be developed in a simple, single,
numerical measure. It is not only a multidimensional concept but it is
subject to constant change and modification particularly as technological
improvements are made and as rules change due to pressures from the
region1 s residents.
30
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A Normative Definition of Carrying Capacity
The basic elements involved in the definition of carrying capacity hinge
on the interrelation of resources, processes which convert those
resources to desired outputs, and waste products and residuals which
must be assimilated back into the resource base with future effects on
quantity and quality. This simplified picture of carrying capacity is
diagrammed in Figure 5.
Viewing Figure 5 as a closed system, carrying capacity may be seen
as the ability to produce desired outputs (goods and services) from a
limited resource base (inputs or resources) while at the same time
(2)
Natural Re-
sources and -
Environment
Residuals
Wastes
(1)
Activities
Process
outputs
-------
maintain desired quality levels in this resource base. For an open
system, the definition would further have to allow for import of both
resources and goods and services, and the export of production and
residuals. The basic diagram of Figure 5 yields four dimensions which
are relevant to the overall measurement of carrying capacity.
1. Resource-production relations: The capacity of available
resources to sustain rates of resource use in production.
2. Resource-residuals relations: The capacity of the environ-
mental media to assimilate wastes and residuals from
production and consumption at acceptable quality levels.
3. Infrastructure-congestion relations: The capacity of infra-
structure resources (distribution and delivery systems) to
handle the flow of goods and services and resources used in
production.
4. Production-societal relations: The capacity of both resources
and production outputs to provide acceptable quality-of-life
levels.
Working from these four relationships, then, human carrying capacity
is defined as follows: Carrying capacity is the level of human activity
(including population dynamics and economic activity) which a region
can sustain (including consideration of import and export of resources
and waste residuals) at acceptable "quality-of-life" levels in perpetuity.
32
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An Operational Definition of Carrying Capacity--The
Human and Natural Environmental Trade Offs
The high degree of interrelation among resources, environmental
media, and desired quantity and quality states for human and associated
socio-economic activity underscores the fact that trade offs must
inevitably be made among desired product!on-consumption levels,
resource uses, and a cleaner, healthier and more pleasant environ-
ment. From this perspective, carrying capacity must be interpreted
as a variable which is essentially socially determined within our under-
standing of economic, social, and environmental values and their
relative contribution in maintaining quality-of-life levels. This dual
perspective required in providing an operational meaning to the defini-
tion of carrying capacity is presented in the flow diagram of Figure 6.
The diagram illustrates that the working use of the carrying capacity
definition requires a series of adjustments to reconcile the capacity
limits related to quality levels of the natural environment and desired
levels of consumption of goods and services by society. For example,
some of the key issues in examining these trade offs in acceptable levels
of "carrying capacity" are:
1. What are the costs and benefits of developing (preserving)
a resource or relaxing (enforcing) an environmental standard?
(For example, reducing air or water quality standards in
the face of the fuel shortages in order to allow particular
resource developments.)
2. What are the ramifications of removing a capacity constraint
through new or improved technology, learning, or new
resource discovery?
33
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Goals for Growth
and Environmental
Quality
current
Future Desires
and Social
Carrying Capacity
newly identified
requirements
futur e
Inputs of
Future Resources
Discrepancies Between
Future Social and
Environmental Capacities
problems
Policy Alternatives for
Growth and Environ-
mental Management
Feasibility and Analysis
Cost-Benefit
Trade-offs of
Alternatives
Evaluation of Effective-
ness of Alternatives
Decisions on Human and
Environmental Carrying
Capacity Trade-offs
Future Resource
Capabilities and
Carrying Capacity
technology and
resources
implications for
policy objectives
Figure 6. Flow diagram for an operational definition of carrying
capacity.
34
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The adjustments between future desires or social capacities and
resource capabilities in operationalizing the normative definition of
carrying capacity are partly technical questions where analytical models
can usefully be applied and partly value questions where social and
political mechanisms are required. The integration of the two must be
accomplished within a carrying capacity-based planning and decision
making process. Such a process is formulated and described in
Chapter 5. The implications of these carrying capacity definitions
direct attention to important issues in managing urban-regional growth
in terms of efficiency of energy and material transfer, handling of
wastes and by-products, and capability of human and natural environ-
ments to support activities.
35
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SECTION IV
RESOURCE DESCRIPTION AND
CARRYING CAPACITY
RESOURCE CLASSIFICATION AND
CHARAC TERISTICS
Traditionally, resources have been viewed either as elements of the
natural environment or as inputs to economic production. In urban
areas, where much of the living environment is essentially man-made
and serves as a means of organizing man's activities, it appears that
our definition of resources and related environments is much too
narrow.
In extending the concept of resources in examining the capability of a
region to sustain existing and proposed activities, consideration must
be given to aspects of three resource systems--character and extent
of the natural resources, the infrastructure resources and functions of
urban areas, and the social-cultural resources of people and institu-
tions--which circumscribe the domains for carrying capacity in a
region. The relation of these systems to the capacities of natural and
human environments is diagrammed in Figure 7.
36
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Natural
Environment
Natural
Resources
(Physical/Biological)
Envir onmental
Capacities
Infrastructure- Transformation
Resources
(Physical/Economic)
Human
Environment
Socio-Cultural
Resources
(People/Institutions)
Figure 7. Environmental-resource relations.
These resource systems might be thought of as the basic building blocks
of a region, as illustrated in Figure 8, in which each part of the struc-
ture interrelates with the others in establishing carrying capacity.
In determining the resource base, quantity and quality are two resource
attributes that are inextricably connected so far as carrying capacity
for a particular activity or use is concerned (e. g. , volume of water of
quality for drinking, or for cooling; space and transport network capa-
bility for movement of vehicles, or institutional mechanisms for
preserving open space).
37
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Imports
Socio-Cultural Resources:
People and
Institutions
Infrastructure Resources/
and Transformation Activity
Natural Resource Base
Exports
Figure 8. Resource systems in regional structure.
From the perspective of carrying capacity, rather than assuming the
usual land, water, and air delineations, the description of natural and
human resources environments (see Perloff, 1968) might be elaborated
along the following lines:
Ambient resources:
Spatial resources:
Infrastructure and
distributive resources:
Ecological resources:
Socio - cultural
resources:
Air, water, open space, quiet and
noise zones, sunlight exposure
Underground space, available and
transitional surface space, airways
space
Transportation, water and water dis-
tribution, wastewater collection,
energy (electricity and gas) distribution,
c ommuni c ati on s
Green plants, nongreen plants, animals
Educational and cultural facilities,
health services, security services (fire,
police), recreation services, housing
stocks
38
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Economic resources: Raw materials for production inputs,
capital, labor
Amenity resources: Seashores, scenic areas, contiguous
natural areas (mountains, deserts,
lakes), open space
Some attributes or characteristics of these classes or types of urban
resources which enter into an assessment of their capacity to support
a particular activity or changes in sets of activities are displayed in
Table 1.
Relative to these resource descriptions, the environmental planner and
manager must seek to understand such questions as: What are the
relevant resource components? How do they function? How do they
interact with and influence other components, or conversely, how are
they influenced by other components? What factors control levels of
environmental quality and how do proposed plans or actions affect those
factors? The classifications in Table 1 provide insight into such
questions about the function and structure of urban environmental
resources and their interactions with one another, and are central to
specifying the domains of environmental carrying capacities for urban
regions.
Renewability
The quantity and quality of a resource is closely related to its charac-
teristics of renewability or nonrenewability. Stock resources, such as
mineral deposits, fossil fuels, and available land, are essentially fixed
in quantity and in that sense nonrenewable. The capacity of such
39
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Table 1. CONSIDERATIONS IN RESOURCE CLASSIFICATION
^v. Class
ResourceX^
Ambient
Spatial
Transforma-
tion Distributive
Ecological
Socio- Cultural
Economic
Amenity
Renewability
Stock Flow
Nonre- Renew -
newable able
X
X
X
X
X
X X
X
Mobility
i* u-i •^tn~
Mobile ...
mobile
X
X
X X
X
X X
X X
X
System
' Infra -
... ^ , Struc- .Social
Natural . _ ,. .
ture Cultural
X
X
X
X
X X
XXX
X X
Ownership
Private ^^c Control
Control Re_ Na_
iiocal .
gional tional
XXX
X XXX
XXX
X XXX
X X
X
X XX
-------
resources for supporting urban systems, therefore, depends on rates
of use or exploitation, the possibilities for salvage and recycling, and
the development of substitutes. Naturally renewed resources (natural
vegetational and animal growth) and flow resources (solar radiation
and natural cycles for water and other elements) have renewable charac-
teristics in which process rates determine the quantity and quality
available in a given time period. Capacity of renewable resources
depends on the care and efficiency of man's intervention in the use of
the resource without upsetting or destroying the natural processes
which assure the resource availability.
Mobility
Mobility, as it affects the spatial distribution of resources, is an
important part of identifying which resources are part of the urban
region itself. Drawing boundaries around the urban region in order to
geographically circumscribe the resources which contribute to its
carrying capacity may be a difficult and sometimes arbitrary task.
Electrical energy, water, and fossil fuels are resources which are
often situated large distances from actual centers of urban activity.
Should they be considered as external or imported resources? This
question raises the broader issues of environmental quality relations
between areas of resource extraction or production and areas of resource
use. The carrying capacity concept recognizes that the interface
between the city and nonurban areas has become more explicit, particu-
larly in the couplings established through resource development,
energy production and transfer, pollution outputs, and deterioration of
contiguous agricultural and recreation lands due to urban sprawl.
41
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Systems
Description of resources systems provide a basic structure for deter-
mining how growth, as measured against resource capacities, will
affect regional environmental quality. Basic components of resource
systems are briefly noted in the following.
Natural Resources System--
Although a logical starting point, it is difficult to define carrying
capacity completely in terms of a finite resource base, since a resource
is important only as it is transformed into an array of services. It
does not represent a single service or output in most cases. The
outputs and services of concern in terms of system carrying capacity
are (1) the production of goods and services at levels consistent with
society's desired quality of life, and (Z) the capacity to assimilate
wastes and residuals into receiving media at levels which meet acceptable
standards of environmental quality. The impact on natural resources
of providing these services is diagrammed in Figure 9. Of particular
interest in the flow chart is the natural resource base as a "sink, "
which is usually a common pool resource. In terms of residual assimi-
lative capacities, many regions are apparently operating at levels far
beyond what could be maintained within a strictly closed regional
system. The unsolicited import and free export of harmful residuals
from production and consumption are of particular concern in analyzing
carrying capacity since they have not responded in a satisfactory manner
to private incentives as expressed in the market. Also, the problem
of trade offs is clear in examining the outputs, since the consumption
42
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OO
Resource
Base
Extraction
Tr ansf ormation
Resource
Refinement
Manufacture
Sink (air,
water,
land)
Regional
Impact
Bulk Energy
Conversion
Production
of Goods
& Services
Economic
Growth
Use and
Consumption
Social
Demands
Figure 9. Flow of resource from and to the natural system.
-------
of goods and services which contributes to quality of life are the same
activities which generate the wastes which reduce quality-of-life levels.
The proper balance and trade offs between these in accommodating
growth is one of the central issues in carrying capacity.
In examining natural system structure, it appears that there will
usually be a hierarchy of limiting factors for any region, although only
a few resources will actually be the effective constraints in limiting
growth and development at any one point in time. These factors may
be on the resource input side, the waste assimilation side, or else a
small number of factors will act in combination to present limits to the
region. These factors determine natural resource system limits for
the region, and affect the distribution of population and activity across
the region.
Infrastructure Resources System--
Superimposed upon the mosaic of natural (physical and ecological)
resources of a region is the domain of urban infrastructure as a resource
system. The composite of urban activities, both public and private,
such as education, health, industry, commerce, recreation, agriculture,
and personal services contribute to a set of regional outputs of physical
products or elements which contribute to quality of life. These activities
are linked and supported by the infrastructure and resource distribution
systems of the region.
The existing regional infrastructure represents the carrying capacity,
at least in the short run, of a region's capital stock to provide or
44
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distribute needed services, such as transportation, energy, water,
and waste disposal. Hence, the rates of flow or service delivery are
limited by the capacity of the system. Some of the elements of regional
infrastructure which have important interrelations with the carrying
capacity of the region are noted in Table 2.
Table 2. DESCRIPTIONS OF REGIONAL INFRASTRUCTURE
Type
Service/ Output
Descriptive
Dimensions
Public Utilities
Public Services
Land Utilization
Resource Transfor-
mation and produc-
tion
R esiduals Mana ge -
ment
Water supply, energy
distribution (electricity,
gas), communications
Schools, health care,
recreation, cultural
and entertainment
Housing, transporta-
tion
Industrial production,
commercial and mar-
keting
Sewer systems, solid
waste disposal, air
emissions controls
Sources and location
service area, size and
scale, peak loads
Location, population
served
Quantity and quality of
housing stock, rates of
deterioration, peak loads
existing capacity, net-
work and service char-
acteristics
Capital and investment
depreciation rates
Air, land, and water
quality standards,
waste loading, media
characteristics
45
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The current capability of the infrastructure and the resources they
distribute to sustain activity is a key aspect of the "carrying capacity"
of an urban region, and, as such, represents short and medium run
constraints on regional quality growth.
Social-Cultural Resource System--
People and institutions represent the third important resource capacity
system, which operates to govern the human environment. Institutional
and individual values as reflected in present or desired life styles of
the residents of regions should tell importantly in determining quality
aspects of regional growth. Social scientists have argued that social
and economic development is best measured by observing the latitude
and distribution of choices available to a given population. To prespecify
capacity limits on selected system outputs without consideration of
social-cultural capacities can narrow this range of choices or possibly
expand the range for particular subsets of the population at the expense
of others.
Ownership; Economic and Social Costs
The classical concept of common property or "free good" resources has
little validity in terms of carrying capacity for sustaining regional
activity and growth. In the reckoning of social accounts, there is now
a high cost associated with maintaining the quality of ambient resources--
air, water, etc. The industrial firm dumping wastes directly to a
stream, airplane flightpaths over residential areas, the individual
automobile adding to congestion and air pollution, the building that
46
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blocks out the sun are all examples of individual actions contributing to
a deterioration in environmental quality for the whole of society (Perloff,
1968). What levels of activity in use of common resources should or
can be permitted is certainly a question in the domain of the carrying
capacity concept.
RESOURCE CAPACITY CONSIDERATION
Carrying capacity, as viewed from the standpoint of resource impacts,
has two distinguishable but related meanings, both of which seem to be
important for management purposes. These are: (1) The capacity of
the environment to supply resources for certain activities (supportive
capacity) and (2) the capacity of the environment to act as a sink for
wastes produced from certain activities (assimilative capacity). The
"sustained yield" concept pertains to both meanings, but has been used
most often in relation to the former; "systems integrity" concepts
(e. g. , resilience, stability) also apply to both meanings. The general
relationship of the two meanings is illustrated by the diagram in
Figure 10.
Taking into account the interactions with other activities, the diagram
appears as in Figure 11.
The following provide some simple integrating examples of supportive
and assimilative capacities of the two broad classes of environment.
(1) Natural environment Capacity of an aquifer (or other
Supportive capacity water source) to support water
needs of a small community
47
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Capacity of the
environment to
support (sustain)
activities
[supportive capacity]
res ource inputs
•vjb
' XT**
'&
f* 4*
Capacity of the
environment to
assimilate
activities (wastes,
etc.)
[assimilative capacity]
Figure 10. Relation of supportive and assimilative capacities.
Supportive capacity
for activity.
Other activities ^_
activity.
\/
Assimilative capacity
for activity.
Figure 11. Activity interactions and carrying capacity.
48
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(2) Natural environment
Assimilative capacity
(3) Human environment
Supportive capacity
(4) Human environment
Assimilative capacity
(5)
(6)
.Example of interactive
effects between support-
ive and assimilative
carrying capacity
(human environment)
Examples of interactive
effect between support-
ive and assimilative
carrying capacity (nat-
ural environment)
Capacity of a lake to assimilate
municipal/industrial/agricultural
wastes
Capacity of a community tax base to
support schools and other public
services in a suburbanizing area
Capacity of recreationist to assi-
milate crowding and congestion (and
other encroachments) at recreational
sites
Inability of society
•^
to support pollution
control measures
Water in reservoir
(deteriorating quality)
Increasing
pollution
Increasing con-
cern about
•seriousness
of pollution
problems
Water -based
recreation
•
.
Inability to
absorb/accom-
modate/with-
stand pollution
Systems Capacities
Approaching the description of environmental carrying capacity at the
resource level (natural, infrastructure, and socio-cultural) yields the
following interpretation:
Resource Capacity--
Resource capacity is basically a biological and resource flow definition.
Capacity is examined in terms of the levels or input rates for an activity
49
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that can be withstood by the biota or the resource flow systems and still
return to an unimpaired state. Essentially this suggests a nonimpair-
ment criterion for establishing levels of use which can be sustained for
an indefinite period of time without altering or degrading the resource.
The underlying objective, then, is achieving a maximum sustained yield
for a given activity. The important factors in analyzing resource
capacity are the ability of the resource to produce the kinds of services
required, and the ability of the biota or flow system to recover after
peak use (for example, the ability of air and water to assimilate certain
pollution waste loads over a period of time without permanent deteriora-
tion of ambient quality conditions).
System Constraint Capacities--
System constraint capacities are concerned more with the physical
limits of resources or of resource processing and use systems.
Physical resource limits would be considered in terms of nonrenewable
stocks or resources such as mineral deposits, fossil fuels, and available
land (in the short and medium run), and the rates at which such resources
are being developed and used. For the resource processing infrastruc-
ture, the capacity for use of both nonrenewable and flow resources may
also be limited by the capability of the present system to transform and
utilize them. For example, a certain forest area might be producing a
net annual increase in timber which is greater than can be harvested on
a sustained yield basis because it is inaccessible from the current
transportation system. The objective indicated by this definition is
efficiency in resource use and in the management of resource processing
systems.
50
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Social/Psychological Capacity--
The determination of social/psychological carrying capacity depends
upon a wide variety of political/institutional, physical/biological, and
social/cultural constraints. Social/psychological carrying capacity is
related to the overall levels of satisfaction experienced by users or
other affected individuals resulting from resource management practices.
Social capacity is stated in terms of maximum number of use-units
(e. g. , people, vehicles, etc. ) that can utilize available resources during
a specified period of time for one or several activities while providing
a satisfactory experience for the users. One operationalization of this
goal in determining a "satisfactory experience" might be to maximize
the total user satisfaction. Before determinations can be made about
levels of "satisfactory experience," the kinds of experience the resource
is expected to provide must be established. A particular resource or
group of resources may be capable of providing for several different
types of activities. Some of these activities will compete for the
resources, while others may be compatible. Almost inevitably, this
will require a management decision as to which resource use or combina-
tions of uses will be pursued. An example would be whether a particular
tract of land should be zoned and managed as open space or used for
various kinds of residential and commercial development. Deriving a
set of management objectives must take into consideration the feasibility
of the objective in terms of resource capacity and system constraint
capacities.
The aspect of "satisfactory experience" or user satisfaction is a
function of individual attitudes with respect to the management objectives
in question. In this context the question becomes "How many people can
51
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be handled in an activity at one time before the quality of the experience
is lost? " or stated another way, "What number of people maximizes
the total satisfaction in the use of the resource for a particular
experience? "
SUMMARY
A general and broad picture of resource description in relation to
carrying capacity with regional structure and forces of change .and
growth is presented in Figure 12. The figure illustrates the highly
interrelated nature of resources described in this chapter in deter-
mining and measuring regional carrying capacities.
52
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URBAN/ REGIONAL SYSTEMS:
Structure, Function,
and Interaction
f Ambient •
URBAN/REGIONAL
RESOURCES
Spatial-
Infrastructure
and
Distributive
Ecological 4
Socio - Cultural!
Economic—-—
^•Amenity-
Bearing
Capacity
Constraint^
Capacity
Socio-psychological
Capacity •
Limiting
Factors
Trigger
Factors
Human and
Natural
Environmental
Quality
t
PROPOSED
ACTION
CHANGES IN RESOURCE
USE AND ALLOCATION
•IMPACT
•PERFORMANCE —'
Figure 12. Overview of resource-carrying capacity relationships.
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SECTION V
REGIONAL STRUCTURE AND CARRYING CAPACITY
INTRODUCTION
The potential of a region to support a human population appears to be
significantly related to its structure. Regional structure, in turn,
can vary widely in its temporal and spatial dimensions because of
differences in natural and man-affected capabilities for production,
consumption, and assimilation. The production and assimilative po-
tential of natural environments tend to be highly responsive to energy
input (solar) and the availability of moisture such as in humid, semi-
tropical regions. Their potential for sustaining human activities is
considerably less in cooler-drier regions where human environments
tend to locate and grow. Assessment of regional structure as it may
influence carrying capacity includes a knowledge of the magnitude and
diversity of natural and human environments and the distribution of
activities within these environments over time and space. In the sec-
tions which follow, regional structure of the human environment will
be examined in terms of alternative spatial contexts and in terms of
the composition and growth of activities in response to both exogenous
and internal factors.
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SPATIAL CONTEXT FOR EXAMINING
REGIONAL CARRYING CAPACITY
The selection of a spatial context for defining carrying capacity may
be fully as important a consideration as the selection of variables
(inputs, outputs) which comprise it. Virtually all definitions of regions
fall within three main categories. These categories or approaches to
regional delineation are defined in terms of homogeneity, nodality, and
programming or policy.
Delimitation based on homogeneity stresses the similarity of one or
some combination of physical, biological, social, economic, and other
features which characterize a region. For example, regions could be
delineated on the basis of physical characteristics by classifying them
in accordance with dominant physiographic features, resources, and
climate. Social characteristics might include such things as attitudes,
race, and religion. Important in the context of carrying capacity are
the economic features. These might include regions with similar socio-
economic structures, homogeneous patterns of consumption, and/or
production. Product specialization and income levels serve as impor-
tant economic characteristics which are often used for defining regional
economic conditions.
Delimitation based on nodality emphasizes the dominance of the urban
center of a region. Focus is placed on the interdependence of different
activities within the region, rather than interregional activities or
relationships between homogeneous regions. Nodal regions are
55
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composed of heterogeneous units which, have close functional inter-
relationships. Such functional interconnections are typified by flows
of people, goods and services, communications, and traffic. These
flows do not occur randomly over a region, but rather the heaviest
flows tend to polarize towards and from a dominant central city or
nodal point.
Finally, regional definition based on a programming or policy focus
depends heavily on administrative coherence usually coincidental with
recognized political subdivisions and units of economic decision making.
Implementation of any overt regional policy or management concept
demands a capability for action. Responsibility for such action ordi-
narily rests with recognized governmental units which may or may not
be coincident with important components of carrying capacity. This
points to a possible trade off between the ideal policy region for which
carrying capacity is defined and the political jurisdiction under which
management may be feasible. If carrying capacity is defined indis-
criminately without regard to functional linkages between separate
spatial units, then information derived from it may be of very little
value because it cannot be implemented.
Regions defined on the basis of nodality and on the basis of policy and
programming are merely utilizing special cases of the homogeneity
approach. A program or policy region is essentially homogeneous in
being entirely under the jurisdiction of a few special governmental
or administrative agencies. Nodal regions, on the other hand, are
homogeneous in that they combine areas dependent on a specific central
city in some trade or functional sense. Ultimately, homogeneity with
56
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respect to statistical compilations and in terms of policies or programs
being applied may be the operational determinants of regional boundaries.
Regions defined on the basis of combining units with uniformly homo-
geneous characteristics should still exhibit a polarization of flows
between contained central cities or nodes. Whether the analyst directs
his attention to the homogeneous features of the region or to its nodal
characteristics depends primarily upon the nature of his inquiry. If
prime concern is directed to the planning problem of a single region,
such as definition and implementation of carrying capacity, it will be
necessary to concentrate on the polarization aspects and the inter-
dependence between separate subregional units. In contrast, if interest
is directed to the interregional relation of a particular areal unit, such
as the transference of business cycles from one region to another,
uniformity in their definition may be most appropriate.
Thus, it becomes obvious that the choice of an ideal region is con-
strained by the purposes for the delimitation of sets of regional
boundaries and by the overall structure and degree of integration of
regional systems. Further, the concept of "ideal" region can be
expected to change in relation to the elements of carrying capacity
which are the focus of policy. For example, the boundaries for
ecological spaces such as air sheds, hydrologic basins, aquifers and
ecological land areas seldom coincide with the boundaries of any single
decision-making unit, whether public or private. Under these circum-
stances aggregation across separately identified units of government
to approximate an integrated ecologic-socio-economic region may be
required in order to internalize the full implications (gains and losses)
associated with a policy decision.
57
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A suitable socio-economic building block which could be used for this
purpose is the functional economic area (FEA). Such areas are use-
fully viewed from the perspective of a single region to the interrelation-
ships within a broader metropolitan or national setting. Basically
these are employment demand regions which act as reasonably inde-
pendent units within a more complex spatial economic organization.
A basis for defining these "ideal" economic regions derives from a
recognition of the following: 1) Essential services and a major portion
of employment are provided by a central city or nodal center. 2) The
time cost of distance between central city and residence in the sur-
rounding area defines the outer perimeter of an areal unit. 3) Scale
economies in providing essential services determine viability of the
centers. The minimum number of persons living within the region
must be large enough to capture these economies. Regions so defined
are homogeneous in the extent to which their internal organization of
residentiary activities are essentially similar. At the same time,
they may be strikingly heterogeneous in terms of basic activities,
political organization, and resource base.
Most early applications of the FEA-delineation were limited to pre-
dominantly rural areas. However^ it seems not to be restricted to
that particular domain because the internal structure of an FEA is
essentially the same, whether in an urban or a rural setting. Large
metropolitan areas and surrounding hinterlands are merely FEA's
arranged in clusters of varying density. Thus it appears that carrying
capacity derived questions which transcend conventional political
boundaries could be examined within the context of an integrated region
without losing accountability at a functional or local level. However,
58
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such aggregations merely facilitate analysis and decision making at
an appropriate level and provide no assurance that "integrated" deci-
sions will follow mainly because of the impracticality and nonexistence
of formal regional governments.
REGIONAL ECONOMICS AND
CARRYING CAPACITY
Economic Composition of a Region
The economic structure of the region, essentially the composition of
employment and/or output from the various industrial sectors, will
influence and be influenced by any administratively set carrying capa-
cities. If environmental standards for air and water quality are fixed,
then regional activity in one or several heavy polluting industries will
involve significantly less total employment and, of course, population
within the framework of those established capacities than would be
the case if activity was concentrated in the relatively pollution-free
sectors. Clearly, from the production side it would take many times
the pollution generated by one steel mill or copper smelter. However,
things might be different on the consumption side. The pollution
generated by one banker's consumption habits would probably approxi-
mate or exceed that of one steel worker.
The spatial structure of the region's economy will also influence
carrying capacity and will be significantly influenced by the transpor-
tation network. If employment centers are scattered about the region
rather than being concentrated in, say, the central business district,
59
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congestion would tend to be reduced on the regional highway system
and residuals from both production and consumption (i. e., automobiles)
would be more generally diffused in the region's atmosphere and there-
fore more likely to be dissipated. Furthermore, to the extent that
workers sought residential locations near their place of employment,
the scattered employment center construct would result in less miles
driven (at least in commuting to work), less energy consumed, and
lower levels of residuals discharged.
Conversely, such a dispersed spatial structure is antithetical develop-
ment of mass transit systems that are generally more efficient than
automobiles in terms of fuel consumed and pollutants discharged per
passenger mile. Only when economic activity and commuting flows
are concentrated in one or two places can mass transit systems gener-
ate sufficient volume to be profitable, and even cities having this spatial
concentration have found it exceedingly difficult to keep their transit
systems operating without subsidies. In any event, capacity definitions
must include a measure or index of the degree of dispersal or concen-
tration of the region's economic activities.
The size of the region as measured by population and employment
will also influence economic structure. Virtually all market-oriented
activities have minimum or threshold population levels that must be
achieved before they can be profitably engaged in. For example, one
does not usually find a department store in a community of 500 resi-
dents, but one or two gasoline service stations are usually in evidence.
Efficient production of many goods requires a plant size above some
minimum level, and must only locate in an area where there exists
60
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sufficient labor to staff and operate it. The city of 500 mentioned
before is unlikely to be the site of a steel mill. Likewise, transporta-
tion system development will also be a function of size. Commercial
airline or railroad service is not generally offered to cities in the
absence of subsidies. Therefore, for smaller places which are un-
likely to become bigger places for either economic reasons or rules
regarding maximum size (or carrying capacity) certain economic
structures are unlikely to develop, and need not be given much analy-
tical consideration.
Role of Location
It is clear that the rate of employment and population growth, as well
as measures of welfare such as per capita income, should be signifi-
cantly influenced by the region's spatial location relative to the
metropolitan areas of the country and the existing transportation net-
work, especially the interstate highway system. In like manner,
carrying capacity is also dependent on the same locational attributes.
This Is due to the fact that the close proximity to a major metropolitan
area means that the residents in a region can use the services offered
by both private and public sectors of that metropolis for many of their
demands; the capacity for delivery of these services need not be
developed in the smaller region.
An empirical study of the effect of spatial location (see Lewis, 1973)
provides evidence that regions in close proximity to metropolitan
areas or to the transport systems linking those areas tend to experience
higher rates of growth in population, employment, and income as well
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as having significantly higher income levels. The implications are
clear. The development of transportation systems, effectively making
a region closer to a given metropolitan area in terms of economic
distance, will have growth impacts on that region. The present economic
size of the area in relation to its carrying capacity should be evaluated
in planning for and evaluating the impacts of new transportation invest-
ment.
Interregional Linkages
Focusing on growth in one or a set of regions in a larger, open economy
introduces several new dimensions that tend to be omitted in nation-
level regional description. Interregional flows of goods, services,
capital and residuals tend to be of greater relative importance than do
similar flows among nations. Depending on the nature of area de-
lineation, regions often are highly specialized in the production of
particular commodities or services. Therefore, a large proportion
of domestic output is exported, and, similarly, a large part of domes-
tic consumption and production requirements must be imported.
Depending on the regions1 saving habits and capital requirements,
there will also tend to be substantial interregional capital flows. Hence,
the implications for carrying capacity in the absence of import and ex-
port quickly emerge. Regional carrying capacities will tend to be very
small in relation to larger more diversified areas because of regional
specialization in production. Thus, carrying capacity of a region is
inversely related to the extent of its specialization in production while
for a multiplicity of regions it may be positively related to a variety! of
regional specializations.
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Movements of people among regions present an even more important
and more interesting problem. Less than capacity use of human re-
sources has stronger political and economic implications than does
unemployment of nonhuman resources. Unfortunately, labor tends to
be less mobile than capital, and areas of high unemployment, although
typically characterized by out migration, tend to remain such over
periods as long as several generations. Economic theory would suggest
that differentials in wage and unemployment rates (together with some-
thing of an expected income concept) would lead to equilibrating move-
ments of people from low-wage, high-unemployment rate regions.
Such movement is generally observed but, at least in recent history,
has not succeeded in the elimination of these differentials. There are
several possible explanations for this:
1. Individuals may prefer a lower expected income in the home
region to the uncertainty, discomforts, and cost of moving
to the "advanced area. " Essentially, this is an assertion
that people are "utility" rather than income maximizers and
risk averters rather than risk seekers.
2. The possible concentration of technical progress and scale
economics in growing regions may result in the marginal
product functions of both labor and capital increasing more
than enough to offset increases in the factor supply functions.
Such a situation would imply continuing wage and profit dif-
ferentials among the several regions. The speed of factor
movement in reaction to such differentials is critical in the
determination of relative factor prices among regions.
63
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Perhaps the point of greatest recent concern in examining interregional
linkages is the import and export of residuals and the extent to which
significant disassociations between gains and losses are introduced.
Both private and public decisions in a small region can easily ignore
the full extent of an "externality shed" which can be affected by these
decisions. Typically these residuals export problems occur along
river systems and air sheds where export of residuals is accomplished
at zero cost and their disbenefits are not internalized to the decision
process. To the extent that carrying capacities are defined for regions
in which residuals generated in production-consumption activities are
externalized to that region at no cost, they will be overstated. In
essence, such a region internalizes (appropriates) goods and services
for local consumption or for export to other regions while it socializes
an important portion of the costs of the residuals. Obviously, a full
accounting of import and export of residuals is critical to the deter-
mination of regional carrying capacity.
REGIONAL GROWTH AND
CARRYING CAPACITY
In ope rationalizing the concept of carrying capacity, it is important
to understand the process by which a region grows to or exceeds capa-
city. Furthermore, regional growth theory is conceptually capable of
being linked to models tiiat trace the total impact of economic growth
on virtually all aspects of the region, including the effects on demo-
graphic characteristics and environmental* conditions. Although a
regional growth model of general applicability and widespread accept-
ability has not yet been developed, most regional scientists agree
64
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that regional growth depends both on exogenous change in demand for
regional outputs and change in the supply and quality of the region's
stock of productive factors. In this section, an example of each type
of model will be outlined.
Demand Oriented Growth
The export-base model of regional growth is perhaps the most widely
used demand oriented model of regional growth. Although it has some
rather obvious shortcomings (see Lewis, 1972), it does take explicit
account of the importance of forces exogenous to internal growth.
Essentially, theory asserts that the region's basic activities (i.e. ,
those which involve the sale of goods and services to consumers whose
source of payment comes from extra-regional sources) form the basis
for the development of all other basic activities. Exogenous changes
in demand for output from a subset of the region's industries, arising
from outside the region, are the ultimate source of change in total
regional employment with population and labor force adjusting passively.
Generally, basic or export activity is concentrated in the manufacturing,
extractive, and agricultural sectors.
An example of an export-base type model can be developed in the
following way. Total regional employment (E) is identically equal to
the sum of employment in the basic (E ) and nonbasic (E ) sectors:
E = E, + E (1)
b n
Basic employment is assumed to be an exogenous variable in that it
65
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depends on those extra -regional forces that determine export demand,
= E° (2)
•while nonbasic employment is an increasing function of basic employ-
ment,
En ' al + BlEb
in which B > 0. Solving for total employment yields
E = a + (1 + B ) E (4)
in which the derivative of E with respect to EL, (1 + B ) is the total
employment multiplier associated with a change in basic employment.
B would be interpreted as a nonbasic employment multiplier.
The model is completed by adding an equation in which population (P)
in the region is a function of total employment
P = <^ + B2E (5)
Substituting Equation 4 into Equation 5 yields an equation for population
as a function of basic employment only
P = °2 + B2al + B2 (1 + Bl) Eb
66
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in which B (1 4- B } -would be considered a population -basic employ-
L* JL
ment multiplier.
Any change in the region's employment and population must stem from
changes in the one exogenous variable, E, . Strictly speaking, this is
not a growth model, although it is commonly referred to as such. In
a rather trivial sense, a growth model can be developed by assuming
basic employment to be increasing at a constant rate r,
in which t indexes time periods. Under this condition, growth rates
for total employment and population will equal that for basic employ-
ment. If Equations 4 and 6 were nonlinear, the growth rates would
differ among the three variables.
Supply Oriented Regional Growth
The neoclassical model of economic growth provides an excellent
tool for identifying sources of growth when they arise on the supply
side. Consider a regional economy where only one output (Y) is pro-
duced using three factors of production: Capital (K); labor (N); and
resources from the natural environment (L), which include land, air,
minerals, and water. Thus, the production function can be described
as Y = f(K, N, L, T), in which T stands for time and thus dates the
period of production. (T) should be interpreted as a proxy for a given
"state of the art, " and may change from one period of time to another.
The output of product (Y) depends upon the quantities of the inputs
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available for use in the productive process in time period (T) and the
level of technological advance being employed in that period.
Each of the factors is assumed to contribute to output. The respective
marginal products for capital, labor, and the natural environment are
,
' ' and §17'
respectively. Any growth in output between two time periods, say T
and T , can be expressed in terms of the contributions of the various
factors, including technical advance. Thus,
AY = -^ AK + jjjr AN + 3^- AL + AY* (8)
in which AY is the increase in output due solely to technical advance.
Equation 8 can be rewritten as follows:
AY K dY AK N_ 3Y AN L_ dY AL AY1
or
y = ak + pn + €* + t (10)
in -which
AY , _ AK: _ _ AN , ^ AL
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and a, p, and E are respectively the elasticities of production (e. g. ,
a = dY/dK' K/Y) of the factors capital, labor, and natural environ-
ment. Roughly, these elasticities represent the percentage changes in
output that result from a one percent change in the inputs, given that the
supplies of the other inputs and technical advance are unchanged.
In the context of this study, the neoclassical model is particularly
unique in that it would allow the measurement of a change in carrying
capacity (e.g., an increase in the private capital stock or the develop-
ment of a public water resource) to be traced through to its effect on
economic growth. Thus, there is an implication that not only does
growth influence carrying capacity, but that the converse of this propo-
sition is also true.
SUMMARY
To summarize, regional delineation for analysis of carrying capacity
must be based on consideration of the functional elements of three
general types of regional space--the ecological space, the economic
space, and the policy space. To establish manageable units for analysis
within these three regional dimensions, Bahr et al. (1972) suggest the
following criteria: (1) The unit should be relatively easy to identify and
separate from other units, (2) the units should be capable of being
manipulated separately with a minimal effect on other units, (3) the
boundaries of the units should remain within, or resemble as close as
possible, the less discrete boundaries of the ecosystem so that broad
management practices are applicable throughout the unit, and (4) the
movement of materials across boundaries can be measured.
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SECTION VI
CARRYING CAPACITY IN REGIONAL, MODELING
REGIONAL MODELS AND THE ENVIRONMENT
In exploring the relation of carrying capacity to regional resources and
regional structure, a key area of interest is that of regional models.
There are several ongoing modeling efforts in the area of regional
analysis, all of which contain environmental components linked with
other regional social and physical components. Within these modeling
efforts are reflected various approaches to dealing with the problems
of level of spatial detail and the handling of the time (static vs. dynamic)
domain. These questions are of importance in attempting to incorporate
the notion of carrying capacity into models since its potential for appli-
cability ranges from national or broad regional questions (such as the
adequacy of the resource base) to very site specific, spatially detailed
questions (such as the impact of a new industry location on water quantity
and quality of a particular stream).
The primary thrust in looking at proposed or existing regional models
is directed toward the question: To what extent do these models incor-
porate the carrying capacity concept? This question, of course, relates
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to the degree to which these models are sensitive to the character of
changes that will occur under different alternative management strate-
gies of economic activity and types of resource use, whether such
changes are within acceptable limits or tolerances of environmental
and social carrying capacity, and how predicted changes in the physical
environment relate to the social objectives and values for resource use.
This chapter, then, summarizes and compares some of the proposed
and existing regional models. For discussion the models are grouped
under the following categories: input-output based, simulation, exter-
nality, and others.
INPUT-OUTPUT BASED MODELS
Input-Output (I-O) analysis, essentially an examination of the general
equilibrium conditions of production, has been widely used to estimate
the total impact on all sectors of an economy arising from a change in
final demand for the output from any one or perhaps several of those
sectors. For applications within the context of a carrying capacity
model, I-O analysis can be extended to include the estimation of the
residuals associated with any level of production, and more particularly,
measurement of the change in residual volumes when output changes.
Given a vector of final demands for each sector's output, F, and a
matrix of technical coefficients, A, where each a., is the value of
J
input from sector i per dollar of output from sector j, the level of
sectoral outputs (denoted by a column vector, Q) is given by
Q = AQ + F
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Solving for Q yields
Q = (1-A)~1F
in which I is an appropriately dimensioned identity matrix. Assuming
a typical economy characterized by a high degree of interdependence,
the (I-A) matrix will tend to have few if any zero components. Thus,
a change in any element of F will result in changes in all elements of
Q; equivalently, any change in the final demand for one output will
result in changes in all outputs.
Now, virtually any production process results not only in outputs but
also generates residuals many of which have negative values (e. g. , air
and water pollution, noise, etc. ). Assume there are n industrial
sectors and s types of residuals (or pollutants). Construct a matrix,
R, dimensioned (s x n) where each element defines the amount of
each type of s residuals or pollutant (p.) discharged per dollar of
output (q.) produced in each sector. That is,
Now the total level of each pollutant, p., which together form the
column vector p. .., is determined by
(s x 1)
P = R-Q
and since Q = (I-A) F we can determine residuals as a function of
final demand by
P = R(I-A)"1F
72
-------
Thus, not only can any change in final demand be traced through the
system to determine its effect on output in all sectors, the model can
be used to predict the effect of such a change on the levels of all sorts
of residuals associated with that change in production. Clearly this
type of analysis assumes that technology is constant, at least during the
time period necessary for the system to adjust to a new equilibrium;
that it is possible to make empirical estimates in the difficult area of
the residuals matrix R; and that the input-output relationships are
linear. Types of regional environmental models developed from an
input-output base are illustrated by the following three examples.
Residuals Management Models
The core of this model proposed by Russell and Spofford (1972) is an
interindustry input-output model cast as a. linear programming model
which optimizes on an "economic efficiency" objective. Figure 13
illustrates the overall model structure. The linear programming inter-
industry model relates inputs and outputs of various production processes
and residuals generated by the production of each product including
transformation cost of the residuals. The environmental diffusion
model describes the fate of various residuals after their discharge into
the environment. Essentially, these are transformation functions
operating on residual vectors. Finally, the receptor damage model
relates the concentration of residuals in the environment to the resulting
damages. While this model is conceptual, further development and
applications along the lines of residuals-environmental quality manage-
ment have been accomplished by Bower and Basta (1973). The modeling
73
-------
\
-_ ^^ ,_ ^ j
t
OBJECTIVE FUNCTION
Linear industry
model
(Production
processes)
Primary residuals
generated
|
1*
1
1
bu
•a 2
Jg
1
£
1
|
a,
a
3
1
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)
Residual
f|, X
3
$
o
i
2 X
„
Marginal damages
(i.e., shadow prices)
1 1
• •
1 1
Residuals
LINEAR INDUSTRY LP MODEL
I (-
O Xt "fr* O tt Xt ^ .>• ^^Q\ X "" j\« O
II 1 12 2 in n | | ._,
fl2lJCl+fl22-X2+ + a2oX«°?R2 |
1 I
1 8
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i e
i
.Di =* ft Rt i
* J* i*
r\ /Y n \
t>iKj(Ri)
m
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ENVIRONMENTAL MODELS RECEPTOR DAMAGE
(Steady-state, deterministic) MODELS
Figure 13. Schematic diagram of residuals-environmental quality planning model.
-------
approach examines socio-economic activities, analyzing resource
inputs and residuals outputs, the transformation of residuals by environ-
mental processes and the impact of residuals on the receptors. Physical,
technological, and institutional strategies for control are examined and
analyzed as to their effectiveness. The approach has been applied to a
case study in Ljubljana, Yugoslavia.
Ecologic-Economic Analysis Model
This modeling approach (Isard, 1972) places both the economic and the
ecologic systems in an input-output framework and combines them
through an activity analysis of linkages into a single I-O model for the
ecologic-economic system. The key elements are interrelation coef-
ficients between the ecologic and economic activities and their costs.
Cost comparison techniques are used in evaluation of alternative
activities. Optimization with linear programming (LiP) is possible
since interrelation coefficients are readily adaptable to an LP format.
A case study application of the method is made in the selection of
marina site in Plymouth Bay, Massachusetts.
Interindustry Forecasting Model (RFF)
This model developed by Resources for the Future (Herzog and Ridker,
1972) is based on University of Maryland Interindustry Forecasting
Model of Almon. Features of the model particularly relevant to carrying
capacity (see Figure 14) are projections of both natural resource demand
and pollution loadings on the environment, which can be distributed
regionally. These are coupled with submodels for water and air which
75
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LABOR FORCE
UNEMPLOYMENT
EMPLOYMENT
DEMOGRAPHIC ASSUMPTIONS
[ DOMESTIC RESOURCE SUPPLY |
ECONOMIC ASSUMPTIONS J
POLLUTION
GENERATION
RECYCLING ASSUMPTIONS J
ABATEMENT ASSUMPTIONS
REGIONAL-U.S. ALLOCATORS
CITY-REGIONAL ALLOCATORS
URBANIZED
AREA
CHARACTERISTICS
URBANIZED AREA
AIR QUALITY
Figure 14. Schematic outline of RFF model.
-------
can yield water and air quality measures for the future. The suggested
model used is to perform various policy simulation to assess future
impacts.
I-O Models and Carrying Capacity--A Summary
A common feature built into the I-O type environmental models relevant
to the measure of carrying capacity is the ability to assess maximum
amounts of residuals discharged by productive activities during, say,
the production period that can be tolerated by the regional society.
Assume these maximum levels are given by the vector P*. Now, since
P = R-Q
the maximum level of output (i. e. , the region's carrying capacity of
production activities) is defined as that Q, call it Q#, for which
P* = RQ#
Any Q for which RQ > P* will cause residuals to exceed the region's
minimum environmental standard.
As many residuals are associated with consumption (e. g. , driving
automobiles) as well as production activities, the analysis must be
extended to include consumers and their various consumption activities.
As in the production case, this is easily done conceptually, but the
empirical measurement problems are particularly difficult.
Another aspect of input-output analysis in relation to carrying capacity
is the assessment of the effects of technology and rules changes. Tech-
nological developments are occurring constantly, and in recent years
77
-------
more emphasis has been placed on reducing the level of certain residuals
associated with given consumption and production activities. Such
technological change will result in the reduction of one or more elements
of the R matrix of residuals generation coefficients. If all elements
of the P vector are held constant (equivalently, if rules concerning
the maximum level of various residuals released during a given time
period are unchanged) then the decrease in R will imply that the
maximum possible level of production Q* will be greater. Thus, the
dimension of carrying capacity as measured by production and employ-
ment will be increased.
In an analogous manner, changes in institutional rules will also affect
carrying capacity, assuming constant technology. The rules might
change in response to changes in the tastes of the region's inhabitants
or in response to some crisis. For example, an energy crisis might
serve to increase pressure to relax some environmental rules in an
effort to accelerate energy production or to increase use of some of the
more heavily-polluting fuels. Whatever the reason for the change, the
effect on carrying capacity is the same. If the P vector increases
(i. e. , if one or more elements increase while no others increase) then
the region's capacity for production (Q*) will also increase. A
decrease in P, of course, implies a decrease in maximum production.
As above, the analysis must be extended to include consumption activities,
as changes in technology and rules will have a significant impact on
them as well.
SIMULATION MODELS
Modeling is a process of translating physical or social concepts about
a particular system into a set of mathematical relationships for the
78
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various processes and functions occurring in the real system. Simula-
tion involves the use of a model to carry out experiments designed to
reveal certain characteristics of the system. The models should frame
concepts and organize knowledge in such a way that questions relating
to the modeled system can inductively and logically be answered
through a simulation process. Simulation has the following important
assets.
1. The model provides a basis for coordinating information and
the efforts of interdisciplinary personnel.
2. Complex systems can be studied by modeling their separate
parts and by combining their subsystems into the whole.
3. Existing systems can be nondestructively tested, thus proposed
modification to a system can be analyzed without perturbing
the real system.
4. Many planning and management alternatives and proposals
can be studied within a. short time period.
All simulation models have three basic properties: Realism, precision,
and generality. Realism refers to the degree to which the mathematical
statements of the model correspond to the real world concepts they
represent. Precision refers to the ability of the model to predict change
in the system. Generality has reference to the range of situations
where the model is applicable. Since models are imperfect representa-
tions of the real world, they are, therefore, subject to varying mixtures
of realism, precisions, and generality. Whenever a model is constructed,
trade offs must be made between realism and generality, between
79
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precision and generality, etc. , according to the objectives or intended
uses of the model and the data available for model construction.
Validation of simulation models is performed in two steps: Calibration
and verification of the model. Data from the prototype system are
required in both phases of the verification processes. Model calibration
involves adjustment of the model parameters until a "best fit" has been
achieved between observed and computed output functions. Model
testing is an independent test of results achieved over the calibration
phase. During the verification procedure comparisons are made to
test the ability of the model to represent the system of the real world.
The simulation model does not by itself produce an optimum solution
in terms of management objectives. However, the model can produce
a rapid evaluation of many possible management alternatives from a
very large number of possible choices.
Regional Environmental Systems Model
The Oak Ridge National Laboratories Regional Environmental Systems
Model (Craven et al. , 1973) is a simulation model composed of four
basic submodels, socio-economic, socio-political, land use, and
ecological. The flow diagram of Figure 15 shows the interconnection
of the various submodels. The model has been developed and operated
for the East Tennessee Development District, a 16 county area of 6700
square miles centered around Knoxville.
80
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00
NATIONAL AND
SUBNATIONAL
ECONOMIC
ACTIVITY
SOCIO-
ECONOMIC
MODEL
/
REGIONAL
^REGIONAL
REGIONAL
ACTIVITY
ECONOMIC
DECISIONS
"1
1
1
1
SOCIO-
POLITICAL
MODEL
t
ACTIVITY
ATTRACTIVENESS
LAND USE
MODEL
T
i
i
i
1
1
, LAND USE DECISIONS J
LAND USE
PATTERNS i
ENVIRONMENTAL INDICES
*"1
ENVIRON-
MENTAL
INDICES
ECOLOGICAL
MODEL
1
Figure 15. Regional environmental systems model.
-------
The socio-economic model simulates the dynamics of labor .supply
(including population) and labor demand for the modeling region. Pro-
jection of population and employment is the basic driving force of the
model. There are seven components of the socio-economic submodel:
Aging, deaths, births, migration, labor force participation, locally
oriented employment, and regional export employment. A weighted
least square technique is used to fit and test the model's behavioral
relationships. The socio-political model is developed to simulate the
overall impact of the environment on man, society's perception of this
impact, and subsequent management strategies employed by society in
response. The model is constructed to display the interactive and
dynamic relationships which exist between the governmental units, the
general population, and the nonhuman aspects of the regional environ-
ment, expressed essentially as an economic model of government
revenues and expenditures at various levels in the region. The land
use model provides the basis for spatially allocating the regional
population and the employment forecasts and then determining related
land utilization in the region. Liand use indices are used as criteria in
the allocation process; a threshold technique is used in locational
decisions. Finally, the ecological model simulates the burden placed
on the ecosystem by spatially distributed land use activities and the
resulting impact on the environmental quality of the system. The
ecological model consists of (1) an air and water transport model,
(2) aquatic and terrestrial trophic models, and (3) a human activities
model. Key elements are quality of air, water, and stream flow, and
changes in ecosystem due to changes of those qualities. As the descrip-
tion of the model suggests, transferability and application to other
82
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areas is almost a process of starting from scratch because of the many
region specific model characteristics.
Vancouver Regional Simulation Study
As with the previously mentioned model, this simulation study (Goldberg,
Holling, and Kelly, 1971) is also constructed for a specific region. It
is interesting to note both the similarities and differences in the com-
ponent submodels. The demographic model simulates the level of
population in the region. Key elements are birth rate, death rate, and
net migration rate. An economic model looks at the economic activity
of a region resulting from private and public sector spending. Shift-
share analysis combined with inter sectional flows techniques is used for
private sector components. Budget-re venue balancing techniques are
used in public sector components. The transportation model simulates
the effect of a transportation network on growth patterns of the region.
Time-distance is used as the key decision variable. Time-distance is
measured along the most convenient arterial road in the area, in case
of overland travel. The land utilization model consists of four com-
ponents: (1) Agriculture--no detail available, (2) forestry--the relation
of forest products prices, expected return for water, wildlife, and
recreation, (3) recreation--use of central place theory and the theories
of retail location as location criteria for parks in the region, and (4)
urban land use--location of future demand for land use of various acti-
vities types. The health care model determines a quality-of-life index
through measures of morbidity, mortality, and disability. Concepts of
prevention and care are used in developing this model. The model is
presently comprised of four components: (1) Disease generator,
83
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(2) priority streaming, (3) resource allocation for treatment, and
(4) estimation of system benefits and feedback of system shortages.
The pollution model simulates the transportation and assimilation of
pollutants, and their impacts on living systems in the region. There
are four components of the model: (1) Air pollution, (2) water pollution,
(3) solid waste pollution, and (4) ecological impact. Lastly, the human
ecology model, which attempts to devise a means of reflecting the
human impact of changes in the character of the urban system, is
represented by a proposed activity-subculture description as a working
model. The model has been applied in simulating various public policy
decisions for the Vancouver region.
Regional Modeling--Piecewise Simulation
This approach to simulation modeling (Watt and Wilson, 1973) is aimed
at construction of a more general set of submodels which can be applied
to any region specified. Required inputs are basic data for the region
for each of the submodels. The 14 subroutines (see Figure 16) in the
model are structured so as to allow decision makers to simulate certain
policy options and examine their various decision effects. Each subrou-
tine could be considered as a submodel for its designed purpose, but
some of the submodels are also used as a component of a more general
submodel, for example, the pollution submodel or land use submodel,
in the regional simulation. The submodel integration is not carried
out, however, probably due to the intention of keeping the simplicity of
the overall model to facilitate its use by planners and decision makers.
The model has been applied in analyzing the effects of planning policy
in some of the urban centers of California.
84
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COMM1 The main calling routine. Sets flag for
zoning enforcement. User chooses sub-
programs. Demography subprogram runs
automatically.
DEMI Age-cohort survival demography model
gives migration pattern options.
DEMIG1 Performs age specific migration lor
requested areas.
ERESOR1 Uses per capita electrical energy consump-
tion and natural gas consumption. Com-
putes electrical energy consumption for
three categories.
RESTAX1 Uses per capita rates to compute county-
wide expenditures for eight categories.
EMM Optional installation of smog control de-
vices or implementation of rapid transit.
RHOCNG1 Options for building codes regarding maxi-
mum height of apartments and housing
preferences.
EQX Options to separate variables for quality
of life and present them in quantity per
thousand persons, and number of housing
units in unfit condition.
RESDAT1 Option to display data files in tabular
form.
LANINV1 Computes land used through time and
warns user of remaining amount.
KOUCON1 Markov chain probabilistic model for
condition-aging of residential structures.
SOJLWA31 Options for solid waste disposal methods.
Computes land requirement for landfill
and particulate-to-atmosphere from
incineration (if incineration is used).
WATER 1 Computes water requirements for mul-
tiple, single-unit and duplex dwellings.
Computes commercial water use.
RESOR1 Calling routine for resource subprograms.
User options for printout.
Figure 16. REGMOD program flow.
85
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Arizona Trade Off Model--ATOM--
Designed for the purpose of providing information relevant to statewide
policy issues concerning rates of population and economic growth,
changes in composite environmental quality, and distribution of popula-
tion and economic activity, the ATOM (Myers, 1973) model attempts
to portray the trade offs between economic (measured in terms of
employment) and environment (measured by the Battelle (Dee et al.,
1972) system of environmental quality units). Exogenous to the actual
trade off models are (1) a public policy model, (2) an industrial alloca-
tion model which produces a ranked list of feasible industries for 6 by
10 mile grid squares based on location requirements (markets, suppliers,
transportation) and available resources, and (3) a data base on existing
economic, demographic, and environmental characteristics. The
evaluation of trade offs is conducted through the use of several linked
submodels. These are diagrammed as steps 5 through 14 in Figure 17.
First the compatibility of present development with existing or proposed
environmental constraints is tested (steps 5 and 6), and then new levels
of economic activity and their associated waste generation can be tested
against both land use and pollution constraints. K these constraints are
violated, several options are available. One is to select different
industries that would be more compatible with the environment. A
second is to modify the existing level of industrial pollution by the
imposition of specific controls that can be met by industry. A third is
to revise certain of the environmental constraints. Economic impacts
are measured in terms of changes in employment, and environmental
impacts in terms of a weighted set of environmental factors. The
86
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Public
Policy
Regiona l/Industria I
Allocation Model
(RIAL)
Exogenous Submodels
Economic and
Environmental
Conditions and
Constraints
Data and
Trade-off Evaluation
Evaluate Total
Envir onme nta I
±
Total Environmental \ Yes
Constraints Satisfied
13
18
Yes / Are Modifications \ No No / Ig Simulation
Within an Industry ^ M/ Period Completed ?
Feasible? / x
0
Select New
Industries
No
I
10
Environmental Developments\Yes
Constraints Satisfied
ill
Projection
Model
Determine Changes
From Development
.12
Economic Results!
FINAL OUTPUT
14
E n vi r onme nta I
Results
Figure 17. Flow diagram of the Arizona model.
87
-------
change between the two (or the trade offs) can then be displayed for
various policy alternatives. The model is being used by the planning
office of the State of Arizona to explore various planning policies.
State of the System Model--
Of the simulation models discussed, the SOS-1 model (House, 1973; and
Williams and House, 1973) was constructed as a specific attempt to
relate primary and secondary problems of future decisions by coupling
the ecological concept of carrying capacity with the social scientists'
concept of growth, development, and quality of life. The conceptual
form of the SOS-1 model is shown in Figure 18.
In general the driving sectors of the model or the sectors of growth
consist of three components: (1) The population, measured in terms of
physical needs, (2) the private production sector, and (3) the public
services sector. The private and public production sectors are cast in
terms of levels of expenditures for maintenance and production. The
private sector is subdivided into component categories of heavy
industry and light industry, and the public sector into several areas of
governmental services. Each of the production components is mutually
exclusive, and thus independent growth occurs. The population is
partitioned in response to the goods or services being produced by the
production components and age distribution.
The results of the growth sectors take into account the expenditures of
the system for production of various goods and services. This gives
an estimate of outputs provided by each of the production components
(production component output in Figure 18). The production component
output provides a basis for testing the system limiting factors which
88
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o
Comparison Points
— — -> Adjustment Loops
oo
sO
f™*
L .
Population
Growth
JT
\
i
\
1
1
JL
-»
— >
*
-^
>
Private
Pr oduction
Growth
Public
Services
Growth
J^T
Production
Component
Output
r
*
Limit or s &
Constraints
Resources
Eco-Media
Quality
Desired QOL
A
Vy
T^
ii
>i
T «
J-/O
Te
Go
r
x
X
>
"* —
•
ng
rm
als
f
S
>^
r
^
-_ J
Figure 18. Conceptual form of state of the system model (Williams and House, 1973).
-------
consist of resource availability, ecosystem support media in terms of
treatment requirements, and of societal constraints in the form of
demand levels placed on production output components. The comparison
is made at the point noted in Figure 19, and if shortages in resource
availability or deficient quality in the media (air and water) are appar-
ent, the problem is solved through resource substitution, development
of resource reserves, short-term imports, funds redistribution by
adjustment of growth, or lowering of social constraints.
The adjustments made within the system are compared with long-term
societal goals to determine the affect of the adjustments on future
demands fpr resources and the extent to which system population must
'reduce its demand levels. The state of the system is described by
(1) growth of the population size and demands and the levels of funds
available for operating the private and public output sector, (2) the
expected levels of goods and services outputs for each component of
the public and private sector, and (3) the resource depletion, the quality
of the media (air and water), and the quality-of-life measure. If the
carrying capacity is exceeded for the resource base or the quality-of-
life measure, system adjustments are made.
EXTERNALITY MODELS
Another class of models related to regional carrying capacity are those
which consider the externalities that invariably arise as a concomitant
of population and employment growth. The existence of external effects
generally results in a failure of the market to bring about a socially
efficient allocation of resources. In the case of external diseconomies,
90
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Adjust System
Description
Generate System
Description for
Cycle
Growth Sectors
Production Output
Constraints
Long-Term Goals
No
Reset System
for Next Cycle
Solve Problems
Through:
•Resource Substitution
•Resource Reserves
•Short-Term Imports
• Production Technol-
ogy
• Funds Redistribution
• Lowering Demands
mediate
Adiustments
equired?
Adjust Data
and Factors
for the
Future Cycles
Figure 19. Model procedural flow (Williams and House, 1973).
-------
which are easily visible in most urban areas in the form of crime,
pollution, and excessive traffic congestion, the result is general
dissatisfaction among area residents, but no self-correcting forces are
brought into play because individuals are allowed to impose costs on
others without making compensatory payments. The end result is
usually a call for governmental action to establish rules and laws
regulating these externalities. Examples in the pollution field include
requirements that emission control devices be put on automobiles,
prohibition of open burning of trash, and regulation of fuel use to
eliminate or limit the use of highly polluting fuels. On the other hand,
all external effects associated with urban or regional growth are not
of the negative sort. For example, because of the existence of econo-
mies of scale and agglomeration, each new migrant into a growing
area tends to make the city, as a productive unit, more efficient and
tends to increase both average productivity and average wage levels,
thus benefiting all area residents. This phenomenon will be discussed
at the end of this section.
External Cost Rate of Increase--
It can be shown that many types of external costs will rise not in pro-
portion to increased population, but more rapidly--perhaps at a rate
roughly equal to the square of the increased number of inhabitants (see
Baumol, 1967). For example, the dirt, soot, and dust that falls on and
in a person's home as a result of air pollution is a function of the number
of residents in the area. The relationship might well be proportional,
such as
s/h = kn
92
-------
in which s/h is sootfall per home, n is number of inhabitants, and
k is a constant. The number of homes in the area (h) is probably
proportionate to population
h = an
so that total sootfall (s) on the urban population is given by the number
of homes times sootfall per home
s = (an) (kn) = akn
which obviously increases with the square of the population.
A similar example is applicable to transportation. If the average delay
(d/n) on an urban expressway is proportional to the number of indivi-
duals using it (n)
*= bn
n
then total delays (d) or man hours lost is equal to average delay times
number of users
2
d = (bn) • n = bn
According to Baumol (1967), this external cost will tend to increase with
the square of population.
The logic of the argument is simple and perhaps rather
general; if each inhabitant of an area imposes external costs
on every other, and if the magnitude of the costs borne by
each individual is roughly proportionate to population size
(density), then since these costs are borne by each of the n
persons involved, the total external-costs will vary not in
proportion with n, but with n^.
93
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Agglomeration Economics--
In contrast to the above analysis of external diseconomies, virtually
all empirical evidence indicates that productive efficiency increases
with size of city. Such measures as value added per worker, gross
regional product per capita, and wage rates tend to increase monotoni-
cally with the size of the city. The relationship holds even for the
largest cities of the United %tates. The data suggest that increasing
population causes external economies in the form of economies of scale
and agglomeration that result in higher wages for all (Alonso, 1971).
Think of the city as an aggregate production unit where output is defined
as the value of total product of the urban area for both the public and
private sector. Costs will be defined to include not only all private
costs (except labor) associated with production in both sectors but the
social costs (i. e. , negative externalities) associated with urban growth.
A set of product and cost curves for the city is shown in Figure 20.
The product functions have a positive slope consistent with the empirical
data mentioned above while the cost functions are U-shaped to be con-
sistent with both the economic theory of the firm and the models of
external costs outlined above. The return to labor (i. e. , the total
urban population) is the difference between average product and average
cost.
For thfr purpose of defining carrying capacity of a region, four population
levels might be relevant: P , the minimum efficient city size, below
which average cost exceeds average product; P , the city size that
£*
minimizes average cost; P , the population size that maximizes per
capita income; and P , the population size that maximizes the city's
94
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$ /Capita
MC
Population
Figure 20. Urban cost and product curves.
contribution to national output. Depending on whether a local or
national perspective is adopted, population sizes P and P are
•5 Tc
optimal size cities and might be used as an indicator of the region's
economic carrying capacity.
OTHER MODELING APPROACHES
There are, of course, other modeling approaches which are somewhat
divergent from the categories already discussed. A few of these are
noted as follows:
95
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Economic Pricing for Ecologic-Economic
Equilibrium
The basis of the conceptual model development (Koenig and Tummala,
1972) is to identify regulatory and pricing mechanisms that will direct
economic activity toward equilibrium states that are ecologically
feasible. Ecosystem models are constructed from three basic compon-
ents: Material transformation, transport, and storage processes. The
physical and economic characteristics of the system are obtained by
constraining the three "free body" models of the ecosystems by the
laws of materials and energy balance as interconnections among the
three. A model so constructed is proposed as the basis of computation
procedures for analysis of trade offs in the mass-energy and economic
characteristics of the alternative ecosystem designs. Conclusion from
analysis of the conceptual models developed state that:
It is shown that in the face of incomplete information on
"environmental capacities," it is possible to "hedge" against
certain classes of uncertainties through the use of pricing
mechanisms.
Environmental "Bookkeeping"
This accounting type of approach (Deitchman, 1972) is offered as an
alternative to other types of I-O and simulation models because of the
time and difficulty in constructing them. It suggests that if better data
were available to describe elements of pollution then better control
decisions would be taken. The bookkeeping approach would be used to
present decision-making bodies with a number of summary lists
including:
96
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1. Consumer products from production processes that also
produce wastes (pollution), which in turn enter air, water,
and land;
2. The direct costs of producing and distributing those products;
3. The negative effects of those wastes on the sinks; and
4. Measures of quality of life in the presence of those pollution
effects.
The proposed approach, according to Deitchman would permit society
to make comparisons of the changes that pollution control can bring
about in products, effects, direct costs, and measures of quality of life.
The results of the social decision processes would then be determined
by the value judgments of various parts of society based on those
comparisons, and the subsequent social and political dynamics.
Postscript on Regional Modeling
Of the models described, a comparative examination reveals that most
of them have elements or features which are related to at least some
of the basic definition and the operational elements of a human carrying
capacity concept for regional planning. Likewise, they contain assump-
tions and procedures which do not fit well with either spatial or temporal
problems that must be addressed by the concept, or the social-cultural
aspects of trade offs among production components that constitute the
human environment and aspects of the natural environment.
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SECTION VII
A CARRYING CAPACITY PLANNING PROCESS FOR
REGIONAL ENVIRONMENTAL MANAGEMENT
INTRODUCTION
The concept of carrying capacity offers a fresh view of problems
related to regional organization of man1 s activity in relation to the
environment. Carrying capacity, as defined, is a limit and boundary
oriented concept. Relative to resources, it emphasizes that programs
and activities must be managed within the capabilities and capacities
of natural and human environments to accommodate change and still
retain their stability and resilience. It takes note of the net effect of
past policy decisions and raises questions about future implications of
present policies and actions by asking appropriate questions about the
carrying capacity of the environment for future actions and activities.
There is a great need for effective regional and local response to
forces of change that will impact significantly on resource utilization
and growth of regions of the country. The key question related to
carrying capacity is: How can such forces of change, both external
and internal to the region, be managed, guided, and controlled so that
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growth (or decline) in region's activity sectors will occur in an orderly
fashion and in such a manner that 1) demands upon the resource base
do not exceed supply potentials or assimilative capacities, and 2) levels
of production of goods and services, both public and private, for
desired quality-of-life levels are maintained?
In examining the capability of a region to sustain existing and proposed
activities, consideration must be given to the elements which circum-
scribe the domains of carrying capacity in a region--the character and
extent of the resources, the functions and structures of the region, and
the people and institutions. Within this setting, this chapter seeks to
articulate a planning process which is based on the concept of carrying
capacity as it interacts with the decision-making aspects of regional
environmental planning. The description of the process is intended to
lay a foundation for interdisciplinary cooperation in regional planning
and decision-making processes which affect all aspects of the environ-
ment. Within this planning framework, models and analytical tech-
niques can be usefully integrated as tools to predict the response of
the environment to proposed changes in a region, and to analyze
regional environmental impacts in assessing overall environmental
soundness of alternative policies.
SPECIFICATIONS FOR CARRYING CAPACITY -
BASED PLANNING PROCESS
Typically the content of information required for planning or policy-
making is dictated by the nature of the problem addressed and the
questions asked by the decision maker. However, information quality,
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especially its reliability and credibility, can be significantly affected
by the manner in which it is developed and by the spatial and temporal
contexts in which it is arrayed. For these reasons it seems appro-
priate to provide a set of specifications for information provision as a
framework for structuring a carrying capacity-based planning and
management process.
Spatial Context
Typically decision information boundaries are not coincident in either
time or space. Therefore, successful development and implementation
of any quantitative approach to information provision and planning must
have capability for providing information on capacities of both natural
and human environments at various levels of spatial resolution. Plan-
ning information is usually developed for a wide range of purposes not
all of which can be properly considered within a given "ideal" region.
Friedmann (1966, pp. 227-228) states that:
Although most regional objectives require formulation
in terms of a given set of regions, the specific regional
relationships calculated from available data can represent
any reasonable aggregation of activities and interactions
across space. The basic task is to ensure the availability
of statistical data on a comparative basis for the smallest
area unit which can be advantageously used in spatial
analysis. . . . From these considerations it follows that
I am opposed to efforts to impose a qua si-official region-
alization upon the United States. . .. Experience with
such efforts has not been satisfactory, despite repeated
attempts to discover the one "true" set of regions. Full
agreement is never obtained for any set of criteria for
regional delimitation; not only will every investigator
wish to alter boundaries to suit his ends, but all criteria
quickly lapse into obsolescence.
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The importance of this specification is emphasized further by Berry
(1966, p. 58) in his critique of the suggestion that functional economic
areas (FEA1 s, COG' s, and multicounty regions) are more or less
"ideal" planning regions. He summarizes as follows:
First, an understanding of how the economy is organized
in geographic space is essential. A regionalization may be
useful if it contributes to such an understanding. Some
regionalizations are more useful than others; Karl Fox has
emphasized what may perhaps be the single most useful
regionalization of the country.
Second, to use a set of regions in the planning process
one must have goals in mind. On this score Fox1 s set of
functional economic areas (FEA1 s) has little to offer. One
can describe FEA1 s as of central importance in the economy.
Yet it cannot be said that understanding and using them in
the planning process necessarily insures that predetermined
ends be served. One should not claim too much. It may be
that a different set of regions will be necessary to satisfy
each set of goals for each different policy.
Noncongruencies in decision information boundaries appear to exist
between and within the subsystems of human and natural environments.
Certainly the boundaries of watersheds, and air sheds seldom coincide
in the natural environment and it is equally unlikely for policy imple-
mentation spaces and functionally defined socio-economic units to
coincide in the human environment. Thus it is imperative that an
aggregative-disaggregative capability be an integral element in the
assembly and display (including modeling forms) of planning infor-
mation. Inherent in this specification is the idea that planning infor-
mation for small regions must be generated within a consistent
macro-regional context. Alternatively, capability should exist to
evaluate the cumulative impact of changes initiated outside the macro-
region to be traced to small regions.
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Temporal Context
The context for information provided by a consideration of alternative
time paths is deemed an important characteristic to be included as a
specification for carrying capacity decision information. Viewing
information in a comparative static reference frame shows only the
beginning and the end points of change, but depicts none of the evolu-
tionary processes which lies between them. To do this requires
knowledge of the basic behavioral, technical, and definitional relation-
ships among them. Further, it would require knowledge of any
changes in these relationships as the system evolved through time.
Obviously complete knowledge of this sort is virtually impossible to
obtain. However, several abstractions are available at the national
and regional levels which provide useful precedents for incorporating
this dimension.
An explicit and possibly the least arbitrary means for assessing the
time distributions of planning information is to impose alternative
exogenous influences in varying sequence and magnitude on pertinent
systems (subsystems) in the human and natural environments. If the
structure of the system varies predictably or remains constant over
time, differences in system outputs can be associated with changes in
exogenous forces (inputs). In either case the time path of impacts on
a system can be traced by examining a range of "realistic" alternative
futures. As in the case of spatial context, the content and resolution
of decision information will be dictated by the problem addressed or
the question asked by the planner or decision maker.
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Implementation Context
The implementation context as specified for a carrying capacity-based
planning process is defined in much broader terms than is typical with
formal model construction. For example, implementation is deemed
to include phases dealing with data assembly, estimation of analytic
relationships and integration of suitable models and techniques, and
sensitivity and reliability testing. Procedural phases specified in
implementation include 1) identification of pertinent systems and
appropriate decision boundaries in human and natural environments
which will affect or be affected by a contemplated decision or policy,
2) selection of specific spatial units (building blocks) to be used in
supplying a data base, 3) assembly and/or estimation of system
structure in forms suitable for testing, 4) experimentation and sensi-
tivity testing to determine effectiveness of plans and solutions, and 5)
assembly of information outputs into forms suitable for translation to
target user groups.
Decision-Maker Role
The interactivity of planners and decision makers (users) is critical as
a specification for a carrying capacity process in two ways. First,
the process should allow planners and decision makers to fully interact
with the analytical models and techniques used as vehicles in the
process, and second, the process should stimulate interaction among
planners and decision makers themselves. The first point recognizes
that the usefulness and application of analytical devices and the
decision information they generate is greatly enhanced if provision
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exists for frequent interaction by the user and researcher throughout
the development and implementation stages. It is not unusual, for
example, to find complex planning models developed in isolation from
the ultimate users of the information. As a result, models fail to
address interesting questions at a level of resolution that is helpful to
the user. A planning process utilizing carrying capacity-based infor-
mation must have a high degree of planner-decision maker participation
to assure the continuity of data measurement and refinement of analyt-
ical techniques.
The second consideration of the decision-makers role in the specifica-
tion of a carrying capacity-based planning process relates directly to
the capability to "weigh" trade offs in capacity changes between desired
and prevailing conditions in the human and natural environments. Strong
interactive capability of potential information users assures a higher
probability of important trade offs being articulated and a lesser degree
of polarization among contesting interest groups. These results can
be expected to the extent that the decision makers become better
informed as a result of their interaction with each other, the planners
and public, and their exposure to more complete information concern-
ing the consequences of their actions.
CONCEPTUALIZATION OF A CARRYING
CAPACITY PLANNING PROCESS
In general, the goal of planning can be seen as an effort to provide a
desired array of "quality-of-life" elements through physical and
social design of the human environment. In accomplishing this goal,
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the planner has traditionally worked within the limits of what is
engineeringly and economically feasible and what is socially, politically,
and legally acceptable. Usually, the planner has not examined the
degree to which physical and functional plans are tied to ecological
systems for resource supplies and for residuals assimilation (Cooper
and Vlasin). As House (1973) puts it, plans "need to be tested for
realism under situations of limited resources and established environ-
mental qualities. That is, they must be related to a regions carrying
capacity. "
The processes that affect the overall quality of the environment are
economic and social for the human environment and evolutionary for
the natural environment. The carrying capacity concept, as defined
earlier, recognizes that in order to improve the "quality of life"
relative to both natural and human environments, the pattern and level
of production and consumption activities must be compatible with the
capabilities of the natural environment, as well as with social prefer-
ences. Recognizing that society is a composite of a wide range of
values and expectations, clearly conflicts will exist between consump-
tion associated with desired life styles and feelings for the future con-
ditions of the natural environment. To reconcile the attitudes and
expectations for the human environment and the quality and stability
of the natural environment, a planning process and analytical
mechanisms need to be developed that will provide a way to equitably
balance the two.
The carrying capacity planning process described in this section is
conceived as a means for resolving conflicts and making trade offs
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necessary to converge on socially and economically viable and environ-
mentally sound decisions as to future growth and development. As a
process, rather than a model, it strongly emphasizes the planner-
decision maker-public interaction in formulating plans for managing
the natural and human environment.
The process, as presented in Figure 21, logically breaks down into
five major component processes for examining changes in human and
natural environmental carrying capacities which result from exogenous
and endogenous growth forces in a region and the plans to direct them.
The carrying capacity planning process, then, serves to integrate and
trade off social expectations with ecological and resource capabilities
to derive carrying capacities for quality human and natural environ-
ments. The following paragraphs briefly set forth the five functional
components of the process.
Alternative Futures Description
of Regional Driving Forces
The use of alternative future descriptions of regional driving forces as
a component process in carrying capacity planning follows naturally
from the implications of three of the process specificiations previously
elaborated. First, the need to deal with varying regional boundaries
for carrying capacity information necessitates a flexible and open
approach for dealing with forces of environmental change that are
exogenous to the region. These forces 'cannot be explicitly controlled
•within the region, yet an understanding of them and their effects
internal to the region are of vital importance to regional carrying
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Exogenous
Change-
Alternatives
Futures
I
fConti
i
-**
ol
/
• r
NATURAL ENVIRONMENTAL SYSTEM
REGION SYSTEMS DESCRIPTION & ANALYSIS
s
RESOURCE
INPUTS
Natural
, Resources
Human
Resources
i
of\ /
-H —
-
-
MODELED SYSTEM
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(
Physical
Biological
System
,. T
Social
System
Economic
Demo-
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— t:
i
=$
Realized
Changes
In Carry-
Ing Capacity
Indicators
Supply /
Demand
Change
Intra-
structure
Congestion
Changes
Resource
Availab-
ility
Resource
Use
Changes
Assimilative
Capacity/
Residuals
Changes
^
0
Carrying
Capacity
Differentials
CARRYING CAPACITY BASES -
MEASURES AND INDICES
, _t
^
1
Naturally
Determined
Capacity
f Assimilated
Capacity
Use
" Levels
1 Socially
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_^ : H
HUMAN ENVIRONMENTAL SYSTEM
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lable\
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4 / Socialization \
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Change In
Environmental
System
Structure
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Maker
Interactions
Tradeoffs
Controls
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Socially
Acceptable
Capacity
Levels
Figure 21. Representative of the carrying capacity planning process.
-------
capacity changes. In this regard attention must be given to events or
actions of exogenous change which originate either outside, or at some
point within the regional information boundaries.
Second, the need in the temporal dimension to examine transitions to
future states directly points to the use of alternative futures con-
structed of various combinations of possible future events. Alternative
futures describe a range of plausible future states affecting the natural
and human environment against which the adequacy of plans for the
management of regional carrying capacity can be tested. In contrfst,
projections rely, to greater or lesser extent, upon extrapolation of
trends in those areas for which data is available. The danger of such
projections is that the future cannot be relied upon to follow past trends,
Planning based upon such projections, therefore, .may be oriented
towards meeting or anticipating conditions that do not come to pass.
On the other hand, alternative futures provide descriptions of possible
sets of future conditions, and should offer insight into likely levels or
magnitudes of "demand" for system outputs. Since shifts in demand
are expected in response to such factors as changes in income, popu-
lation, and leisure time, alternative descriptions of possible future
levels of various demand determinants are essential when estimating
the probable total magnitudes of change (Bishop, 1973). Hence,
emphasis is not placed on producing a forecast, but on identifying the
effects of change.
Third, the need for a high degree of planner-decision maker-public
interaction in the process is also well served by consideration of
alternative futures as regional driving forces. The alternative futures
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approach places emphasis upon so-called "adaptive planning, " in which
there is direct and active participation of the decision maker in the
planning process. Thus, the alternative futures technique stresses
participation over an analysis solely dependent upon modeling tech-
niques, and focuses on the planning process rather than the "plan" as
the total product of the planning effort.
Regional Systems Description
and Analysis
The determination of changes in regional carrying capacity realized as
the result of alternative future driving forces and environmental
management plans is the product of the descriptive and analytical
capability within this process component. This process function, in
effect, operationalizes the specifications dealing with hierarchical
levels of spatial detail, temporal dimension of tracing out the time
paths of carrying capacity measures and indicators, and implemen-
tation which draws on existing data and provides for testability and
sensitivity analysis. These specifications provide the essential
groundrules for integration of modeling capabilities and techniques
for predicting changes in indices of natural and human environmental
quality resulting from regional environmental management plans. The
perspective of this process component given by Figure 21 is of three
general elements: Resource input changes, systems models and
analytical techniques, and an output vector of realized changes in
carrying capacity indicators.
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The system inputs describe the relation of the driving forces to the
resource base, and hence the required resource data. This includes
physical resources and inputs to production, media qualities and
assimilative capacities, and relevant socio-economic and demographic
information.
The systems models and analytical techniques are an integration and
linking of working models and tools to analyze resource allocation and
capacities, and the environmental impacts of alternative futures driving
forces. A comprehensive picture of the analytical relationships and
levels of spatial resolution in determining carrying capacity changes
is presented in Figure 22. The diagram recognizes four primary
levels of modeling and analysis representing progressively higher
degrees of spatial resolution, linking the resource input changes from
the driving forces to the changes in carrying capacity indicators.
Beginning at a broad regional level, economic and demographic models
describe production, consumption, and resource exchange within the
region in terms of required natural resource, raw material, and social
infrastructure inputs, on the one hand, and the outputs of goods and
services and residuals, on the other. These four classes of resource
state .changes, associated respectively with resource base, social
system, economic system, and resource media and ecological system,
are operated on by a series of "models" representing higher degrees
of spatial and temporal resolution. These models and analytical tools
include materials transformation models, distributive spatial and
temporal models, and finally, human and natural environmental impact
models.
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Alternative
Future
Driving
Forces
-»•
Economic
and
Demographic
Models
Production
Consumption,
and Exchange
ECONOMIC AND
DEMOGRAPHIC
MODELS &
TOOLS
/
\
-*.
h
Goods
Services
Social and
Infrastructure
Inputs
Labor ,
Knowledge ,
Capital
Investment,
Infrastructure
Natural
Resource
Inputs
Raw Materials
Re- Cycling
Residuals
Trc
me
MATERIALS
TRANSFORMATION
MODELS*
*Includes
Imports &
Exports
atr
nt*
i
Distribution
of
Goods and
Services
Densities
Population,
Industrial,
Land Use,
Infrastructure
Resource
Extraction
Patterns
Distribution
(Loadings)
of Wastes-
Residuals
DISTRIBUTIVE
SPATIAL AND
TEMPORAL
MODELS*
"rlntra Regional
HUMAN
^
IMPACT
Economic
Impact
i
\
r
Social
Impact
*
w_
^
Reso
Base
Imps
t
\
Medl
Ecos
Imp a
urce
ct
t
»
a and
ystem
ct
ENVIRONMENTAL
IMPACT
ENVIRONMENTAL
IMPACT
MODELS
^
^—
SUPPLY / DEMAND
CHANGES
INFRASTRUCTURE /
CONGESTION
CHANGES
RESOURCE AVAILABILITY/
RESOURCE USE
CHANGES
ASSIMILATIVE CAPACITY /
RESIDUALS
CHANGES
CHANGES IN INDICES
AND INDICATORS
Figure 22. Relation of modeling and analytical techniques for carrying capacity.
-------
The outputs from these successive levels of modeling and analysis are
changes in the capacity measures or indicators for four general classes
of indices, viz., supply and demand, infrastructure and congestion,
resource use and resource availability, and waste loading and assimila-
tive capacity. This vector of capacity changes summarizes and dis-
plays the implications of future actions and their higher order effects
in light of limited resources and environmental qualities, the changes
or shifts in infrastructure and land use (congestion), and the distri-
bution of goods and services that would result from activities associated
with the alternative futures. These output measures of resource capac-
ity, then, provide the basis for examining the effects of carrying capac-
ity constraints and limits that will impinge upon, affect or regulate
events and activities associated with alternative futures. For example:
1. Environmental standards, controls, regulations,
2. Resource limits and capacities (rate of use, depletion of
stocks, assimilative capabilities, resource recovery and
recycling, discovery of new resources and improved
efficiency in production through technology, and sub-
stitutability of resources), and
3. Social and institutional factors (demands for goods and
services, attitudes toward conservation and environmental
protection, etc. ).
Carrying Capacity Bases; Measures and Indices
This process component deals with the problem of measuring the out-
puts of productive activity and utilizing these measures to assess the
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carrying capacity of a region. As Figure 22 indicates, production
outputs may be divided into two classes: (1) Goods and services and
(2) wastes and residuals. Measurements for the former (social indi-
cators) may be used to gage the relative change in human productive
and social processes. Measurements for the latter (environmental
indicators) allow managers and decision makers to determine how
productive activity affects the quality, assimilative and future produc-
tive capacity of the receiving environment.
To describe considerations in measurement of change in human and
environmental capacities, several definitions will be helpful. The
term "indicator" is used to represent any measurement of conditional
states or changes in states in human and natural environments (e. g.,
amount of BOD or SO_, number of cars recalled annually, number of
reported crimes). Several indicators may be integrated into a single
index for more complex conditions or components (e. g., air quality,
consumer price index). Indices at an intermediate level of aggregation
may, in turn, be integrated into still more general indices (e.g., GNP,
quality of life, environmental quality). The term "index, " then, is
used to represent a measurement of some environmental or social
component for which there is more than one indicator. It should be
noted that such aggregated components cannot be measured directly.
Through the use of an appropriate indexing function and measurements
for its indicators, however, these components can be measured
indirectly.
Indicator/index research has been undertaken as a means of organizing
technical and particular information into more generally understandable
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and practically useful information. The Third Annual Report of the
Council on Environmental Quality (CEQ) characterized this concern:
One of the most effective ways to communicate infor-
mation on environmental trends to policymakers and the
general public is with indices. An index is a quantitative
measure which aggregates and summarizes the available
data on a particular problem. . . The nature and complexity
of the index will depend on the subject matter and the
purpose the index is to serve.
Information on the environment can be presented to the
public in a format which lies anywhere along a continuum
ranging from the raw data at one extreme to a single index
number for the whole environment at the other.. . The use
of a limited number of environmental indices, by aggre-
gating and summarizing available data, could illustrate
major trends and highlight the existence of significant
environmental conditions.
The work of CEQ may also be characterized as an effort to develop
means for measuring progress towards environmental quality standards
and as a way for assessing the success of Federal, State, local, and
private environmental protection activities.
In general, the work on indicators has been conducted under two
general conceptual perspectives. One perspective views indicators
as a means of assessing progress towards the attainment of social
(or environmental) goals, or, alternatively, of quality of life (or
environmental quality) norms or standards. Some contend that this
stresses ideal conditions and is heavily value laden. Thus, a variation
on this general approach views indicators as a means of measuring
progress towards the achievement of social and environmental mini-
mums, i. e., the basic survival needs of human and nonhuman popu-
lations (Corning, 1971).
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The second conceptual perspective considers social and environmental
indicators in a systems framework. Land (1971), for example, views
social indicators as statistics-that "(1) are components in a model of
a social system, (2) can be collected at various points in time and
accumulated into a time-series, and (3) can be aggregated or dis-
aggregated to levels appropriate to the specifications of the model. "
He suggests the generation of social system models of such social con-
ditions as poverty, health, leisure, and education. More ambitiously,
Fox (1969) sought to develop procedures for quantifying inputs and
outputs in social systems, developing a gross social product, and iden-
tifying what variables might need to be considered in such an analysis,,
Efforts to utilize indices in a systems framework have met with some
success in micro-economic and environmental modeling efforts. In
fact, it appears that an amalgam of these two perspectives would be
most useful in developing indices for use in a carrying capacity-based
planning process. Typically the very large number of state con-
ditions in human and natural environments become more or less
incomprehensive to both laymen and decision makers. This con-
fusion may be attributable to an over abundance of seemingly unrelated
state conditions and the apparent lack of contextual bases for these
conditions. As suggested above, indexing is specifically designed to
provide a realistic condensation (indices) of various state conditions.
Additionally, the contextual problem can be reduced by linking indices
to pertinent systems and data bases which maximize their information
context. In some instances, the appropriate index/system linkages
can be suitably depicted by formal modeling approaches, while in
others more heuristic analyses and approaches may be required. In
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any case, an analysis of regional carrying capacity will require a
systems approach and utilize indices to provide information concerning
capacity changes in the human and natural environments. The formal
identification of these index/system relationships is depicted in
Figure 21.
Note that this figure is divided into three components. On the left is a
schematic representation of index/system relationships labeled region
systems description and analysis. This component reflects the
essential linkages between "realized" carrying capacity indices and
the structural system(s), resources, and exogenous driving forces.
An essential distinguishing feature concerning the information output
of this component is that it depicts realized changes in carrying capac-
ity, and therefore is analytic and descriptive in nature. On the right
is a second set of index/system relationships labeled carrying capacity
bases. This process component reflects the essential linkages between
desired or "ideal" indices of carrying capacity and elements of the
human and natural environment. Thus it provides a symmetric variant
of the regional systems description differing from it because of the
normative character of the indices. Technically, the two sets of
indices, descriptive and normative, could be identical in which case
the center component carrying capacity differential would not exist.
However, this is not expected to be the case. Rather, this center
component focuses attention on shortfalls, excesses and trade offs
which typically exist between descriptive and normative indices of
carrying capacities. It is this focus which provides operational
objectives for a carrying capacity-based planning process and facili
tates identification of management (control) strategies and their inter-
vention points among the components of the process.
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Thus if carrying capacity indices of the sort described above could be
developed such that qualitative changes in human and natural environ-
ments could be monitored in a carrying capacity planning process, a
basis would exist for evaluating the performance of regional systems
in terms of pertinent indices of carrying capacity changes and their
divergence from "ideal" magnitudes for the same indices.
A considerable effort has been directed toward the development of
descriptive and normative indices of both the human and natural environ-
ments. Since such indices represent possible measures for carrying
capacity changes the following paragraphs briefly summarize and pro-.
vide examples of some of the current work in the area.
Natural Environment Indices--
In the natural environment, for example, the CEQ reports that
"progress in developing indices for air pollution is more advanced
than in any other environmental area. " Under CEQ contracts, the
Mitre Corporation has developed two indices for assessing trends in
s
air quality: The Mitre Air Quality Index (MAQI) and the Extreme
Value Index (EVI). Another index-^the Oak Ridge Air Quality Index
(ORAQI)--has also been developed by the Oak Ridge National
Laboratory.
Other indices are being or have been developed for other areas of
environmental concern, notably water pollution, pesticides, toxic
substances, land use, and wildlife. For each of these areas, CEQ
has identified what it assumes are the critical indicators. Once
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satisfactory indices can be developed for the above areas 6f environ-
mental concern, intermediate level indices will presumably be aggre-
gated into an overall environmental quality index. Such an EQ index
for the nation has been developed by the National Wildlife Federation,
and on a regional scale, the County of San Diego plans to develop an
EQ index and has made substantial progress in developing requisite
subindices.
The state of the art in the development of particular environmental
quality indices and the establishment of monitoring systems to provide
requisite data for the calculation of these indices appear to warrant
the conclusion that it appears feasible to incorporate such environ-
mental quality performance criteria into a carrying capacity-based
planning process.
Human Environment Indices--
Numerous similar efforts have been directed toward the development
of indices relating the condition of human environments for a variety of
region types. Essentially these are designed to evaluate the perfor-
mance of social programs and institutions in providing for the needs,
desires, and aspirations of various publics and of assessing how index
levels effect and are affected by other variables in the supporting
system(s). A first step in exploring this problem involves identifying
carrying capacity indices in the human environment. Such a list might
be comprehensive and complete, or it might be partial and repre-
sentative, depending on the type of question or problem under
consideration.
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The Technical Committee (1971) effort to develop the "Strawman" is a
good example of the comprehensive approach. In this study, an inter-
disciplinary task force identified nine general social goals descriptive
of the human environment (collective security, environmental security,
individual security, economic opportunity, cultural and community
opportunity, aesthetic opportunity, recreational opportunity, individual
freedom and variety, and educational opportunity), disaggregated
these goals into several tiers of subgoals, and identified social indi-
cators under each lowest-level subgoal. This hierarchical array is
intended to approximate what is meant by the phrase "social well-being."
To illustrate, the tentative disaggregation of the economic opportunity
goal is provided in Table 3. Taking a less comprehensive indexing
approach to evaluate the outputs of productive activity, a "community
attractiveness profile" might be developed using only a few critical
indices.
The "state of the art" in indexing techniques appears to be sufficiently
advanced to warrant their incorporation in an analysis that would relate
productive activity (public and private) to quality levels in both the
human and natural environments. Indices can serve the purposes of
examining how environments are affected by productive activity and
how, in turn, the relaxation or upgrading of these norms affect produc-
tive capability through time.
Carrying Capacity Differentials and Adjustments
The tests of usefulness for a carrying capacity-based planning process
are found in the capability of such a process to 1) articulate differen-
tials (short-falls, excesses, trade offs) between "desired" (normative)
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Table 3. DISAGGREGATION OF THE "ECONOMIC
OPPORTUNITY" SOCIAL GOAL INTO SOCIAL
INDICATORS (TECHCOM)
A. Present standard of living
1. Median per capita income
2. Prices of goods and services
--Cost of Living Index
--Consumer Price Index
3. Quality of goods and services
--Repair costs per capita as a percent of purchase price
--Cars recalled annually as percent of total
4. Selection of goods and services
--Percent change in the number of new patents issued
--Retail employees per capita
--Retail per capita sales receipts
5. Leisure time
--Average weekly working hours
--Per capita receipts of amusement and recreation service
e stabli shment s
--Per capita attendance at State Parks
--Per capita sales of hunting and fishing licenses
6. Stability
--Percent growth rate of per capita income
--Inflation rate
--Unemployment rate
--Business failures as a percent of the total number of
businesses
B. Future standard of living
1. Employment potential
--Employment growth rate (percent)
--Unemployment rate (percent)
--Net migration as a percent of total population
--Median education level (years)
- -Median income growth rate (percent)
2. Savings and investment potential
--Economic growth rate (percent)
--Population growth rate (percent)
3. Retirement potential
--Social insurance contributions per capita
--Private insurance contributions per capita
C. Equality of economic opportunity
--Gini coefficient for income distribution by income class
--Median education for ethnic groups
--Employment rate for ethnic groups
- -Ratio of female unemployment rate to male unemployment
rate
The items prefixed by dashes (—) are social indicators.
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and "realized" or descriptive (empirically determined) changes in
carrying capacity indices, and to 2) identify intervention points for
initiation of various control or management strategies. Obviously a
recognition of divergence as between "real" and "desired" carrying
capacities, or changes in them, is basic to the identification of
appropriate and effective management strategies. "Desired" levels of
supply/demand satisfaction must necessarily be weighed against
"realized" changes in congestion, resource availability and waste
assimilative capabilities. Likewise, "desired" indices reflecting
important features of the material environment or changes in them,
could be arrayed against "realized" indices of economic and social
well-being.
Although this approach suggested a certain degree of polarization
between interest groups if they align themselves in terms of potential
trade offs among different indices of carrying capacity, the inter-
activity usually associated with an articulation and weighing of these
trade offs should enhance communication and the understanding of the
consequences of their respective decisions. This interactivity among
decision maker, planner and researcher in all phases of the planning
process will influence the mix and focus of control strategies because
commonality of interests can more easily be identified, thus reducing
the necessity of employing coercive management strategies.
As depicted in Figure 21, decision-maker interactions are considered
the key element in implementing alternative carrying capacity manage-
ment strategies in response to recognized differentials between
pertinent indices of "realized" and "ideal" carrying capacity. Three
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basic strategies emerge, falling roughly into the categories of atti-
tudinal, institutional and informational. Obviously these are not
mutually exclusive, and depending upon the situation being addressed
may be most effectively applied in concert. Four intervention points
have been identified in Figure 21 for the application of these strategies.
The first is directed toward changing or controlling the magnitude,
timing or location of exogenous driving forces. For example, a recog-
nized differential or short-fall between "realized" and "ideal" indices
for air quality may be effectively controlled by imposing restrictions
on neighboring regions whose particulate wastes are currently being
exported into adjoining regions. Alternatively, export taxes could be
employed to discourage production of those export commodities which
contribute significant quantities of particulate matter to the regions
air sheds. Such measures fit roughly into the institutional category of
management strategy. Institutional measures may be implemented
either by mutual consent or by probationary-coercive means, depend-
ing primarily upon the extent to which decision information identifies
interregional commonality of interest. Commonality, of course, is
not always present, but the availability of information facilitates its
emergence and thus serves to diminish the likelihood of interregional
conflicts.
The second and third intervention points are in the areas of system
structure, denoted as region systems description and carrying capacity
bases in Figure 21. In these cases, carrying capacity differentials
are addressed by introducing measures designed to change the basic
structure of the system such that input/output conversion rates are
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altered in desired directions. Such a strategy is basically infor-
mational in character and seeks to introduce improved technologies,
or more efficient management, in areas of the indices for which a
carrying capacity differential exists. In some instances, a similar
modification in structure may be introduced only by using institutional
strategies in combination with informational forms to induce or coerce
the adoption of technologies which would not otherwise be used.
Common examples are provided by legislated standards on air and
water effluents and the various residuals tax and subsidy schemes.
The latter are highly flexible means for changing relative prices and
hence input/output relationships in production systems which in turn
govern carrying capacity indices.
Finally, and perhaps most importantly is the intervention point in the
area of soil tastes and tolerances. The strategies assignable to this
area are basically attitudinal in character but would typically include
use of some elements of institutional and informational forms. Impor-
tance is assigned to this control means because of its obvious presence
in establishing "ideal" indices of carrying capacity. Socialization and
educational processes, as well as material well-being influence
socially determined carrying capacities, especially in relatively
\
affluent societies in which subsistence needs are easily filled.
Ideal carrying capacity indices are most susceptable to change and
are perhaps the most volatile of control measures for eliminating
carrying capacity differentials in regions and societies where there
is extensive mass communication. This does not necessarily mean
that carrying capacity differentials based on "ideal" limits can be
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readily changed by propagandizing the human population, but rather
that given time and sufficient exposure, those capacities which involve
tastes and preferences of higher order, can be and typically are con-
ditioned by information.
THE CARRYING CAPACITY PLANNING PROCESS
AND ENVIRONMENTAL MANAGEMENT
In developing environmental management strategies for the urban
region, planners and decision makers must continually assess the
social and environmental implications of various proposals. Recog-
nizing and establishing the limits or capacities of regional activity
support systems along the lines of the carrying capacity planning
process described in this chapter could provide decision makers with
a workable approach to assessing the natural and human viability of
proposals.
Indices have begun to develop as a means of providing a working
knowledge of environmental quality, and of charting trends and changes
in quality levels. The development of carrying capacity concepts can
extend the usefulness of these indicators beyond just showing trends
in to the realm of making comparative evaluations of environmental
quality dimensions in terms of ranges and limits of acceptable levels,
and the impact of various regional growth policies.
Regional environmental management which incorporates a carrying
capacity planning process can thus be used to examine the character
of changes that will occur under different levels of activity and types
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of resource use, whether such changes are within acceptable limits of
environmental and social carrying capacity, and how predicted changes
in the physical environment relate to the social objectives and values
for resource use.
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SECTION VIII
APPLYING CARRYING CAPACITY IN A
LOCAL URBAN SETTING
CARRYING CAPACITY IN
PLANNING ACTIVITIES
This chapter will trace some of the implications of the carrying capac-
ity concept for planning at the local level. Viewed against the planning
perspective sketched in the last chapter, it seems fair to say that plan-
ning at the city or county level can accommodate carrying capacity
considerations if it involves: 1) Identifying those events and decisions
(driving forces)--present and future, local and remote--that will likely
result in significant local changes, 2) inventorying existing conditions
to establish baseline data for the area's natural and human resources,
s~ *
3) estimating how existing conditions will be modified by the driving
forces, 4} formulating alternative policies and programs for dealing
with such change, 5) estimating the trade offs that would be involved
among the alternatives as a basis for deciding on best courses of action,
and 6) implementing these decisions.' .Using analyses from previous
chapters and various examples, the remainder of this chapter will
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explain how the planning framework outlined above can accommodate
carrying capacity ideas and analyses.
Identification of Driving Forces
One of the local planner's most important tasks is to identify the events
and decisions that will have serious and extensive impacts in the area of
his planning jurisdiction. These events and decisions may have already
occurred, are occurring now, or are likely to occur in the future. They
might occur locally, or even elsewhere in the state or nation. Examples
of such driving forces are the location of basic and important service
industries, federal revenue sharing, the location of interstate highways
and other transportation facilities, changes in population and demo-
graphic make-up, policies affecting water and energy supplies, the
installation of federal facilities, state and federal supreme court
decisions affecting methods of financing public services, and so on.
Acknowledging that such driving forces can occur in various combi-
nations and in various ways, it is useful to describe alternative futures
for the planning area. One future might describe a maximal growth
situation; another a minimal growth situation. The most probable
future--the one derived from describing the most probable mix of the
most probable driving forces—would usually describe a future inter-
mediate between these two extremes. A useful methodology for
identifying driving forces and organizing them under alternative futures
has been developed by Kane (1972).
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The identification of driving forces necessitates full and effective
communication among representatives from industry, government,
and other segments of the local community as well as communication
between local leaders and officials in state and federal government.
Once the planner has characterized in alternative future scenarios
the forces that will likely result in extensive changes in his city or
county, he is faced with the tasks of developing an analytical frame-
work for analyzing and evaluating the effects of such change and
channeling it in directions that will protect and benefit the community
at large.
Inventory of Existing Resources
In order to examine how driving forces will affect changes in a com-
munity's natural and human resource base, it is necessary, first, to
survey and inventory existing conditions and to determine the state of
the community's existing resources. For accomplishing this inventory,
a resource classification such as that presented in Chapter II is
suggested:
Ambient resources: air, water, open space, quiet and
noise zones, sunlight exposure
Spatial resources: underground space, available and
transitional surface space, airways
space
Infrastructure and transportation, water and water
distributive resources: distribution, wastewater collection,
energy (electricity and gas) distri-
bution, communications
Ecological resources: green plants, nongreen plants,
animals
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Socio-cultural educational and cultural facilities,
resources: health services, security services
(fire, police), recreation services,
housing stocks
Economic resources: raw materials for production inputs,
capital, labor
Amenity resources: seashores, scenic areas, contiguous
natural areas (mountains, deserts,
lakes), open space
Table 4 indicates some of the kinds of questions that need to be asked
and how the inventory might be organized for renewable or flow re-
sources. Table 5 provides a similar organization for nonrenewable or
stock resources. A more complete inventory would and should involve
assessing the qualitative states of existing resources.
Assessment of Changes in the Resource
Base Under Alternative Futures
The last chapter discussed methodologies and analytical procedures
that might be employed in identifying or predicting the effects of certain
driving forces. There are various ways of organizing and classifying
such effects, of course. One mode of organization might involve con-
sidering how the entries in a resource inventory, such as Tables 4 and
5, would change. Additionally, the planner might want to aggregate
changed entries or parameters in the inventory table to assess changes
in such higher order indices as "air quality," "unemployment rate,"
"crime rate, " and even "quality of life" and "environmental quality. "
(See the previous chapter for a more complete discussion of how the
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Table 4. RENEWABLE OR FLOW RESOURCES
(JO
O
Resource
Ambient
air
water
open space
quiet and
noise zones
sunlight
exposure
Transformation
and Distributive
transportation
water and water
distribution
wastewater
collection
energy, distribution
communications
etc.
Ecological
green plants
animals
etc.
Socio-Cultural
educational facilities
health services
security services
etc.
Economic
capital
labor
etc.
Unit Cost
of Use or
Procurement
Regional Net
Annual Use
of
Procurement
Cost
Total Dollar
Amounts
Imported
all colu
Exported
mns should
Distribution
Time
be est
Space
imated
Regional Ownership (%)
Private
for each resource classification
and quality type
Public
Fed.
State
Local
-------
Table 5. NONRENEWABLE OR STOCK RESOURCES
Resource
Spatial
underground
airways
transitional
etc.
Economic
raw materials
for production
etc.
Amenity
seashores
scenic areas
open space
etc.
Unit Cost
of Use or
Procurement
Regional Net
Annual Use
of
Procurement
Cost
Total Dollar
Amounts
Imported
Export
all
est
clai
Estimated
Life
Potential
columns t
mated foz
jsification
Estimated
Annual
Depletion
Rate
hould be
Distribution
Time
each resource
and quality type
Space
Regional Ownership (%)
Private
Public
Fed.
State
Local
-------
construction of indices might be used to measure various kinds of
social, economic, and environmental change. )
Ultimately, the way impact information is or should be organized
depends on the use to which this information is used for policy- and
decision-making purposes. In this context, four general areas of
human-oriented carrying capacity have been identified: 1) The capacity
of the resource base to supply production demands, 2) the capacity of
production to supply the demands for goods and services, 3) the capacity
of infrastructure to distribute goods and services and the materials
used in the production of goods and services efficiently, and 4) the
capacity of the natural environment to assimilate wastes and residuals
resulting from production and consumption. These dimensions or
areas of carrying capacity are, of course, highly interactive. Attempts
to assign carrying capacity limits or ranges must be based on a rec-
ognition that deficient capacity in one area affects carrying capacity in
the others. If a planner has the staff and facilities or can call upon
the requisite expertise, he will be able to analyze the carrying capacity
of systems along the lines suggested in the last chapter. Often, however,
limited budgets and manpower will necessitate a less systematic and
comprehensive analysis of carrying capacity conditions and limits. The
following problems and case studies are offered as examples of how
carrying capacity analyses might be conducted when planning resources
are limited. Each of these examples identify driving forces and suggest
the kinds of effects that need to be taken into consideration.
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Atlantic Coast Brown-Outs--
Recently, heavy demands for electrical energy on the Northeastern
Atlantic Seaboard have exceeded the generating capacity of the system.
This stress on the system beyond its capability to produce or supply
electrical energy has resulted in some brown-outs and threats of others.
Viewing this as a carrying capacity problem, a number of questions
in regional planning arise as to what should be appropriate responses:
Should generating capacity be expanded, and if so, how much? What
would be the effect of an expansion on other supportive resources,
e. g. , fuel for steam electric plants, effects of waste heat disposal on
water bodies, effects of particulate matter in the air? What effect would
expansion have on growth in the region? What policies could be imple-
mented to reduce energy demand by consumers? What would be the
impact of such policies?
Water Importation to Salt Lake Valley--
Water supplies available for municipal, industrial, and agricultural use
in the Salt Lake Valley are limited to presently developed surface and
groundwater sources. The availability of these present supplies
imposes a limit on the levels of water uses that can be sustained. Part
of the Central Utah Water Development Project proposes to import
additional water supplies into the Salt Lake Valley. The accomplish-
ment of such a proposal will effectively increase the carrying capacity
of available water supplies to support activities. To do so, however,
*• •
raises a number of other carrying capacity related issues: What will
be the impact of increased activity on the carrying capacity of other
resources, e. g., wastewater disposal and assimilative capacities,
air pollution, availability of land and land quality? What impetus
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will there be for additional growth, and with what impact on other
supportive resources and infrastructure?
Urban Center Expansion--
The Ogden Valley, situated 5 miles east of Ogden, Utah, is basically
a rural agricultural valley of roughly 50 square miles with a total
population of about one thousand residing in three small communities.
It is reached via a winding two-lane road through the short and scenic
Ogden Canyon. The canyon itself is an important recreation resource
offering excellent fishing and camping by the river which flows from
the valley watershed and the Pine View Reservoir. The Ogden Valley
offers extensive recreation opportunities for residents of the urbanized
Ogden and Salt Lake City regions. The reservoir is a major water-
based recreational area offering swimming, boating, and fishing. In
addition, golfing, picnicking, and camping facilities have been developed
in the valley, and two major ski areas on the mountain slopes serve
the winter recreationists. Upland and mountain wildlife species abound
in the valley and the surrounding mountain forest areas. Presently,
there are a number of proposals for large developments in the area
ranging from vacation resorts to condominiums to lower density summer
home developments to housing tract developments for bedroom com-
munities for the urban areas. The Highway Department is considering
plans for major improvements in access to the valley. In the face of
the mounting pressure for development and the serious and irreversible
environmental demage which could result, a comprehensive analysis of
the carrying capacity of the Ogden Valley is greatly needed. Some of
the carrying capacity related issues and questions are: What is the
capacity of the reservoir and the river downstream to maintain the
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natural water quality levels and continue to support existing ecosystems?
What is the capacity of soil to resist erosion from intensive recreation
or development use? What.is the capacity of the valley to provide infra-
structure for development—water supplies, wastewater disposal, solid
waste disposal areas? What capacity constraints are imposed by the
existing transportation system? What will be the effects of the proposed
high speed access? What will be the impact of air quality conditions with
increased traffic along with housing and commerical developments?
What plant and animal species will be displaced, and what will be the
capacity of ecological systems to absorb changes from development?
What is the capacity of the valley to serve as an open space and recre-
ation resource?
Recreation Development in Water sheds--
The canyons immediately above Salt Lake City are being subjected to
intense pressure for development. These canyon watersheds supply
most of the water needs for the Salt Lake Valley. They also provide an
outstanding recreational resource for winter skiing and summer moun-
tain outings and vacations. Large resorts have already developed in
the canyons to serve recreation interests with many new resort hotel
and private summer home developments proposed. Again, questions
relating growth and carrying capacity arise: What is the capacity of
the fragile watershed ecosystems to support various intensities of
development and recreation use? What is the capacity of air and water
resource systems to absorb the pollutants from these developments?
Can a transportation system of adequate capacity be constructed with-
out complete disruption of the canyon ecosystem? What user-capacity
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can the recreational areas accommodate and still provide satisfactory
recreational experiences?
The foregoing case examples underscore the highly interactive character
of the four dimensions of carrying capacity. Again, the four general
areas in which the carrying capacity of a populated region might fail
are: (1) Supply/demand for resources in the production of goods and
services, (2) supply/demand for goods and services by consumers,
(3) efficiency of distributive resources/distribution requirements, and
(4) assimilative capacity of the receiving environment/levels of wastes
and residuals generated from production and consumption. Five ad-
ditional examples are provided below to clarify further some of the
issues involved in (3) and (4). The first three cases deal with (3); the
latter two deal with (4). In these more specific cases, it should be
noted the carrying capacity dimensions are still highly interactive
although a more narrow examination of the carrying capacity aspects
of the problem is undertaken for illustrative purposes.
Urban Freeway Congestion--
Rush hour freeway congestion of urban regions may be cited as an
example of carrying capacity in terms of an infrastructure or service
delivery system. The freeway has a given capacity relative to the
maximum volume of flow in a given period of time. When vehicles
overload the system, volume drops off as traffic congestion creates
stoppages and delays which tend to reduce flows to zero. In terms of
the regional capacity to provide transportation services, some of the
issues are: How much freeway capacity can be provided without in-
fringing on quality levels of other air, land, and water related
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resources? How will expansion of freeway transportation capacity
affect the expansion of other urban activities with their subsequent
effects? What would be the impact of measures to limit freeway usage
at capacity levels for the present system?
Treatment Plant Capacity--
In counties surrounding urban areas (Washington, D. C., for example),
continued expansion of residential and commercial development into the
urban fringe has placed heavy burdens on existing wastewater treat-
ment and disposal facilities already operating at capacity. In such
instances, no additional sewer hookups can be allowed without over-
loading the system and causing pollutants to enter nearby streams and
rivers. Here, again, the capacity of existing infrastructure along
with enforcement of standards on effluent discharges acts as a carrying
capacity constraint on the region. In this situation some relevant
questions are: What will be the effects on growth of providing additional
waste disposal capacity? How will removal of this capacity constraint
affect other aspects of environmental quality in the region such as open
space, pressure on recreation and other cultural resources, and
delivery systems for other social services? What will be the impact
of a moratorium on additional building permits or maintaining current
waste disposal capacities?
Recreational Re sources--
Recreation resources of the nation have been under mounting pressure
over the past several years. Of particular concern are areas of unique
natural and scenic beauty such as the national parks. In Yosemite for
example, the large number of visitors traveling through the park in
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vehicles caused serious congestion, air quality problems, and a reduc-
tion in the overall quality of experience for the park visitors. Some
of the carrying capacity questions which perhaps were considered in
adopting new rules for park visitations were: What number of visitors
could the park accommodate and still provide a desired level of quality
experience for the recreator? Can number of visitors be increased
or must they be reduced? What programs should be implemented to
effect appropriate changes in numbers? How should the number of
visitors be accommodated without endangering the resource itself?
Wastewater Disposal and Water Pollution--
Pollution of rivers and lakes by the disposal of heavy waste loads in
these receiving waters has become a common problem across the
country. Where the ability of the water resource to assimilate these
waste loads has been exceeded, there has been attendant destruction
of the aquatic ecosystem, as well as decreases in the potential for
water use in other activities. In two cases in the Northwest, polluted
waters were upgraded to near their natural quality levels. Lake
Washington in Seattle was being heavily polluted by wastes from resi-
dential and commercial development which had grown up around it
over the years. However, reduction of the pollution load through
comprehensive wastewater management has allowed the lake to re-
generate to quality levels that will again permit swimming and recre-
ational use. The Willamette River in Oregon, highly polluted by pulp
mill and other industrial wastes, has also been cleaned up to the point
where anadromous fish runs are again.being reestablished. The capac-
ity of water to assimilate wastes and residuals depends on the enforce-
ment of water quality standards. Some of the carrying capacity ,
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questions with respect to determining these standards are: What other
uses are intended for waters which will be affected by setting of certain
standards? What economic, environmental and social costs and trade
offs are involved in maintaining high quality levels in a water body as
opposed merely to using it as a waste carrier?
Air Pollution and Emissions Control--
Excesses in the use of air sheds to assimilate emissions has also be-
come a pervasive problem. The ability of the air to assimilate such
emissions is, of course, dependent on the meteorological conditions
prevailing over a given time. The loading function, however, is
related to the activities and processes going on within the region as
well as to the enforcement of quality standards. Controls to maintain
those standards, applied to the activities or sources of emissions,
bring up some of the following carrying capacity questions: How will
emission controls to maintain air quality levels affect other activity
levels, such as transportation and industrial production? What will
be the regional impact of reducing levels of these activities to satisfy
emission standards? How will the substitution of other activities or
technological controls affect carrying capacity? What are the social,
economic, and environmental costs of maintaining specified standards?
In summary, virtually every urban center is faced with problems of
accommodating some degree of future development. In managing the
environment for quality regional growth, questions related to the
carrying capacity of environmental resources lie at the heart of the
problem. These short examples provide only a broad glimpse of the
issues which overlay a myriad of technical questions about the ability
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of resources to accommodate growth without precipitous declines in
environmental quality of the particular area and other contiguous areas
which draw upon it for basic "resource support. The carrying capacity
concept implies viewing the regional environment as a support system
for numerous, interdependent and competing activities and systems,
and determining the limiting conditions and capabilities of the regional
environment to absorb, withstand, support or sustain these activities
without downward trends or unacceptable changes in quality levels.
Formulation of Alternatives
Once driving forces have been identified and the range of their impacts
estimated, the planner is faced with the task of formulating alternative
ways of coping with change and channeling it in safe and beneficial
directions. In doing so, he should ask the kinds of carrying capacity
questions that were asked in the series of examples in the last section.
Alternatives that would threaten to seriously diminish the carrying
capacity of key support systems in the community should, of course,
be ruled out of any further consideration.
Evaluation of Trade Offs
The next step is that of evaluating proposals and competing management
alternatives. The merit of any community or society, or of any insti-
tution, policy, or program within that society, must be judged finally
by its effectiveness in providing a good life for its members. It is,
of course, a difficult and challenging task to define "the good life" and
cognates such as "quality of life. " Equally difficult is the task of
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measuring the progress that programs and policies might be making
toward the establishment and maintenance of "quality life. " These
problems were discussed in Chapter V and will not be reexamined.
Suffice it to say here that there are a multiplicity of elements making
up "quality life" and that any policy or program will involve promoting
or safeguarding certain of these elements while sacrificing or jeopar-
dizing others. Every action involves value trade offs. The evaluation
stage in planning involves identifying the range of trade offs involved
in and among alternative courses of action, determining the relative
importance of values involved in these trade offs, and choosing the
trade off mix that most nearly satisfies one's decision principle (e. g.,
maximizing positive values or minimizing negative values).
Before turning to a fuller treatment of implementation problems, one
further comment needs to be made about carrying capacity as a value to
be reckoned with in the evaluation process. When production demands
exceed requisite resource inputs; or the demand for essential goods and
services cannot be met by a community's productive capability; or con-
gestion and inefficiency in a community's infrastructure and distributive
resources result in frequent and recurring blockages, stops, and delays;
or the atmosphere and terrestrial and aquatic environments cannot
assimilate wastes and quality levels in these media cannot be maintained
at aafe and tolerable levels--when carrying capacities such as these
are exceeded, society as a whole suffers. Zones of safe carrying
capacity are essential to the efficient functioning of a community and
to the achievement of personal and social values. In this fundamental
way, carrying capacity is an important extrinsic value and one the
planner cannot afford to ignore.
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Implementation
Once strategies for managing change in society have been evaluated and
selected, effective means must be found for implementing these strat-
egies in an established and on-going institutional and social setting.
This section will address the problem of implementation by focusing
on three critical areas in which carrying capacity controls might be
exercised: Population, economic activity, and land use.
Human Population--
The human population variable has been considered in many carrying
capacity studies as perhaps the most important variable. If the human
population is too high then a portion of this population should be de-
creased; if the population is too low then population increase can be
allowed or stimulated. Of the three factors important for population
change--fertility, mortality, and migration--only migration effects
any very rapid changes in population. There are important differences
in birth and death rates, of course, but these are more determined by
differences in the age level of specific populations than by anything else.
Older populations have high deatih rates and young populations have high
overall birth rates. Differences in fertility were once considerable,
but the differences have become much smaller in the most recent
decades. Also, there appears to be very little difference among areas
in the United States in overall mortality. Therefore, it is migration
that has the most startling effects on the population of an area. Lee
et al. (1971), for example, found that more than 70 percent of the
persons entering adulthood during the 1950 to I960 decade left some
mid-we stern rural counties. They found instances where the median
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age in a county rose ten years in just a single decade because of the out
migration of the younger population.
With this great potential for the change in the population of an area, it
would appear desirable on the surface to devise some means to effect
population changes very quickly in a given region. In reality, however,
population change is not particularly amenable to manipulation by the
political sector of the nation. In fact, our traditional means of handling
population change has been to maintain a laissez-faire attitude by
government. The federal courts have not allowed states or their sub-
divisions to control the movement of persons within the United States.
This constitutional doctrine was tested early in the history of the Union
when in 1865 the Legislature of the State of Nevada enacted a statute
that levied a tax of one dollar upon every person leaving the state.
No doubt the legislators of Nevada wished to discourage out migration.
In 1868 the case of Crandall vs. Nevada reached the Supreme Court
of the United States and the Nevada statute was declared unconstitutional
(6 Wall. 35-1968). Mr. Justice Miller in writing the majority opinion
for the court indicated that every citizen in the United States has the
right to travel to the seat of government, unrestricted, or to otherwise
have free access to ports, land office or other offices operated by the
national government.
Further elaboration on the right of the free movement of persons within
the United States is found in the case of Edwards vs. California which
came before the Supreme Court of the United States in 1941 (314 United
States 160-1941). This case came about because the Legislature of the
State of California had, during the great depression, passed a law which
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prohibited the transporting of indigent persons into the state. Mr.
Justice Byrnes in delivering the opinion of the court used very strong
language to strike down this California statute. He pointed out that
although the states did have constitutionally mandated police power
(the power to protect the health, welfare, and morals of the community)
this did not mean that there were no boundaries to a state's legislative
activity in this area. He indicated that no state could gain a momentary
respite from the pressure of events by the simple expedient of shutting
its gates to the outside world. Generally speaking, it appears that any
attempt by a state or its subdivision to overtly limit migration would
be held unconstitutional by the Supreme Court of the United States.
This is not to say that the national government, or even state govern-
ments, has been without policies that affected migration in the past.
Policies exist even if they are not well articulated. An example of a
population policy can be found in the law that permitted homesteading
in the American West. In this case the national government essentially
gave 160 acres of land to any person who would live on that land for a
specified period of time. With this law in effect the vast spaces o the
West filled up between the period of the Civil War and the turn of the
century. Another example of a population policy can be seen in the
National Housing Act of 1937 and its subsequent amendments. This act
established the Federal Housing Administration system of mortgage
insurance thereby allowing the middle class of the United States to
construct new housing and to move in such great numbers into the
suburbs after World War II. A third example is the interstate highway
system which consists of super highways going away from or into cities,
depending on your viewpoint, which have allowed Americans to live
144
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long distances away from their work and still commute by automobile
in comfortable fashion to and from their place of work. These latter
two policies have contributed to the depopulation of our major American
cities and the building of a whole new urban form--the urban sprawl.
Economic Development--
Economic development as discussed here is viewed very narrowly as
the investment of capital or movement of wealth into an area. Migration
appears to be closely related to economic development, and under many
circumstances it is directly induced by economic development. Mi-
gration is clearly influenced by the business cycle, with higher immi-
gration rates seen into areas with a prosperous economy and lower
immigration, or even out migration seen in the less prosperous areas.
This explains the high influx of the southern rural poor into the more
affluent northern metropolitan counties in the period 1945 to 1970
(Bowles et al., 1969; Gallaway, I960). Much of this migration, of
course, was tied to the disappearance of employment opportunities
in the rural areas as agriculture was rapidly mechanized during this
period. An example of this can be seen in the data shown in Table 6.
As Utah's per capita income fell relative to the average United States
per capita income in the 1960's, considerable out migration occurred.
Also, note that as the relative income of Utah residents rose at the
beginning of the decade and in the early 1970's, in migration was
experienced. In the decade 1960-1970, the state population increased
by 18. 9 percent, but this was entirely due to the excess of births
over deaths because the net loss due to migration was 1. 2 percent
(Hiibner, 1973).
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Table 6. UTAH PER CAPITA INCOME AND
NET MIGRATION 1960-1972
Year
I960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
Utah as a
Percent of U.S.
(per capita income )a
89.1
90.2
91.4
90.2
87.8
85.9
83.6
82.8
81.9
80.3
81.9
82.8
83.0
Utah Economic and Business Review, Vol.
1973).
Utah Economic and Business Review, Vol.
Estimated Net
Migration
(percent)"
9-8
15.4
1.8
-3. 1
-13.9
-3.5
2.3
-6. 1
-6.4
1. 1
0.3
8.9
12.7
33, No. 10 (Oct.,
33, No. 5 (May,
1973).
Land Use and Land Use Planning--
The concept of land use planning is relatively new in the United States.
Historically, the individual property owner was free to use his prop-
erty as he wished, but this has changed drastically since 1928 when
zoning was sanctioned as within the permissible "police power" of the
states (Euclid vs. Ambler Realty Company, 272 United States 365).
Now almost every unit of government regulates, in some way, the use
of land and has the means to implement land use plans. This is not to
146
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say that land use planning or its means of enforcement, zoning laws,
are always wisely used or not abused. Large tracts of land surrounding
American cities have been "planned" for use as estates with two or
more acre lots containing only single family dwellings, and as lots of
this size cost in excess of $10, 000 per lot, it has become impossible
for a low income family to move into these areas. Most likely the
worst excesses of this type of "planning" will soon be gone, but they
appear quite bothersome at the present time.
Several positive benefits have been achieved through land use planning,
such as protection from housing and industrial encroachment on areas
important to water recharge, wildlife production, high value agriculture
production, or historical preservation. Population density can also be
controlled. Through effective land use planning and zoning, industrial
pollution of air sheds and watersheds can be prevented by planning for
industrial developments in areas where the least harm may be done.
The location of urban infrastructure (utilities, roads, and public
facilities) can be programmed in advance so that inconvenience to the
newly developed areas can be minimized and land acquisition costs
made lower. With the location of industrial areas, airports, etc.,
known in advance, housing development can be located so as to be
compatible with this development.
Finally, all development can be kept out of some areas--if that is
desirable for the purpose of maximizing agricultural production,
preserving scenic values and so on. The appropriation of the potential
benefits from land use planning are keyed to an understanding of the
147
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capacities of the land and related resource base as a basis for deter-
mining appropriate types and levels of uses.
Summary of Control Measures Available
to Political Units--
A -wide variety of political institutions are available within the United
States to implement the above carrying capacity controls described
for the three social growth sectors. These are listed in Table 7 with
an indication as to whether or not the particular political unit can
effectively implement the control. In the political institutions struc-
tured by the United States Constitution in setting up a federal system,
powers are largely shared by the two primary levels--state and
national. Many powers are exercised by both levels, but some are
reserved to the states, e. g. , the police powers, and some are delegated
exclusively to the national government. An example of this appears in
Table 7 as indicated under population (migration) control. The power
over interstate commerce was delegated exclusively to the national
government by the constitution. Consequently, this important mech-
anism of control over migration is not available to the states or their
subdivisions. Local governments (counties, townships, and munici-
palities) are creations of the states and share such powers as they are
given to them by the states.
The most pervasive control mechanism in the areas discussed appears
to be that of economic development. As all of these political structures
can either choose to spend or not to spend funds for public facilities,
they have some control over economic development and thereby affecting
the growth of a given area. It should be noted that the definition of
148
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Table 7. CONTROL MECHANISM AVAILABLE TO
POLITICAL INSTITUTIONS
Political Institutions
Federal Government
Federal Agency with regional
impact or mission
Federal Corporation
Interstate Compacta
State Government
Interstate Compact3-
State Corporation
Multi- County District
County
County Corporation
Special District
Township
Municipality
Municipal Corporations
Municipal District
Control Mechanism Available
Population
X
Economic
Development
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Land Use
Planning
X
X
?
X
X
X
?
X
X
?
X
X
X
9
X
The interstate compact being created by both the State and
Federal levels, working together, appears under both categories here.
public facilities can be quite broad. A political unit can build a factory
to produce a public good, develop energy sources to run the factory,
and then sell all of this as surplus property to a private concern at a
fraction of its replacement value if it becomes public policy to do so.
Public policy, in a democracy, is set by elected officials. Consequently,
the decision as to whether to intervene in the "natural system" is
political. What should be done by wise men and what can be done by
149
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prudent office holders who wish to remain in office do not always pre-
sent the same outcome. The decision to tax, spend, borrow or to
print money, as part of a regional economic policy, is laced with the
politics of partisanship, ideology, and selfish interest. One way to
alleviate some of the trauma associated with the politics of decision
making is to take the decision out of the political arena. Routine
decisions are handled by a reasonably nonpartisan career bureaucracy.
Another method is to organize a government corporation for a specific
purpose. These corporations, similar to those of the private sector,
are simply totally owned entities of a government. Successful examples
of these include the Tennessee Valley Authority on the federal level;
and state or municipal housing corporation, turnpike or bridge authorities
on the nonfederal level. These political entities operate quite inde-
pendent of the political units of government, because they do not have
to request funds for their operation. They sell their services or produce
goods that generate operating revenue, but do not possess the taxing
power. They appear to be potent forces for economic development and
growth as has been shown by the successful example of TVA. Their
success in using land use planning, however, is not clear at the present
time.
The list of available and diverse political units in Table 7 suggests a
number of possibilities for implementing a strategy for controls related
to the carrying capacity concept. All units have power available to
influence economic development. This variable, in return, can affect
population levels and land use planning activities.
150
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If the region of concern for carrying capacity is geographically small,
one of the smaller units of government might be used. If there appears
to be some structural or political reason why this is not possible, the
next larger unit (geographically) could be utilized. Political boundaries
should not be a concern in implementing control mechanisms. Other
political structures should be able to substitute if larger areas are
needed.
CARRYING CAPACITY: TWO EXAMPLES
OF REGIONAL PLANNING RESPONSE
In the face of the kinds of problems previously noted, a few regional
planning groups have responded with studies of optimum growth and
regional carrying capacity. As additional background to placing car-
rying capacity within the regional planning process, it is interesting
to note the direction and experience of these studies.
Optimum Growth; Metropolitan
Washington, D. C.
"Optimum growth: Consequences for the year 2000 in metropolitan
Washington" acknowledges that there has been a breakdown of the
previously held attitude regarding growth and development of com-
munities, but that the growth ethic has not been pervasively replaced
by any alternative. The report notes that planning and decision-making
systems are now expected to actively promote environmental quality as
a goal to be achieved rather than simply seeking to mitigate adverse
environmental effects of development. This change in community
151
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attitude has brought into question the extensive use of "demand pro-
jection" by comprehensive planning approaches. Better methods are
therefore needed in constructing and operationalizing regional planning
systems. The concept proposed is the use of "optimum growth" and
"balanced communities" as a focal point in the planning process to
examine trade offs. Trying to define these terms from the standpoint
of real-world, community-he Id values becomes complex and "quanti-
tatively elusive. " However, they do introduce a set of useful trade
offs to be examined. The following are listed: 1) Diversity versus
homogeneity, 2) change versus stability, and 3) community self-
sufficiency versus economic basis for specialized services and
p
institutions.
Recognizing the importance of techniques or strategies for implementing
optimum growth plans, the report notes that policy level subscription to
the concept of optimum growth is insufficient to implement it. Hence,
planners need to focus on controlling the "drivers" of population and
economic growth, and the impacts of growth. In most cases, current
strategies for controlling growth are aimed at controlling the impacts
of growth rather than the driving forces behind growth.
A planning and decision process useful for the implementation of a
regional plan is sketched which recommends a communication format
to overcome the limitations and frustrations imposed upon elected
officials by differing perspectives of discussion and limited available
time. The communications format emphasizes problem definition,
structuring of the discussions of alternative solutions, identification
of constraints, resolution of conflicts, and assignment of responsibility
152
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for action plans. These activities are carried out by representatives
of the various governments in the region. Recognition of constraints
and budget capacities plays an important role in the communications
format. The three major constraints (or budgets) faced by planners
are: 1) Natural resources budgets, or limitations imposed by the
natural environment in terms of the holding capacity or carrying capac-
ity in relation to such things as air or water quality standards; 2)
physical budgets, a need for significant feedback between carrying
capacity and the required public and private expenditures in applying
the discussion format; and 3) community response budget, or the non-
monetary concerns such as overcrowding, clean air and water, the
desire to preserve community character, etc., which are perceived
by members of the community.
A number of possible regional roles that would have to be filled in
order to ope rationalize the proposed discussions and planning pro-
cedures are also outlined. Among these are (1) technical assistance
for creating models of budget capacity, using budgets to determine
when jurisdictions are approaching their carrying capacities and
improving communications, (2) a forum for setting agendas for
communication and developing roles for responsible parties, (3)
regional spokesmen to occupy roles of advocacy of optimum growth
control targets, (4) regional resource managers to identify the most
efficient locations for growth, based on principles of resource linkage
and regional specialization, and (5) control structures to link planning
and implementation.
153
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The work stress that "optimum growth" and "balanced communities"
require considerable definition, but are useful terms for stimulating
interrogative thinking about planning alternatives. Also, since our
urban areas are very complex, the concept of optimum growth is best
derived from a process and should not be stated merely as a goal.
Further emphasized is the fact that control of variables that multiply
downstream consequences (i. e. , the drivers of economic and population
growth) is preferable to controlling variables which are simply related
to the impacts of growth. Regional coordination in terms of regional
resource managers and regional spokesmen is required for the suc-
cessful use of the optimum growth concept in regional management.
Ecology and the Economy;
The Pacific Northwest
The Pacific Northwest River Basin Commission Urban and Rural
Related Lands Committee has recently undertaken a study attempting
to determine the extent to which a high-quality environment can be
maintained in the face of population and economic growth in the Pacific
Northwest. The study adopts a carrying capacity or sustained yield
approach to assess the capabilities of the resources of the area to
indefinitely sustain various levels of population, economic activity,
and degrees of protection of natural and intangible values.
The carrying capacity approach outlined in the study was developed by
using available data and best judgments to (1) describe an optimum
environment for the average individual in terms of available goods,
services, and intangibles, and (2) identify alternative long-range goals
154
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for the Pacific Northwest in terms of population levels, economic
activity, and degree of protection of less tangible values, and (3)
compare various combinations of the elements of (2) with the require-
ments for the "optimum" quality of life defined under (1). The descrip-
tion of an optimum environment or an optimum "quality of life" was
obtained basically through an examination of Maslow's (1954) concept
of a five-level hierarchy of human values. In brief, Maslow contends
that human experience is needs-organized and that human needs are
arranged in a hierarchy such that when lower level needs have been
satisfied, higher level needs emerge and come into play. Maslow
argues that the human being can live a quality life only when each level
of human needs has been properly satisfied. The five levels of human
needs identified by Maslow in the order that they emerge are (1) physio-
logical needs such as food, shelter, clothing, sleep, etc., (2) security
needs such as protection from physical harm and the assurance of a
continuing income and employment, (3) social needs such as acceptance
by other people, (4) ego needs such as the achievement of independence,
self-esteem, recognition, etc., and (5) self-fulfillment needs such as
achieving a sense of accomplishment and capability, and acceptance of
new challenges.
The attainment of an optimum quality of life, i. e., the fulfillment of
each level of human needs in the proper order, requires a substantial
level of production of goods and services. When the mean per capita
income exceeds the amount necessary to satisfy the most basic needs,
the other higher level needs (which are generally more intangible) then
become important. The point is that in order to achieve an optimum
environment, every individual must have some minimum income.
155
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The study defines the relationship between population and industry
through use of the concept of "servant machine. " The concept is applied
to estimate amounts of use and consumption of resources and potential
pollution and other environmental impacts caused by population and by
industrial and other economic activity. On the average, one individual
can produce $250 per year in goods and services. This figure divided
into the per capita GNP of the average citizen of the United States
($3, 490 in 1967 doUars) indicated that each individual has the use of 13
"servant machines. " The assumption is that each machine would have
an impact on the environment equal to that of its owner.
The capacity of a region to sustain population in industry is determined
in a three-step process. First, optimum per capita income levels are
calculated as a function of the description of the optimum quality of
life decided upon. Second, annual capacity for indefinitely sustained
productivity is projected for each of seven categories of industrial
activity (commercial forest land, agricultural land, commercial
fishery, recreation and tourism, location-based industry, and mining
and minerals) and a total potential GRP is calculated from these esti-
mates. Finally, the carrying capacity of the region is calculated by
dividing the total potential GRP by the per capita share of GRP dictated
by the optimum per capita income as defined under step one. Calculated
in this way, carrying capacity has units of numbers of people, and
assumes 100 percent recycling and pollution control. Lower levels of
recycling and pollution control require that GRP be lower, thus low-
ering the carrying capacity for a given optimum per capita income.
156
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SUMMARY
This chapter has discussed ways of incorporating carrying capacity
considerations in a planning process that involves analyzing and
evaluating alternative ways of constructively dealing with critical
areas of change and development. In the briefest terms, a carrying
capacity-based planning process involves examining how driving forces
(events and decisions that occasion significant change) will affect the
capacity of the resource base (water supply, labor, capital, raw
materials, etc. ) to support production activities; the capacity of
these production activities to supply essential goods and services;
the capacity of infrastructure resources (waterways, roads, trans-
mission lines, sewerage, etc. ) to distribute materials and goods and
services without paralyzing congestion; and the capacity of the environ-
mental media (air, water, land) to assimilate the wastes generated
from production and consumption. The information conveyed by
carrying capacities indices--measurements that indicate how near
actual capacities are to limits or bounds--need to be carefully con-
sidered by regional planners and given due weight in the evaluation of
programs and policies designed for the wise management of change.
157
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SECTION IX
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SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
1, Report No.
3. Accession No
w
4. Title
Carrying Capacity in Regional Environmental Management
7. Authors) A. B. Bishop, H. H. Fuller ton, A. B. Craw-
ford, M. D. Chambers, and M. McKee
g. Organization
Utah State University
Logan, Utah
S. Report D
,6.
8. Pefforaaag Oigaajzaiioa
Re port No.
10. Project No.
11. Contract/Grant No.
802444
"if"' Type ofReport and
_j Period Covered
Envlronj^ntal Profession Agency
Fina
ort
15. Supplementary Notes
Environmental Protection Agency report
number, EPA-600/5-7U-021, February
16. Abstract lnis report examines the concept of carrying capacity in the con
text of regional environmental management. Historically, the notion of
carrying capacity developed out of descriptions of the growth § dynamics
of natural populations, and as such has been used as basis for range §
forest management practices. Applied to human activities, however, the con
cept must be broadened to include the complex relations among resources,
infrastructure and productive activities, residuals, and societal prefer-
ences for quality of life within both the natural § human environments.
Four dimensions of a human oriented carrying capacity--resource/production
environment/residuals, infrastructure/congestion, § production/societal re
lations--are described within normative § operational definitions of car-
rying capacity. Carrying capacity is then viewed from the standpoint of re
sources, regional structure, § regional models to see how it fits within
the theoretical (J analytical considerations related to these7 areas. A car
rying capacity-based planning process is described where the forces for
change in the region are analyzed in terms of impacts on identified carry-
ing capacity indices § compared with desired levels to pinpoint areas in
which capacities have been exceeded. Consideration in applying carrying
capacity concepts in local/urban planning are discussed.
17a. Descriptors
Carrying Capacity; Regional Model; Input-Output Models; Simulation
Models; Externality Models; Regional Environmental Management
17b. Identifiers
17c. COWRR Field & Group
IS. Availability
Abstractor
Send To:
WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON. D. C. 2O24O
Institution .
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