EPA-600/2-76-237
October 1976
Environmental Protection Technology Series
CONTROL OF SEDIMENTS, NUTRIENTS, AND
ADSORBED BIOCIDES IN
SURFACE IRRIGATION RETURN FLOWS
Robert S. Kerr Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Ada, Oklahoma 74820
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface 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 ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to develop and
demonstrate instrumentation, equipment, and methodology to repair or prevent
environmental degradation from point and non-point sources of pollution. This
work provides the new or improved technology required for the control and
treatment of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-76-237
October 1976
CONTROL OF SEDIMENTS, NUTRIENTS, AND ADSORBED
BIOCIDES IN SURFACE IRRIGATION RETURN FLOWS
by
David L. Carter
James A. Bondurant
U.S. Department of Agriculture
Agricultural Research Service
Western Region
Snake River Conservation Research Center
Kimberly, Idaho 83341
Interagency Project No. EPA-IAG-D5-F648
Project Officer
Arthur G. Hornsby
Source Management Branch
Robert S. Kerr Environmental Research Laboratory
Ada, Oklahoma 74820
ROBERT S. KERR ENVIRONMENTAL RESEARCH LABORATORY'
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
ADA, OKLAHOMA 74820
-------
DISCLAIMER
This report has been reviewed by the Robert S. Kerr Environmental
Research Laboratory, U.S. Environmental Protection Agency, and approved
for publication. Approval does not signify that the contents necessarily
reflect the views and policies of the U.S. Environmental Protection
Agency, nor does mention of trade names or commercial products constitute
endorsement or recommendation for use.
ii
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ABSTRACT
The technology available for the control of sediments, nutrients, and
adsorbed biocides in surface irrigation return flows has been reviewed
and evaluated. Some of this technology could be applied immediately to
reduce sediment and associated nutrient and biocide concentrations in
surface irrigation return flows. Much of the available information
needs to be integrated to develop improved control practices. New ideas
and new control technology are needed. Economic incentive programs are
needed to improve acceptance of control technology. The factors con-
trolling erosion and subsequent sediment concentrations in surface
irrigation return flows, and how these factors can be managed to reduce
erosion and sediment concentrations are reviewed and discussed. Three
approaches (1) eliminating surface runoff, (2) reducing or eliminating
erosion, and (3) removing sediments and associated nutrients and bio-
cides from surface irrigation return flows, and control measures for
each approach are discussed. Research and demonstration needs for
improving and developing new control technology are presented. These
include simulation modeling of known erosion parameters, the develop-
ment of improved irrigation systems and methods, the design of improved
irrigation water distribution systems, and field management practices.
The need for more information on design and operational criteria for
sediment retention basins is discussed.
This report was submitted in fulfillment of Interagency Agreement
Number EPA-IAG-D5-F648 by the U. S. Department of Agriculture, Agri-
cultural Research Service, under the partial sponsorship of the
Environmental Protection Agency. Work was completed as of April 1976.
iii
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CONTENTS
Sections
I
II
III
IV
VI
VII
VIII
IX
Conclusions 1
Recommendations 3
Introduction 4
Sediments and Adsorbed Nutrients and Biocides in
Surface Irrigation Return Flows
A. Erosion on Irrigated Land 6
B. Sediment in Surface Irrigation Return Flows 10
C. Nutrients in Surface Irrigation Return Flows 15
D. Biocides in Surface Irrigation Return Flows 16
Technology Available for Controlling Sediments and
Associated Nutrients and Biocides in Irrigation
Return Flows 18
A. Eliminating or Reducing Surface Irrigation
Return Flows 18
B. Reducing or Eliminating Erosion 22
1. Controlling Slope 22
2. Controlling Furrow Stream Si2e 24
3. The Run Length 25
4. Controlling Irrigation Frequency and
Duration 27
5. Cultural Practices to Control Erosion 27
C. Removing Sediment and Associated Nutrients
and Biocides from Surface Irrigation Return
Flows 28
1. Controlling Tailwater 28
2. Utilizing Sediment Retention Basins to
Remove Sediments 29
Simulation Techniques for Estimating Sediment and
Associated Nutrient and Biocide Loads in Surface
Return Flows 32
Research and Demonstration Needs 34
Literature Cited 37
Bibliography 40
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FIGURES
No. Page
1 Soil loss rate as a function of eroded cross- 11
sectional area, and furrow-spacing, for a soil
bulk density of 1.20 g/cm .
2 Erosion occurring under surface irrigation on 2 12
percent slope land. These furrows were eroding
at the rate of 100 t/ha (45 tons/a) at the point
shown.
vl
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TABLES
No. Page
1 WATER FLOW AND SOIL LOSS ALONG IRRIGATION FURROWS 7
(Mech and Smith, 1967)
2 SEDIMENT CONCENTRATIONS IN IRRIGATION AND DRAINAGE 13
WATERS FOR TWO LARGE TRACTS DURING THE 1971 IRRI-
GATION SEASON, PPM
3 IDENTIFIED CHLORINATED HYDROCARBON AND THIOPHOSPHATE 17
PESTICIDES DETECTED IN SURFACE DRAIN WATER IN THE
SAN JOAQUIN VALLEY, CALIFORNIA* (Johnson et al.,
1967)
4 TOTAL ANNUAL ENERGY INPUTS, IN THOUSANDS OF KILO- 19
CALORIES (OR GALLONS OF DIESEL FUEL) PER ACRE
IRRIGATED FOR NINE IRRIGATION SYSTEMS, BASED ON
36-IN. (915-mm) NET IRRIGATION REQUIREMENT AND
ZERO PUMPING LIFT (Batty £t al., 1975)
5 DESIGN SUMMARY OF NINE IRRIGATION SYSTEMS (Batty 20
^ al., 1975)
6 SUMMARY OF RECIRCULATING SURFACE IRRIGATION SYSTEMS, 23
SOUTHERN IDAHO 1964-1965 (Bondurant and Willardson,
1965)
7 COMPUTED DISTRIBUTION OF WATER UNDER MULTI-SET AND 26
STANDARD IRRIGATION PRACTICES FOR A 50-mm (2.0 in)
IRRIGATION
vii
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SECTION I
CONCLUSIONS
1. Sediment and adsorbed nutrients and biocides in surface irrigation
return flows originate primarily from furrow erosion on furrow
irrigated land. Some sediment is derived from soil erosion that
occurs with other^ irrigation methods such as improperly used
sprinkle systems and certain flood irrigation practices.
2. The sediment and associated nutrient and biocide concentrations in
surface irrigation return flows depend primarily upon the land
slope in the direction of irrigation, the furrow stream size,
the run length, the condition of the soil surface, the infiltra-
tion rate in relation to the application rate, the duration of the
irrigation, tillage practices, the number of irrigations per season,
the crop, and tailwater management. Sediment concentrations in
surface irrigation return flows vary widely, from 0 to more than
15,000 ppm.
3. The sediment and associated nutrient and biocide concentrations in
surface irrigation return flows could be reduced by applying control
technology developed during the past 40 years. Much of the avail-
able technology needs further development and new technology inte-
grating relationships among soil erosion parameters needs to be
developed.
4. An incentive program for applying erosion and sediment control
practices on irrigated land is needed. This program could be in
the form of low interest loans or cost participation. Acceptance
of new control practices will depend upon economic benefits.
5. Additional technology should be developed on multi-set irrigation
systems, trickle irrigation methods, tillage practices emphasizing
minimum tillage, design and operational criteria for sediment
retention basins, within-row irrigation, tailwater management,
irrigation system design to facilitate water delivery on farmer
demand, simulation models for predicting sediment and associated
nutrient and biocide losses, use of grass buffer strips for
filtering sediments, and land forming and shaping to reduce erosion
and sediment losses.
6. The dissolved nutrient concentrations in surface irrigation return
flow differ little from those in the irrigation water, except
where nutrients are added directly to the water for fertilizing the
crop. Some nutrient enrichment can result from leaching of nutri-
ents from decaying plant residue on the soil surface.
-------
The limited available information indicates that essentially all
biocides in surface irrigation return flows are adsorbed on
sediments except where they are sprayed directly into the water or
washed from plant material into the water by rainfall or sprinkler
irrigation. Thus, controlling sediments in surface irrigation
return flows will also control the biocides.
There are three ways to control sediments and associated nutrients
and biocides in surface irrigation return flows: (1) Reduce or
eliminate surface irrigation return flow; (2) reduce or eliminate
soil erosion so that there will be little sediment in surface
runoff from irrigation; and (3) implement practices that will re-
move sediments and associated nutrients and biocides from ir-
rigation return flows before these waters enter natural streams. The
last two ways will be necessary for adequate control if surface
return flows cannot be eliminated.
The awareness of the need for sediment and associated nutrient and
biocide control in surface irrigation return flows, coupled with
economic incentives or direct economic benefits of new control
technology, should stimulate farmer and irrigation company accept-
ance of control technology.
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SECTION II
RECOMMENDATIONS
L. Technology available for controlling sediments and associated
nutrients and biocides in surface irrigation return flows should
be promoted through education programs such as workshops, field
observations, limited demonstrations on farmers' fields and other
training experiences.
2. Incentive programs such as low interest loans or cost participation
programs should be developed for farmer and irrigation company
implementation of erosion and sediment control practices on ir-
rigated land. Direct economic benefits of implementing control
practices should be projected and publicized where possible.
3. Research effort should be intensified toward integrating basic
relationships among erosion and sediment control parameters in-
cluding stream size, flow velocity, furrow slope, run length,
sediment settling velocity and forward velocity into new control
technology. Simulation modeling with predictive equations should
be used to assess the relative importance of the various parameters
so that control measures can be applied first to parameters that
will have the most impact upon control.
4. Additional design, construction and operational criteria for sedi-
ment retention basins need to be developed. Sediment retention
basins will be needed to remove sediments from surface irrigation
return flows until techniques can be developed to prevent sediment
losses from highly erosive soils. Economic uses of the sediment
collected in these basins should be developed to reduce the net
costs of cleaning.
5. Efforts to develop and improve irrigation methods that apply
water efficiently, without erosion, at a low cost with low energy
requirements should receive major attention and support. These
efforts should include the design and improvement of irrigation
water delivery systems that will deliver water to farms on
demand.
6. Intensified research efforts should be directed toward developing
field management practices for erosion and sediment control.
These should include, but not be limited to, within-row irrigation,
minimum tillage, grass buffer strips, tailwater control, residue
management, and land forming.
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SECTION III
INTRODUCTION
Surface irrigation return flow is that portion of the irrigation water
applied to soil which passes over the soil surface and becomes runoff.
On an irrigation project it usually also includes direct spill from
canals and water that flows through farm ditches but is not applied
to the soil. Typically, about 10 to 30% of the water applied to
furrow-irrigated land becomes surface runoff. Surface irrigation
runoff can also occur from lands irrigated by wild flooding, some border
streams, and where sprinkle systems apply water too rapidly on sloping
land. Surface irrigation return flows from these latter three situa-
tions comprise only a small portion of the total flows. There is no
surface runoff from fields when the water application rate is equal to
or less than the infiltration rate. Such application rates can be
achieved with properly designed sprinkle irrigation systems and with
trickle irrigation, but the expense and energy requirements of these
systems limit their use. Surface irrigation return flow does not exist
with subsurface irrigation or with certain border irrigation and furrow
methods that confine applied water to a given area, including pumpback
systems.
Water passing over the soil surface has limited contact and exposure to
the soil at the soil surface, and flow at the interface is into the
soil. Therefore, the quantities of soluble salts, fertilizer nutrients
and pesticides dissolved or washed off the soil into the water flowing
over the surface are expected to be extremely small. Such water does
pick up debris, crop residue, applied manure residue, neiaatodes, plant
pathogens, and other foreign matter. When erosion occurs, the most
important material picked up is soil and material attached to it. Soil
picked up in the erosion process is usually referred to as suspended
sediment or sediment.
Erosion of irrigated land has been recognized as a serious problem
for many years. Israelsen et_ ad. (1946) stated that excessive erosion
of irrigated lands was adverse to the perpetuation of permanent agricul-
ture in arid regions. Gardner and Lauritzen (1946) reported that it was
apparent to every farmer that serious damage resulted when attempting
to irrigate steep slopes unless the stream was very small. They recognized
that little erosion occurred on lands with gentle slopes even with
relatively large streams. These observations led them to suggest the
vital importance of finding a means of estimating the rate at which
soil would erode with various stream sizes at various slopes.
-------
Today, 30 years later, it is still common to observe furrow irrigation
on steep slopes with streams that are too large, resulting in serious
erosion. Much technology has been developed to control erosion of
irrigated land and to reduce sediment concentrations in surface
irrigation return flows, but much of this technology has not been applied.
Hence, serious erosion still exists on furrow irrigated land.
The purposes of this report are to provide an overview and an assess-
ment of the problems associated with sediment and adsorbed nutrients
and biocides in surface irrigation return flows, to assess currently
available technology for implementing control measures, and to suggest
research and demonstration needs for improving control.
The available literature has been reviewed, evaluated and summarized, and
results from some current investigations have been incorporated to
provide this state-of-the-art report. Gaps in available technology are
identified, and research and development needs for reducing or eliminating
sediments and adsorbed nutrients and biocides from surface irrigation
return flows are suggested and discussed.
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SECTION IV
SEDIMENTS AND ADSORBED NUTRIENTS AND
BIOCIDES IN SURFACE IRRIGATION RETURN FLOWS
EROSION ON IRRIGATED LAND
Whenever water flows over cultivated land, erosion may occur. Factors
influencing the amount of erosion include (1) the slope in the direc-
tion of irrigation, (2) the stream size, (3) the soil texture, (4) the
condition of the soil surface, (5) the duration of the irrigation, and
(6) the crop. Most erosion on irrigated land results from furrow ir-
rigation, and basically is erosion of the furrows. Israelsen et al.
(1946) reported that furrows near the head ditches eroded 2.5 to 10
centimeters (cm) (1 to 4 inches) in sugarbeet fields. Mech (1959)
showed similar results with row crops. He reported soil losses of
50 metric tons(tonnes)/hectare (t/ha) (22.7 tons/a) during a 24-hour
irrigation of corn on a Sagemoor fine sandy loam soil on a 7%
slope. He further stated that even on relatively flat fields with
short runs, 30 cm (12 in.) of surface soil have sometimes been lost
after about 10 years of cultivation. Similar loss rates have been
observed in the 1970's on irrigated Portneuf silt loam planted to dry
beans, sugarbeets, and corn.
In furrow irrigation, each furrow functions as the absorbing surface
and as a channel for conducting water to irrigate the remainder of the
run (Mech and Smith, 1967). The stream size at the head of the furrow
must be sufficient to meet the infiltration requirements over the
entire furrow length and to propagate the stream to the end of the
furrow fast enough to give a reasonable uniform distribution throughout
the length of run. Ideally it should not exceed that size. Larger
streams are required to irrigate longer runs. But larger streams
have greater capabilities to erode soils and transport sediment on sloping
land, and thereby cause more erosion. Therefore, more erosion would be
expected near the heads of furrows where irrigation runs are long.
Practically, short irrigation runs have not been used because cross
ditches interfere with equipment during tillage, seeding, culti-
vating, and harvesting operations. Shorter irrigation runs require
more labor. Also, it is difficult to control furrow stream sizes
so that just enough water is added to each furrow during the irrigation
to supply the needed water for the run length because infiltration
generally changes during the irrigation and considerable variability
exists between furrows. As a result of these practical factors,
irrigation runs are usually longer than ideal for erosion control, and
furrow stream sizes are generally larger than required for irrigating
the run length to assure that all furrows are irrigated sufficiently
during an irrigation. These practices increase erosion, particularly
at the heads of the furrows.
-------
Mech and Smith (1967) reported the characteristics of flow and silt
load along irrigation furrows (Table 1) in two closely controlled
tests. The flow was carefully controlled into each furrow, and the run-
off and sediment loss were measured from the upper, middle, and lower
third of each furrow. The run length was 274 meters (m) (900 ft), and
the slope was 2%. The flow into each furrow was about 15% greater in
test 2 than in test 1. The results from these field tests clearly
illustrated that erosion was greatest where the stream size was largest.
Soil loss was much greater from the upper third of the furrows than
from the middle and lower thirds. Furthermore, the soil loss was greater
in test 2 where flow was 15% more than in test 1. The soil eroded from
the upper third was deposited in the middle and lower thirds as the
stream size, and thereby the energy to erode and capacity to transport
sedinent, decreased. Erosion occurred further down the furrow and
sediment was deposited further down the furrow in test 2 because the
stream size was larger along the entire furrow length than in test 1.
The critical stream size where erosion essentially ceased and deposition
began came at a point further down the furrow in test 2. These results
would probably be confirmed by computation of tractive force if
sufficient data were available.
Table 1. WATER FLOW AND SOIL LOSS ALONG IRRIGATION FURROWS (Mech and
Smith, 1967).
Distance
from
upper end
Flow per furrow Soil loss
per minute
Runoff
per furrow
Travel
From point
of
Time
For 91-m
(300-ft)
application distance
m
0
91
183
274
0
91
183
274
ft
0
300
600
900
0
300
600
900
liters
26.6
17.0
7.3
2.5
30.6
20.7
11.9
5.4
gal
7.03
4.49
1.94
0.67
8.08
5.46
3.14
1.42
kg
Test no.
0
43.3
4.8
0.4
Test no.
0
51.1
14.2
0.7
Ib
1
0
116
13
1
2
0
137
38
2
%
61
21
2
66
35
8
min
0
48
211
682
0
24
98
436
min
48
163
471
24
74
338
Results from these studies are in contrast to erosion resulting from
rainfall, which is usually most severe down slope where stream sizes
become large enough to erode and where slopes are steepest. Erosion
and soil loss on a sloping irrigated field can be greater from a heavy
rainfall than from irrigation because of the different stream sizes and
locations along the furrows.
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The two tests also demonstrate that much better erosion control and
higher irrigation efficiencies are achieved with short runs because
smaller stream sizes are required. Consider the lower third of the
furrows in test 1. With an inflow of 7.3 liters/min U/min) and an
outflow of 2.5 fc/min, erosion was negligible. If the entire 274-m
run length had been irrigated with the stream size used on the lower
third, the total water requirements would have been 21.9 A/min or
21% less, and there would have been no erosion. Actually, had the
field been irrigated with three separate 91-m run lengths, the inflow
could probably have been less than 7.3 Jl/min because a runoff of 2.5
£/min would not have been necessary. However, 91-m run lengths are
not normally considered practical because field equipment operations
could be much more costly as a result of the extra time required for
turning. New techniques being developed that may allow short run
lengths without interfering with equipment operations will be discussed
later in this report.
The common practice on many irrigated farms today is to place a large
enough stream in each furrow so that the water reaches the lower end
in about 2 to 3 hours for a 12-hour set. This usually allows sufficient
infiltration time to replenish water depleted by the crop without re-
ducing the stream size or requiring other labor during the set. Where
infiltration rates are low, when the application of more water is
desired, and where slopes are nearly flat, 24-hour sets are used. The
irrigating stream must reach the end of the run in about 1/4 of the total
time of irrigation to obtain reasonable uniformity of application
throughout the run. With these practices, the stream sizes are often
large and 40 to 60% of the applied water becomes runoff. This is much
like the upper third of the furrows in the tests reported by Mech and
Smith (1967), and erosion can be extensive.
Another serious erosion problem is associated with the practice common
in some irrigated areas of keeping the drain ditch at the lower end of
the field about 10 to 20 cm deeper than the furrow and at a slope steep
enough that the tailwater flows rapidly away. With this practice, the
ends of the furrows erode rapidly, even with very small streams.
This erosion gradually moves up the slope because erosion increases the
effective slope near the end of the furrow. As the practice is con-
tinued, the slope is increased on the lower 5 to 10 m of the field,
making it difficult to control erosion and soil loss from this portion
of the field, and to achieve adequate intake because of smaller wetted
perimeters. The lower ends of fields may have to be reshaped every
few years because of this practice. This type of erosion is easily
controlled by different tailwater management.
Many fields with steep slopes are irrigated, and usually in the direction
'of the steepest slope, even though it has been recognized for decades
that serious erosion results from irrigating down steep slopes, Israelsen
et al. (1946) clearly demonstrated that more soil was eroded from furrows
with greater slopes. One example they pointed out was that a fivefold
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increase in slope, from 1.15 to 6.07%, increased the erosion 16 times.
The same year, two other publications were released from work done in
Utah presenting the relationships between furrow slope and furrow erosion
(Gardner et_ aJL 1946; Gardner and Lauritzen, 1946). These publications
contain usable graphs illustrating relationships among furrow slope,
stream size, and erosion, and also several useful equations. Unfor-
tunately, irrigation farmers gave little attention to results from
these studies, and today many fields are irrigated with furrow
slopes too steep and with stream sizes that are too large, resulting
in serious erosion.
Following the early work in Utah, numerous investigations were conducted
in other western states relating slope to erosion on irrigated land.
The USDA-SCS Division of Irrigation conducted many tests throughout
the Western USA from 1948 to 1953 to determine maximum non-erosive
stream size as a function of slope. These data suggested a relationship:
Max. Non-Erosive Stream Size, A/sec - °*63
Max. Non-Erosive Stream Size,
slope, %
or (1)
gal _ 10
rain slope, %
Evans and Jensen (1952) studied soil loss from furrows disturbed
by a recent cultivation so that the soil surface was loose and from
furrows that had not been cultivated since a previous irrigation.
Furrow slopes were 1, 2, and 3.5% and stream were 0.38, 0.76, and
1.14 A/sec (6, 12, and 18 gal/min). Their results showed little erosion
with stream sizes of 0.38 and 0.76 fc/sec (6 to 12 gal/min) at 1% slope,
but considerable soil was lost at the steeper slopes and particularly with
a stream size of 1.14 £/sec (18 gal/min). Mech (1949) investigated the
effects of stream size and slope on erosion in irrigation furrows at
Prosser, Washington. His results were similar to those reported from
earlier work. All of the work to date suggests that erosion may
be expected on most row-cropped soils when slopes exceed 1%. Erosion
may be controlled reasonably well on slopes up to 2% if the stream
size is carefully controlled.
The foregoing discussion suggests that there is an optimum stream
size for controlling erosion for a given furrow, soil, and crop condition.
In alfalfa, grass, and other close growing crops, large furrow streams
can sometimes be applied at slopes of 7% or more without much erosion
(Mech, 1949). In contrast, serious erosion can occur in row crops when
stream sizes are too large even at slopes of 1%.
Public Law 92-500, which includes requirements to regulate the quantity
of sediment in surface return flows, has increased the interest among
farmers and irrigation districts to control erosion and sediment in
surface return flows. Many questions raised about erosion and sediment
loss indicate that few irrigators and other personnel associated with
irrigation have a good concept for visual determination of erosion in
furrows. Equation (2) is a simple relationship for estimating soil
erosion in tonnes/ha (t/ha).
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2
., . t 1.2 x eroded area, cm
Soil erosion. — = -
ha furrow spacing, ra
3 3
Equation (2) assumes a soil bulk density of 1.2 g/cm or t/m . (Metric
abbreviations are: m = meters, cm = centimeters, g = grams, t = tonnes,
or metric tons, and ha = hectare.) An alternative to using equation
(2) would be to use Figure 1 to estimate the amount of erosion in
either metric or English units.
Equation (3) is a simple relationship for estimating the furrow length
necessary to contribute 1 tonne of sediment.
Furrow length to erode 1 tonne = 1>2 x area° eroded', cm2 (3)
The furrows shown in Figure 2 have eroded at a rate of 100 t/ha (45 tons/
acre) near the head ditch. The cross section of the eroded area in these
furrows was approximately 70 cm (12.5 in ).
SEDIMENT IN SURFACE IRRIGATION RETURN FLOWS
Sediment concentrations in surface irrigation return flows vary widely.
Brown £t_ al. (1974) reported concentrations ranging from 20 to 15,000 ppm.
Data in Table 2 illustrate the wide sediment concentration variation
in some drains during an irrigation season. These data were collected
from the five main drains from the 82,030-ha Twin Falls tract and the
six main drains from the 65,350-ha Northside tract in southern Idaho.
Sediment concentrations were measured at the point where drain waters
returned to the Snake River, except for the Kimberly and Hansen drains
which were subunits within the Twin Falls tract. These two
drains emptied into canals from which water was redistributed for ir-
rigation. The monthly mean sediment concentrations in the water
diverted from the Snake River and reaching the two tracts are shown
in the last two lines of Table 2 for comparison. The sediment con-
centrations in most drains exceeded those in irrigation water several-
fold. An exception was the W drain, which serves much like a sediment
retention basin. Water from this drain was being returned to the
river with about the same sediment concentration as in the irrigation
water. Brown et al^. (1974) also presented total sediment inputs and out-
puts for the two large irrigation tracts and within-tract erosion and
sediment deposition.
These studies showed that the Northside Canal Company lost 12,080 t
of sediment from their system in 1971. The company mechanically
removes about 295,000 t from canals and drains annually. The Twin
Falls Canal Company, on the south side of the Snake River, returned
113,060 t of sediment to the Snake River in return flows and mechani-
cally removes an estimated 78,000 t from canals and drains annually.
These quantities of sediment represent average soil losses of 4.0 t/ha
(1.76 tons/A) for the Northside Canal Company and 1.42 t/ha (0.62 tons/A)
for the Twin Falls Canal Company - neither of which is considered
excessive by present standards.
10
-------
500
200
100
50
20
10
or
1.0
0.5
0.2
O.I
0.05
0.02
001
ERODED AREA, iriz
0.02 0.05 O.I O2 0.5 1.0 2
10
T I I I I I I
J I I I I I I I I
200
100
50
20
10
5
o
in
c
o
1.0
0.5
o
CO
0.2
01
0.05
0.02
001
O.I 0.2 0.5 1.0 2 5 10 20 50 100
ERODED AREA, cm2
Figure 1. Soil loss rate as a function of eroded cross-
sectional area, and furrow-spacing, for a soil
bulk density of 1.20 g/cm .
11
-------
Figure 2. Erosion occurring under surface irrigation of 2
percent slope land. These furrows were eroding
at the rate of 100 t/ha (45 tons/a) at the point
shown.
I.'
-------
Table 2. SEDIMENT
THE 1971
CONCENTRATIONS IN IRRIGATION AND DRAINAGE WATERS TOR TWO LARGE TRACTS DURING
IRRIGATION SEASON, PPM
Drain
4/20 5/3 5/17
K 240 190 270
N-32 380 100 150
J-8 1,580 1,430 2,610
S 320 350 110
U-26 160 80 100
W 160 50 60
5/28
140
120
510
140
60
30
SarnpJ-ing
6/7 6/15 6/29
Northside Canal Company
200 160 110
170
660
100
100
30
90
660
200
130
40
70
300
440
100
20
date
7/13
120
30
80
110
60
20
7/26
90
180
170
130
160
30
8/10
90
20
110
90
100
20
8/24
90
20
70
60
40
20
9/8 9/28
40 40
60
100
130
50
10
50
110
140
50
40
Twin Falls Canal Company
Rock Creek — — —
Cedar Draw — — —
Filer Drain — — —
Mud Creek — — —
Deep Creek — — —
4/20
Hans en Drain — — —
Kimberly Drain — — 4,180
April
Northside 63
Twin Falls 74
5/25
540
200
710
260
200
5/14
1,550
1,080
May
63
40
6/2
300
210
400
180
110
5/26
380
360
6/15
140
100
210
140
70
6/23
510
610
June July
29
52
37
85
6/29
190
120
710
130
80
7/6
7/13
310
220
2,250
120
60
7/20
3,180 14,500
2,860
Canal
August
33
55
1,420
Waters
Sept.
26
29
7/26
320
550
2,120
200
70
8/3
4,970
4,960
Oct.
26
29
8/10
390
520
1,410
190
110
8/17
290
180
Nov.
26
29
8/24
200
330
820
250
100
9/2
3,160
150
Dec.
—
29
9/8
120
150
270
260
100
9/16
280
70
9/28
150
200
290
130
90
10/5
—
40
-------
Sediment deposited in canals can cause operational difficulties by
blocking gates and turnouts. Allowance for sediment deposition in
canal systems requires that the system be built larger than would
otherwise be necessary. Also, sediment deposits in canals are
usually removed with a dragline at current costs of 50<: to $1.00 per
cubic meter of material.
Carlile (1972) reported suspended solid concentrations ranging from
751 to 7,850 ppm for surface irrigation return flows from the Rosa
Irrigation District in the Yakima River Basin of central Washington.
The irrigation water applied contained only 91 ppm. Fitzsimmons et al.
(1972) measured mean total solids concentrations of 1,550 ppm in
surface runoff from 79 sites on irrigated land in the Boise Valley of
Idaho. They attributed most of the total solids to sediments.
Factors other than the amount of soil eroded from the fields influence
the sediment concentration in surface irrigation return flows. One is
the flow velocity in the drains. When drain flow velocities are low,
sediments settle in the drain channels and require mechanical
removal. Passing drainage water through sediment retention basins can
remove 60 to 95% of the suspended sediment from some surface drainage
waters before they are discharged to a river (Robbins and Carter, 1975).
When surface runoff waters are used to irrigate grass pastures and other
close-growing crops, most of the suspended sediments are removed. This
reuse practice merits consideration as a means to control sediment in
surface irrigation return flows.
Damage to the productivity of cultivated land from topsoil loss from
erosion depends largely on the amount of topsoil available. An annual
soil loss of 11 t/ha (5 tons/a) is considered allowable if the soil
profile contains subsoil which will develop into topsoil or otherwise
can be enriched with organic matter and fertilizer nutrients. A loss
of 11 t/ha represents a soil depth loss of 0.80 mm (0.03 in). At this
erosion loss rate, 0.5 m (about 20 in) of soil would be lost in about
625 years. Where soils are shallow over bedrock, erosion losses are
more critical.
Some data on erosion and sedimentation costs for nonirrigated agricul-
tural land may be used for comparison. Stallings (1950) reported that
erosion reduced corn yields from 5.3 to 8.8% per 2.5 cm (inch) of
topsoil lost. Gottschalk (1962) estimated that the loss, of gross income
to farmers from reduced corn yields in a 2,528-ha (6,246-acre) Illinois
watershed would amount to $1.87 million over a 50-year period, or about
$14.79/ha per year ($6.00/a per year). Narayanan et_ al. (1974), in a
study of five watersheds in Illinois, estimated that loss of income
associated with the loss of productivity from erosion ranged from $1.00
to $10.00/ha per year (40
-------
in reservoirs, and drainage ditches; flooding; and loss of recreational
benefits. Soil losses ranged from 0.52 to 52 t/ha (0.23 to 23 tons/a)
in these studies. Conclusions were that the effect of erosion on the farm
costs about 1% of farm net income and that change of farming practice
due to this cost was not likely. The effect of erosion on farm income
losses does not represent all of the economic impact of erosion. The
damages from eroded sediment, where it deposits, on downstream use, etc. ,
range from 0 to 12 percent of the annual net farm income (Lee, et al.,
1974). Similar relationships are likely for irrigated agricultural land.
NUTRIENTS IN SURFACE IRRIGATION RETURN FLOWS
Nutrients in surface irrigation return flows are in dissolved forms or
they are attached to sediments eroded from the land. Bondurant (1971)
showed mathematically that little soluble nutrient pickup could be
expected to result from nutrient diffusion out of the soil into water
passing over the soil surface, and he presented field data to verify
his contention. Carter et al. (1971) found that soluble nutrient and
salt concentrations in surface irrigation return flows are essentially
the same as those in the applied irrigation water, providing additional
evidence that appreciable soluble nutrients are not picked up by water
passing over the soil surface. Edwards j£ a!U (1972) stated that once
nitrate enters the soil surface, it does not re-enter surface runoff.
Fitzsimmons e£ al. (1972) and Naylor and Busch (1973) reported that
nitrate and ammonium nitrogen concentrations were about the same in
surface runoff as in the irrigation water. A higher organic nitrogen
concentration in the tailwater than in the irrigation water was at-
tributed to the organic matter associated with sediment lost from the
fields and to plant debris picked up and carried from the field by
runoff water. Their studies, along with those of Naylor et_ al. (1972),
illustrated that nitrogen concentrations in surface irrigation return
flows from fields can be markedly increased when liquid nitrogen is
added to the irrigation water for fertilizing the crop. Fertilizer
nitrogen losses from this practice were proportional to the fraction
of the applied water that became surface runoff during the fertilizer
application. Carlile (1972) also found little difference in nitrate
nitrogen concentration in surface runoff and the irrigation water.
Results from the investigations discussed indicate that the concentra-
tions of soluble nitrogen forms in surface irrigation return flow
are usually about the same as the concentration in the applied irrigation
water except when soluble nitrogen is added to the irrigation water.
Another source of soluble nitrogen is decaying plant material with which
the water comes in contact. Organic and total nitrogen concentrations
may be greater in the surface irrigation return flow than in the ir-
rigation water when the water contacts decaying plant material. These
differences are directly associated with the organic nitrogen in the
organic matter of the soil eroded from the fields.
15
-------
Phosphorus is tightly held by soil, and essentially all phosphorus in
surface irrigation runoff is associated with sediment. Fitzsimmons
et al. (1972) and Naylor and Busch (1973) reported greater total
phosphorus concentrations in surface irrigation return flow than
in the irrigation water, and these greater concentrations were related
to greater sediment concentrations. Carter et_al^(1974) and Carter
et al, (1976) have extensively studied phosphorus-sediment relationships
in irrigation return flows. Their results show that total phosphorus
and sediment concentrations in surface runoff are closely related, but
that no such relationship exists between soluble orthophosphate and
sediment concentrations. A regression equation was developed relating
sediment and total phosphorus concentrations as follows: sediment concen-
tration, ppm - 140 + 0.72 (total phosphorus concentration, ppm), with an
r value of 0.94. These data were collected from surface irrigation
return flows in main drains from two large irrigated tracts, 82,030
and 65,350 ha, and therefore represent a wide spectrum of conditions.
Data reported by Carlile (1972) also show a close relationship between
sediment and total phosphorus concentrations in return flows.
Water-soluble orthophosphate concentrations in surface irrigation return
flows are usually less than 1 ppm (Carter, et^al^, 1974; Fitzsimmons,
et sd^,, 1972). Occasionally a condition arises where the soluble
organic phosphorus concentration is high enough to be important.
Under special conditions where water is in contact with dead plant
material, sufficient organic P may dissolve to ghow a P enrichment
in the surface runoff (MacKenzie and Viets, 1974).
BIOCIDES IN SURFACE IRRIGATION RETURN FLOWS
There is little published information on biocide concentrations in
surface irrigation return flows. Table 3 presents data for some bio-
cides in drainwater in California (Johnston, e£ al.,1967). Considerable
information has been published on biocide concentrations in surface
runoff from nonirrigated lands. A review of that literature suggests
that, except where biocides are applied to the water or where they are
washed off the plant material by rain, the biocides in surface runoff
are adsorbed to sediments. This appears to be true also for biocides
in surface runoff from irrigation (Evans, and Duseja, 1973). Unpublished
data from analyses of surface drainage waters and sediments from the
Twin Falls and Northside irrigation tracts in southern Idaho similarly
showed that biocides are generally adsorbed to the sediments.
16
-------
Table 3. IDENTIFIED CHLORINATED HYDROCARBON AND THIOPHOSPHATE
PESTICIDES DETECTED IN SURFACE DRAIN WATER IN THE SAN
JOAQUIN VALLEY, CALIFORNIA * (Johnston, e£ ad., 1967)
Reported concentrations in
parts per billion (ppb)
Times
detected
Maximum
Minimum
Average
DDE
DDD and/or DDT
Dieldrin
Heptachlor Epoxide
Lindane
Toxaphene
Thiodan-Endusulfan
Methoxychlor
Baytex-Fenthion
Ethion
Malathion
Methyl Parathion
Parathion
Thimet
Chlorinated Hydrocarbons
12 0.15
54 5.70
1 0.12
6 0.10
7 0.22
60 7.90
1 0.21
1 0.45
Thi opho sp ha t e s
4 0.16
11 1.20
7 0.32
3 6.40
19 3.60
1 0.03
0.01
0.06
0.12
0.01
0.01
0.10
0.21
0.45
0.03
0.02
0.06
0.30
0.02
0.03
0.06
0.61
0.12
0.02
0.07
2.01
0.21
0.45
0.09
0.26
0.12
2.53
0.52
0.03
* Panoche Drain, Western Fresno County, California that collects both
surface and subsurface drainage waters.
17
-------
SECTION V
TECHNOLOGY AVAILABLE FOR CONTROLLING SEDIMENTS AND ASSOCIATED NUTRIENTS
AND BIOCIDES IN SURFACE IRRIGATION RETURN FLOWS
There are three ways to control sediments and associated nutrients and
biocides in surface irrigation return flows. One is to reduce or
eliminate surface irrigation return flow. The second is to reduce or
eliminate soil erosion so that there will be little or no sediment in
surface runoff from irrigation. This is a good objective, but to reach
it, time will be required for implementing known practices and for
developing and applying new technology. The third way is to remove
sediments and associated materials from surface irrigation return flows
before these waters enter natural streams. Any farmer or irrigation
district making sufficient progress on the first and second ways so that
sediments and associated materials are reduced below problem levels will
no longer need the third. Such progress should be the aim of irrigated
agriculture, with the recognition that many years may be required to
achieve it. However, much immediate progress could be made if presently
available technology were applied.
ELIMINATING OR REDUCING SURFACE IRRIGATION RETURN FLOWS
There are irrigation methods that produce no runoff. These include
properly designed and operated sprinkle systems, basin, trickle, and
some border irrigation and level furrow methods. These methods all have
limitations. Energy requirements for sprinkle systems are high and
energy resources are limited. Batty et_ al_, (1975) recently compared the
energy inputs involved in installation and operation of various sprinkle
and surface irrigation systems. Compared on a total annual energy basis,
surface irrigation systems required 10 to 22% as much energy as sprinkle or
trickle systems where some pumping energy was required for surface
systems (Table 4). Energy requirements would be less for gravity surface
systems than for those using pumping. A design summary showing the
assumed efficiencies, required flow, and horsepower and quantities of
pipe and leveling is given in Table 5.
The capital investment is high for center pivot, side roll, and solid
set sprinkle systems, even though saving in labor costs associated with
these systems over several years partially offset the capital invest-
ment. There are serious labor availability and cost problems associated
with hand-moved sprinkle systems. Furthermore, serious erosion problems
can result from improperly designed and operated sprinkle systems where
the application rate exceeds the intake capacity of the soil (Pair, 1968).
Sprinkle irrigation is an efficient means of applying water to land for
crop production even though this method has the disadvantages discussed
in the preceding paragraph. Sprinkle systems make possible the irriga-
tion of lands with slopes too steep for surface irrigation and lands
with undulating topography. The sprinkle irrigated acreage is rapidly
18
-------
VO
Table 4. TOTAL ANNUAL ENERGY INPUTS, IN THOUSANDS OF KILOCALORIES (OR GALLONS OF DIESEL FUEL)
PER ACRE IRRIGATED FOR NINE IRRIGATION SYSTEMS, BASED ON 36-IN. (915-mm) NET
IRRIGATION REQUIREMENT AND ZERO PUMPING LIFT (Batty, £t al., 1975)
Installation per
Irrigation
system
(1)
Surface without Irrigated
Runoff Recovery System
Surface with Irrigated
Runoff Recovery
System
Solid-set sprinkle
Permanent sprinkle
Hand-moved sprinkle
Side-roll sprinkle
Center-pivot sprinkle
Traveler sprinkle
Trickle
Installation
energy
(2)
103.2
179.9
614.1
493.6
159.7
200.3
388.5
288.9
530.5
Pump ing
energy
(3)
35.2
48.0
770.0
770.0
804.0
804.0
864.0
1,569.0
468.0
pumping energy
ratio
(4)
2.93
3.75
0.80
0.64
0.20
0.25
0.45
0.18
1.13
Labor
energy
(5)
0.50
*
0.30
0.40
0.10
4.80
2.40
0.10
0.40
0.10
Total
energy
(6)
138.9
(15.0)
228.2
(24.6)
1,384.0
(149.5)
1,263.7
(136.5)
968.5
(104.6)
1,007.1
(108.8)
1,252.6
(135.3)
1,858.0
(200.7)
998.6
(107.8)
3These figures were obtained by dividing the installation energy by the system life and by the net
acres irrigated and multiplying by 1.03 to include annual maintenance energy for all systems except
for solid set where 1.01 was used.
Conversion factors: 1 kcal = 4.19 kJ; 1 kcal = 0.000108 gal of diesel.
-------
Table 5. DESIGN SUMMARY OF NINE IRRIGATION SYSTEMS (Batty et_ al., 1975)
N>
O
Irrigation Irrigation , Area .,
systems efficiency — irrigated Flow,—
Surface without
Irrigated run-
off recovery
system
Surface with ir-
rigated run-
off recovery
system
Solid-set sprinkle
Permanent
sprinkle
Hand-moved
sprinkle
Side-roll sprinkle
Center-pivot
sprinkle
Traveler sprinkle
Trickle
%
50
85
80
80
75
75
80
70
90
a
156
155
158
158
158
158
125
152
158
gal/min
1,300
1,300
500
1,275
1,275
1,300
1,300
974
1,300
1,153
Head
ft
5
5
30
175
175
173
173
196
312
115
Power
hp
2
2
5
75
75
76
76
65
136
45
Pipe , Alumi-
PVC- num
tons tons
0.26
2.66 5.00
7.11 38.10
30.46
7.11 2.78
7.11 4.76
4.18
9.71 0.03
18.62
Other
equipment
tons
9.53
10.56
9.61
2.80
17.50
8.32
0.85
Earth Work
Grading Ditching
cu yd ft
128,000 7,890
131,500 7,890
3,750
147,180
3,750
3,750
1,500
5,107
7,826
a/
— Assumed numbers for determining system capacities for the specific systems as designed for a net capacity
of 0.33 in./day (8.4 mm/day). These numbers are relatively high because of field topography.
— A 1300 gpm capacity well was assumed.
c/
— Trickle irrigation required 14.38 tons of polyethylene in addition to the 18.62 tons of pipe.
Conversion factors: 1 acre = 0.405 ha; 1 gpm = 3.78 ft/sec; 1 ft = 0.305 m; 1 hp = 746 W; 1 ton = 907 kg;
1 cu yd = 0.764 m.
-------
increasing. Where land slopes are too steep to be irrigated by surface
methods without serious erosion and sediment runoff, sprinkle irrigation
is the most economical alternative. If all such irrigated lands were
sprinkle irrigated with properly designed and operated systems, there
would be marked reduction in surface irrigation return flows and
sediments and associated nutrients and biocides in these flows.
In some older irrigation systems, runoff and erosion have been greatly
reduced by changing from surface to sprinkle irrigation. On the Osgood
project near Idaho Falls, Idaho, water deliveries were reduced by
approximately 50% by conversion to sprinklers. However, conversion to
sprinkle irrigation is not the answer for all runoff and erosion prob-
lems. The larger, center pivot systems apply water at high rates and
may cause considerable runoff and erosion.
Trickle or drip irrigation is a new, efficient method undergoing rapid
development. This method is particularly well adapted to tree fruit,
cane fruit, vine and other high-value crops. There is no erosion
or surface irrigation return flow from this method, but current
costs of trickle systems are too high for most crops. Also, elaborate
filtering systems are sometimes required to maintain uniform ap-
plication rates with trickle systems. Where the crop value and the cost
of the water saved justifies the cost of trickle irrigation systems,
this method has a great potential for efficient water use without sur-
face irrigation return flow problems. The Second International Drip
Irrigation Congress held in San Diego, California, July 7-14, 1974,
indicated a great worldwide interest in trickle irrigation systems,
their design and operation. Future development of this irrigation
method may reduce costs and make the method economical for use with
more crops. Where drip irrigation is feasible, it could be recommended
as a method to eliminate surface irrigation return flow problems.
Basin and border irrigation are limited to nearly level land. Generally,
surface irrigation return flows from nearly level lands contain little
sediment. Therefore, these methods contribute almost no sediment or
associated nutrients and biocides to surface irrigation return flows.
The level furrow systems used in some areas of Texas and Arizona also
are erosion free.
The recirculating or pump-back system described by Bondurant (1969)
and others (Davis, 1964; Pope and Barefoot, 1973) is a useful method
for eliminating or greatly reducing surface irrigation return flows
from farms. This method uses a basin or pond at the lower end of the
field to catch surface runoff. A pump returns the water from the pond
to the top of the field, or to a different field, for reuse as irriga-
tion water. Erosion is not? eliminated and sediments deposited in the
basin must be removed mechanically, but sediment is prevented
from leaving the farm and returning to natural streams. Stringham and
Hamad (1975) have shown how furrow systems can be operated so that
reuse waters can be more easily incorporated into the irrigation cycle.
21
-------
Bondurant and Willardson (1965) found 66 return systems operating in
the Twin Falls area of southern Idaho in 1964. The average contri-
buting area ranged from 90 to 130 ha (225-320 a) and the water was
redistributed to 25 to 30 ha (60 to 75 a) (Table 6).
Completely eliminating or greatly reducing surface irrigation return
flows may cause other problems in the irrigated West. Many farmers
depend wholly or in part upon surface return flows from other areas
for their irrigation water supply. Thus, eliminating surface return
flow from one district may limit the supply to another district. Also,
many irrigation systems operate on a reuse principle. This means that
most of the surface runoff from irrigating the higher elevation lands
is directed back into the canal system and redistributed- for irrigating
land at lower elevation within the district. This process continues
through the district until the lands at the lowest elevation within the
district are irrigated. Often the only surface return flow that enters
natural streams from irrigated tracts is that from the fields at the
lowest elevations in the district. Eliminating or reducing surface runoff
would reduce the quantity of water applied, both for districts as a
whole and for fields within districts, leaving more water in streams
or canals for distributing to those lands formerly dependent upon runoff
for supply. In many instances, this approach would also require redesign
and construction of the water distribution system for present irrigation
districts.
REDUCING OR ELIMINATING EROSION
Controlling slope: Land slope greatly influences erosion. Mech (1959)
and Mech and Smith (1967) summarized extensive work on the effects of
slope on irrigation furrow erosion. Swanson (1960), Swanson and Dedrick
(1967), and Harris and Watson (1971) investigated the effects of slope
on furrow erosion for both irrigated and nonirrigated land. Results
from these studies showed that erosion may be expected on most row-
cropped soils where slopes exceed 1%. Erosion may be controlled reason-
ably well on slopes up to 2% if the furrow stream size is small. Fields
with slopes greater than 2% in the direction of run should be examined
carefully to see if the direction of run should be changed to a lower
slope or if the field can be irrigated by a different method. Contour
furrows are well suited for crops that require ridging, such as corn,
potatoes, and some perennials. The ridges confine the water and reduce
danger of overtopping. Contour farming has not been used widely in
irrigated areas because short rows and turns are not compatible with
use of large equipment.
Land can be graded to reduce the slope near the lower ends to decrease
water flow velocity, thereby causing the sediment to be deposited in
the furrows. This practice can essentially eliminate sediment losses
from the field but it does not reduce erosion at the upper ends of the
furrows. Farmers resist the practice because furrows fill with sediment
and flooding or lateral flow between furrows occurs if the stream size
22
-------
Table 6. SUMMARY OF RECIRCULATING SURFACE IRRIGATION SYSTEMS, SOUTHERN IDAHO,
1964-1965 (Bondurant and Willardson, 1965)
Eden, Hazel ton, and
Murtaugh areas
Pump installations, no.
Area irrigated, avg.
Contributing area, avg.
Total pumping head, ft avg .
Pipeline length, ft avg.
Reservoir storage, a-ft, avg.
Total cost per installation, avg.
Cost per a, avg.
Cost per hp per a, avg.
Pump, turbine type, no.
Pump, paddle wheel type, no.
Pump horsepower, avg.
w/pipe—
16
61.0
261
38.5
1485
1.9
$3746.00
$ 61.40
$ 6.33
11
5
9.7
w/o pipe—
6
75.0
320
9.5
<100
1.8
$2375.00
$ 31.60
$ 3.60
5
0
8.8
Oakley area
w/pipe
26
75.0
250
23.0
777
2.3
$2920.00
$ 39.00
$ 3.48
2
23
11.2
w/o pipe
20
64.0
226
12.0
<100
2.3
$1516.00
$ 23.70
$ 2.60
2
18
9.1
— With pipeline for returning water to distribution system longer than 100 feet.
With pipeline for returning water to distribution system less than 100 feet long.
-------
is not carefully controlled. Leveling the end of the field will reduce the
amount of sediment leaving a field, but does not appreciably affect
the amount of runoff.
Controlling furrow stream size; Excessive stream sizes can cause
serious erosion on sloping land (Mech, 1959; Mech and Smith, 1967).
Devices that positively control the amount of water from the pipeline,
flume, or ditch into each furrow are essential to effective erosion
control and efficient irrigation. Most valves, gates, siphon tubes
and other flow control devices permit small flow adjustments that
remain unchanged until reset. Such equipment is available, but is
often not used or is used incorrectly. Some gated pipe gives excellent
and easy control of stream size, but the stream of water issuing from
the gate may cause considerable erosion where it impacts'the soil.
Also, the gates in some- gated pipe clog readily with debris causing
stream size to change.
Each irrigation furrow increment serves both as an infiltrating surface
for replacing water depleted by the crop, and as a channel conducting
water to irrigate the remaining furrow length. Therefore, the
stream size at the head of the furrow must be sufficient to meet the
infiltration requirements over the entire furrow length. As a result,
the stream size at the head of the furrow is usually large enough to
cause erosion on sloping land unless the run is short. It is imperative
that the furrow stream size be kept as small as possible to meet the
irrigation requirements with reasonable efficiency if erosion and
sediment loss are to be kept low.
A common practice on many furrow-irrigated farms is to use a large
enough stream size so that water will reach the lower ends of the
furrows quickly to assure a fairly uniform water distribution. This
approach also allows making water sets on a regular schedule, usually
morning and evening, without being bothered with the water during the
remainder of the day while involved with fanning operations. This
practice conserves labor, but often causes erosion because generally
stream sizes are larger than needed after the water reaches the furrow
ends. Technology and equipment are available to change this practice.
A greater initial flow is often desired to get the water to the
end of the furrow and allow a uniform intake time. Once the water
reaches the end, the flow should be reduced or cutback to decrease
erosion and runoff. However, when the stream size is reduced for a
given water set, the excess water from the set after the cutback
must be used elsewhere or wasted in most systems with open ditches.
If it is applied to another section of the field or to a different
field, irrigation sets must be started several times during the day,
and irrigation management becomes more complex. Humpherys (1971)
developed several systems for reducing flow in furrows after water has
reached the ends. One system has good potential for reducing stream
size and controlling runoff and erosion while avoiding split sets.
24
-------
The system supplies water to the center point of a gated pipeline equipped
with automated control valves. The entire stream is directed to only
half of the line until water has reaches the end of the furrows receiving
water from that portion, which can be indicated by a detector or timing
device. The entire stream is then directed to the other half of the
line until the water reaches the ends of these furrows. Then the water
is directed to the entire length of gated pipe so that the stream size
into each furrow is only half that of the initial stream for the remainder
of the irrigation. The controls operate automatically in response to
sensing or Aiming devices. Such an approach can greatly reduce erosion,
runoff, and the sediment in irrigation flow and can also solve the
problem of managing the excessive water after a cutback is made. The
use of cutback stream systems such as this requires pipe systems and
automated controls.
It is important that the stream size delivered to the farm be regulated
to assure a constant flow. Otherwise, proper furrow stream size control
cannot be assured. Adequate technology and equipment are available to
assure a constant flow at the delivery point. However, delivery systems
may need to be redesigned in many areas before systems such as the one
described above will be adopted because such systems operate best if
water is available upon demand.
The run length; The run length and the furrow stream size are closely
related because a sufficient stream size must be placed into each fur-
row to meet the infiltration requirements of the entire furrow length.
Obviously decreasing the run length decreases the stream size
requirements. This in turn can reduce the amount of erosion, because
smaller streams erode less. Irrigating a field 300 m long by using three
100-m runs or two 150-m runs would require a smaller stream size and
result in less erosion than irrigating the entire length in one run
(Gardner and Lauritzen, 1946; Mech, 1959; Mech and Smith, 1967).
The multi-set irrigation system developed by Rasmussen et al. (1973)
provides an alternative to cross ditches for shortening the run length.
Aluminum or plastic pipe is used to distribute water at several points
along the furrows, which effectively decreases the run length and
greatly improves stream-size control. Field tests showed that this
system markedly reduced runoff and erosion. The multi-set system
applied a 50-mm (2-in) irrigation with 95% uniformity with only 4%
runoff and 5% deep percolation as compared to a non-cutback check
stream which had 96% uniformity, 62% runoff and 2% deep percolation
(Table 7). Reducing the run length from 152 m to 50 m (500 ft to 165 ft)
and proportionally reducing stream sizes reduced the amount of erosion
to 2%. The multiset system is portable, so the pipe can be removed for
cultivating. Another advantage is that the system can be readily
automated.
Worstell (1975) field tested another adaptation of the multi-set system
in which laterals were buried, so that farm operations could be carried
out without moving the pipe. Plastic pipe with holes drilled into it
at the proper size and furrow spacing were buried below the tillage depth.
25
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Table 7. COMPUTED DISTRIBUTION, OF WATER UNDER MULTISET AND STANDARD IRRIGATION PRACTICES FOR A 50-mm
(2.0-In) IRRIGATION^'
Treatment
practice
Solid set
Downfield
Upfield
Alternate
Check, _.
cut back— , /
not cut back—
Total
applied
mm
(in)
73
(2.9)
56
(2.2)
65
(2.6)
70
(2.7)
86
(3.4)
142
(5.6)
-1 136.5 m (450-ft) run
21
— Uniformity =
Stored
(minimum)
mm
(in) %
51
(2.0)
51
(2.0)
51
(2.0)
51
(2.0)
51
(2.0)
51
(2.0)
70
91
78
73
59
36
divided into
Stored
Deep Runoff
percolation
mm mm
(in) % (in)
17
(0.67)
2.5
(0.10)
11.9
(0.47)
14.0
(0.55)
2.5
(0.10)
2.5
(0.10)
three, 45.5
x 100
5.1
23 (0.20)
2.3
5 (0.09)
2.0
18 (0.08)
4.8
20 (0.19)
30.0
3 (1.18)
89.5
2 (3.51)
m (150-ft) multiset
Uniformity^-
% %
7 75
4 95
3 81
7 78
35 95
62 96
subruns .
Sediment
ppm
4,000
1,200
1,800
1,300
9,600
« , Stored + Deep Percolation
— 0.38 SL/s (6.00 gpm) stream used until runoff started, then cut back to 0.19 £/s (3.00 gpm).
4/
— Not actually run. Computed from cutback check treatment
-------
Water under low pressure in the pipe passes through the holes upward
into the irrigation furrow directly above. Laterals can be placed
at the desired run length. Any runoff from one run length passes on
to the next. The system is fully automated and can be programmed to
add water daily according to ET depletion or less often as desired.
Water application efficiency was very high, there was essentially no
runoff, and there was no erosion with the system during the first
season of testing. Further testing and some modifications of the
system are needed, but it has great potential as a fully automated fur-
row irrigation system with positive water control and a very small labor
requirement. Proper application of the multi-set concept could reduce or
eliminate the sediment in surface irrigation return flows on some irrigated
fields.
Controlling irrigation frequency and duration; Erosion and sediment
loss are highest during the early part of an irrigation after soils
have been disturbed by cultivation. Mech (1959) reported a soil loss
of 39.9 t/ha (17.8 tons/a) from a recently cultivated corn plot during
the first 32 minutes of runoff. The total soil loss of 50.9 t/ha
(22.7 tons/a) for a 24-hour irrigation, occurred within the first 4 hours,
even though runoff slowly increased after that because of decreasing
intake. Based on these results, less sediment should be lost if fields were
irrigated less frequently and for a longer duration, particularly where
irrigations follow cultivations. Increasing the duration may increase
leaching and associated nutrient losses, and decreasing the frequency
may not be practical for shallow rooted crops. Erosion is also slight
with frequent light irrigations that keep the furrows moist. With this
type of irrigation, small streams are used because of the lower initial
infiltration rate of moist furrows and there is no cultivation between
irrigation.
Another practice related to irrigation frequency is alternate furrow
irrigation. With this practice only half as much soil surface is in
contact with flowing water as when water is applied to every furrow.
Erosion and sediment loss should be only about half as much under
alternate furrow irrigation as under every furrow irrigation. However,
the success of alternate furrow irrigation depends upon soil conditions.
Some soils do not permit adequate lateral water movement, or deep
percolation losses may be too great during the increased time required
for lateral movement. But, there are many soils on which this practice
works well. Usually the duration of the irrigation has to be increased
to effectively irrigate the crop.
A study in southern Idaho showed that much runoff resulted from surface
irrigation because farmers lacked knowledge on crop water use and,
consequently improperly timed irrigation applications (USDI, Bureau
of Reclamation, 1971). Also the farmers had a very poor concept of the
amount of water applied. This study led to the establishment of the
irrigation scheduling work now known as Irrigation Management Services.
Cultural practices to control erosion; Tilling the soil contributes
to erosion and to sediment in surface irrigation return flows. Some
erosion is almost inevitable with the first irrigation after tillage
27
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on many fields. Mech and Smith (1967) summarized results from several
investigations that indicated the soil losses from furrows were 10 or
more times greater during the first than during the second irrigation
after cultivation. Brown et al, (1974) found that sediment concentrations
in surface irrigation return flows from two large tracts were much lower
after weeding and refurrowing cultivation of row crops was stopped.
Proper chemical weed control and management changes can eliminate
the need for some cultivations on surface irrigated lands.
Crop residues can be utilized to control erosion. Miller and Aarstad
(1971) showed that erosion can sometimes be eliminated by incorporating
straw into the irrigation furrows. Crop residue provide a physical
resistance that increases infiltration and decreases the flow velocity,
both of which decrease erosion. Residues can also filter sediment from
water. In most furrow-irrigated areas, the general tendency is to clean
till so that there is little crop residue in the furrows. However,
minimum tillage and the no-till techniques are effective for reducing
erosion and have been used with furrow irrigation (Somerhalder et al.,
1971). The practicability of no-till and minimum tillage with furrow
irrigation has not been throughly investigated.
Another approach is to grow the crop in the irrigation furrow. Ras-
mussen (1976) successfully grew dry beans by this method, with high
irrigation efficiency and no erosion. The growing crop slows the flow
velocity in the furrow and the roots hold the soil in place. This
method may not be applicable to all crops, but the concept merits
testing with other crops.
REMOVING SEDIMENT AND ASSOCIATED NUTRIENTS AND BIOCIDES FROM SURFACE
IRRIGATION RETURN FLOWS
Controlling Tailwater; The most important factor in controlling tail-
water is to limit the amount of runoff. The smallest stream that will
irrigate to the end of the furrow will add nearly as much water to the
soil as a larger stream, and the amount of runoff will be much less and
more easily controlled. Practices that will assure more uniform intake
rates of individual furrows need to be developed and utilized for better
runoff control.
The drain ditch at the field end should be shallow and at a low slope
so that water moves away slowly and sediments settle out before the
water leaves the field. Soil checks can be placed at intervals in the
drain ditch so that flows from only three or four furrows enter each
section between checks. This practice forms miniature sediment basins
and the sediment eroded from the furrows settles in the sections of
drain ditch. Where field and drain ditches are adjacent to larger drains
with sod banks for transporting drainwater from several farms, the water
from each checked section of drain ditch can be allowed to trickle
slowly across the sod bank into the larger drain. The grass on the sod
bank filters the remaining sediment from the surface drainage water
and acts as a control section to prevent further erosion.
28
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Grasses and other close-growing crops efficiently filter sediments from
water. Grass buffer strips at tlie end of fields can effectively remove
sediments from surface runoff. For example, Wilson (1967) found Bermuda
grass to be very effective in warmer regions. Irrigating border checks
with silty water showed that water with a turbidity of 5000 ppm could be
lowered to approximately 50 ppm in 152 to 213 m (500 to 700 ft). The
data indicate that velocities were in excess of critical tractive
velocities so that some bed load was moved downstream after having settled
out.
Another alternative is to utilize tailwater to irrigate alfalfa, pasture,
or other close growing crops so that the sediments will be filtered out
before the water reaches a natural stream,
Utilizing sediment retention basins to remove sediments; Much of the
sediment in surface irrigation return flows can be removed in sediment
retention basins. The need to remove sediments from surface irrigation
return flows before they enter natural streams will continue for many
years, even though much can be done to reduce soil loss from irrigated
fields. Basins are a partial cure to the sediment problem, not a preven-
tion. Their construction and periodic cleaning are relatively expensive.
Many new sediment retention basins are being constructed and used in
irrigated areas of the western U.S. Robbins and Carter (1975) reported
that approximately 150 natural or man-made basins larger than 0.2 ha were
on the 82,030-ha Twin Falls Tract. Since their report, more have been con-
structed, and many more farmers are planning to construct them. The
Northside Canal Company plans to construct sediment retention basins
on all six of the main drains carrying surface return flow back to the
Snake River, and three have been constructed. One of these basins was
specifically designed to remove at least 50 percent of the sediment
entering it. It has removed an average of about 70 percent of the sed-
iment over a 3-year period. Most of the time, the sediment concentra-
tion in water leaving this basin is near the concentration in the
diverted irrigation water and sometimes less.
The effectiveness of simple sediment retention basins is illustrated by
a typical basin catching part of the runoff from an approximately 117-
ha (289 a) sub-basin (Robbins and Carter, 1975). The land area drained
was intensively cropped to dry beans, sugarbeets, cereal grains, alfalfa
and some pasture. The soils were highly erodible Portneuf silt loam,
and the slopes varied from less than 1 to about 15 percent along the
furrows. A total of 2390 t (2633 tons) of sediment was deposited in
the 0.45-ha (1.1-a) basin during two irrigation seasons. This represents
a severe erosion loss of 20.5 t/ha (9.14 tons/a) over a 2-year period
from the 117-ha (289-a) area. This figure includes only the sediment
removed by the basin. The sediment removal efficiency exceeded
80 percent when the sediment concentration exceeded 0.1 percent and
was never below 65 percent during the period of operation.
29
-------
Sediment basins for trapping sediment eroded from irrigated fields have
been studied in southern Idaho (Bondurant et al. 1975). Trap ef-
ficiency is directly related to the velocity, settling depth and parti-
cle size. Sedimentation basins can be designed to trap given particle
sizes if the flow rate is known so that velocity relationships can be
established. Major problems in designing sediment basins are to esti-
mate the inflow rates and total amounts of sediment to be stored in the
pond.
Several types and sizes of sediment retention basins can be used to
remove sediments from irrigation return flows. Basins can be located
to receive runoff from individual fields, from entire farms, from
several farms, or along irrigation district drainways. They can be
excavated or located in a natural depression area by constructing a
dike or dam with proper outlet. More information is needed about the
design and operational criteria for sediment retention basins for dif-
ferent conditions.
Sediment collected in basins is a valuable resource that can be
used for many purposes, and it is often salable. Unfortunately, trans-
portation costs from the basins to the use area may be excessive. It
is important to locate basins as near as possible to the point of sedi-
ment use. Where natural depressions can be filled by constructing dikes
or dams to form basins, no transportation is needed. Some cropping area
may be lost while the sites are used for sediment basins, but after these
basins are filled, the drain water can be placed in controlled channels
and the deposited sediment can be farmed along with adjacent farmland,
thus expanding and combining fields into more economical operating units.
Other uses of sediment include landscaping, filling depressions and old
channels in fields, and increasing soil depth over bedrock. A golf course
has been developed by covering basalt with sediment from one district
drainway basin in southern Idaho.
Drainage channels sometimes serve as sediment retention basins. Brown
et al. 1974 and Carter jst. al. 1974 reported the effectiveness of
drains in removing sediment and phosphorus from irrigation return flows
on the 65,350-ha Northside tract in southern Idaho. Many of these
drains were constructed to a grade small enough that the flow velocity
permits sediment to settle.
Particle size segregation takes place as sediments settle in basins or
drains. Sediments remaining in suspension are mostly in the clay size
fraction, although much of the clay settles in aggregates because dis-
persion is seldom complete. Dispersion is greater in waters of low salt
concentrations, and more clay remains suspended in such waters. The
clay size fraction is richer in attached phosphorus than the larger size
fractions, so that passing water through a sediment retention basin can
give an apparent phosphorus enrichment when the phosphorus is measured
per. unit of suspended material. However, recent studies (Carter et al.,
1974) have shown that sediment retention basins conserve phosphorus.
The authors and associates have recently shown that 55 to 65% of the
30
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incoming phosphorus is retained in a sediment retention basin that
removes 65 to 75% of the incoming sediment. On the Northside Canal
Company Tract, 88% of the phosphorus in diverted water was deposited
on the tract. Some of the phosphorus associated with the clay size
fraction is lost through sediment retention basins because it is not
practical to construct basins large enough to remove clay size particles.
The use of sediment retention basins to remove sediments from surface
irrigation return flows can be discontinued for any field, farm, or
district where the implementation of erosion control practices have elim-
inated excessivte sediment concentration in the water. Also, use of
basins for individual fields may not be needed every season. During
seasons when alfalfa, grass, or other close-growing crops are grown
and there is no erosion, the runoff water could bypass the basin. Non-
use for one or more seasons would allow the collected sediment to dry
and allow time for cleaning. Then when the field is returned to the
row crops, the basin could again be used to remove most of the eroded
soil or sediment from the tailwater.
31
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SECTION VI
SIMULATION TECHNIQUES FOR ESTIMATING SEDIMENT AND ASSOCIATED
NUTRIENT AND BIOCIDE LOADS IN SURFACE RETURN FLOWS
Many factors influence the sediment and associated nutrients and biocides
in surface irrigation return flows. Simulation modeling techniques could
be useful in providing such information on the relative impact of each
of these factors and their interactions. Once the relative impact of
different factors is determined by these techniques, control practices
can be more effectively applied in the field. Simulation models specific
for estimating sediment and associated nutrients and biocides in surface
irrigation runoff have not been developed, but the literature contains
information useful for predicting erosion and sediment loss. Hornsby
and Law (1972) discussed general concepts for modeling irrigation return
flows with the surface water system as a submodel. Law and Skogerboe
(1972) presented a diagrammatic model of the irrigation return flow system
in which tailwater was a component. Fleming (1975) described some of
the components which are available for use in the simulation process and
presented a sediment flow chart for modeling the sediment flow process
from the field to the stream. He also presented a conceptual sediment
simulation model outlining its basic structure and showing key processes
from precipitation through erosion to reservoirs and channels and ending
at the ocean. This information is not directly applicable to predicting
sediment loss in surface irrigation return flows, but some of the
information would be applicable, especially to sprinkle irrigation.
Development of the Universal Soil Loss Equation (Wischmeier and Smith,
1965) has made possible predicting soil erosion losses under rainfall
with reasonable accuracy. The equation is:
A = RKLSCP (4)
Where:
A = the computed soil loss per unit area;
R = the rainfall factor: The number of erosion-index units in a
normal year's rain. The erosion index is a measure of the
erosive force of specific rainfall;
K = the soil-erodibility factor: The erosion rate per unit of
erosion index for a specific soil in cultivated continuous
fallow, on a 9% slope 72.6 ft long;
L = the slope-length factor: The ratio of soil loss from the field
slope length to that from a 72.6-ft length on the same soil
type and gradient;
S = the slope-gradient factor: The ratio of soil loss from the field
gradient to that from a 9% slope;
C = the cropping-management factor: The ratio of soil loss from a
field with specified cropping and management to that from
the fallow condition on which the factor K is evaluated;
P = the erosion-control practice factor: The ratio of soil loss
with contouring, stripcropping, or terracing to that with
straight-row farming, up-and-down the slope.
32
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Adapting this equation to irrigated land would be a complex and dif-
ficult task. Mech and Smith (1967) discussed such an adaptation.
They suggest that the factor, R, would not apply. The erosive force
is the furrow flow rather than rainfall. Indices for the erosion potential
of different streams would have to be developed. Establishing K values
would involve relating soil erodibility to flow and soil water conditions
associated with furrow irrigation. The length of slope factor, L,
would be resolved into stream flow. The steepness of slope factor, S,
would be determined as the slope in the irrigation furrow. Whether this
grade is the natural slope of the land or is made by contouring would
be immaterial. The S factor would include the P factor. The
crop management factor, C, is very important, because management
determines compaction, detachment, intake rate, permeability, and other
conditions in the furrow at the time water is applied.
Useful information for predicting erosion and sediment loss from ir-
rigated land is available, Gardner and Lauritzen (1946) developed
several graphs relating erosion to stream size and slope. This
information would be useful in characterizing factors L and S for
adapting the Universal Soil Loss Equation to irrigated land. The
equation developed by Evans and Jensen (1952) relating erosion to
stream size and slope factors would be useful in characterizing factor
S and for developing indices for the erosion potential of different
streams. The findings of Tovey et al. (1962) on the effects of soil
moisture at the time of irrigation on erosion would be useful in assessing
factors K and C. Mech (1949) and Mech and Smith (1967) summarized
several studies showing the effects of stream size, furrow slopes,
and different crops, on erosion and sediment loss which would be useful
in characterizing K, L, S, and C factors.
The advance of high-speed computer capability and the development of
modern simulation techniques facilitate predicting sediment and as-
sociated materials concentrations and loads in surface irrigation return
flows. Such a task will not be easy because of the complexity of the
factors involved.
33
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SECTION VII
RESEARCH AND DEMONSTRATION NEEDS
Considerable technology is available for controlling sediments and as-
sociated nutrients and biocides in irrigation return flows. Some of
this technology could be directly applied by farmers, but much of it
needs further development and refinement to be feasible and accept-
able. There is also a need for new technology which will achieve
erosion and sediment control. The basic relationships among stream
size, flow velocity, erosion, and sedimentation, and among run length
slope, stream size, sediment settling velocity, and forward
velocity need to be integrated into new technology that will permit
modification of various control parameters. New ideas are needed, and
new and better water control systems need to be developed.
Public Law 92-500 has greatly increased farmer and irrigation company
interest in applying sediment and associated nutrient and biocide
control measures into irrigation practices. In response to this
interest, programs to provide information on available control tech-
nology should be developed. Demonstration of some control practices
on farmers' fields may be beneficial. In some areas the advantages
of irrigating with smaller streams might be demonstrated. The automatic
cutback and the multi-set systems could be used in controlling erosion
by controlling the stream size. In some cases, the direction of
irrigation could be changed 90 degrees so that slope in the direction
of irrigation would be less. Methods to manage tailwater and the
principles involved might be successfully demonstrated or compared
in some areas. The advantages of fewer cultivations could also be shown.
Other practices could be demonstrated as they are developed.
One reason that available technology for sediment and associated nutri-
ent and biocide control has not been accepted and applied by farmers
is because economic incentives have been lacking. We must remember
that farmers farm to make a living, and that they adopt new practices
that they believe will increase their profits and thereby enhance their
living standard. There has, in the past, been little or no economic
incentive for using erosion control practices. The only incentive has been
preservation of topsoil, and the economic value of topsoil preservation
has been very subtle and difficult to assess in dollars, while costs
of control practices have been measurable. We need to consider who
cares if 0.5 mm of soil is lost each year,if the soil is several meters
deep,and if the loss does not decrease income. There is a need
to show the income benefits or provide economic incentives for erosion
control practices on irrigated land. Another approach would be to
show the economic loss from failure to apply available control prac-
tices. This latter approach could be through enforcement by fining
when sediment, nutrient, and biocide losses exceed established critical
levels, but such enforcement should be used only as a last resort.
34
-------
More research and development is needed on multi-set irrigation and
similar systems that allow small, non-erosive stream sizes and long
farm equipment runs. The buried lateral concept needs further study
and development. Such systems have good potential for erosion control,
but they will be accepted only if costs are not excessive.
More information is needed on within-row irrigation. Conceivably, this
practice would be suitable for corn, peas, cereal grain seeded in
rows, and other crops. This practice is not likely suitable for all
crops. Studies conducted on within-row irrigation should have at
lease two aims. One is to control sediment losses and the other is
to achieve greater water use efficiency.
Another method that should be investigated is grading the field in
the direction of irrigation so that the slope varies from the top to
the bottom of the field. The close relationship between slope, erosion,
and stream size suggests that erosion and sediment loss could be con-
trolled by altering the slope with distance from the top of the field.
Methods for computing and analyzing major leveling and the associated
economics need to be developed.
The use of grass or other close-growing crop buffer strips to filter
the soil eroded from row-cropped fields before tailwater leaves the
field needs to be evaluated. Buffer strips would be more acceptable
if they could be harvested and the crop sold. An alternative to this
approach would be to direct all runoff water from row-cropped fields
onto pasture, alfalfa, or other close-growing crop fields. This would
filter eroded sediments from the water before it entered a natural
stream. Other tailwater management practices to reduce sediment losses
need to be developed.
Additional research is needed to improve cultivation practices toward
fewer cultivations and no-till farming methods as they apply to both
surface and sprinkler irrigated land. Better weed control practices
for irrigated land need to be developed. Methods of predicting erosion
under various cultivations and irrigation practices need to be devel-
oped, particularly in surface irrigation. This information in needed
so that simulation models can be developed to predict benefits of
erosion and sediment control practices. Studies of the applicability
of the Universal Soil Loss Equation for predicting erosion under all
types .of sprinkler systems need to be conducted. The development of
a soil loss equation for furrow irrigated land should be pursued.
Research is needed on the design of irrigation delivery systems which
would facilitate delivery of irrigation water to the farmer on demand
so that the farm irrigation system can be made more flexible.
35
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More information is needed on the design and operational criteria for
sediment retention basins. The Agricultural Research Service and the
University of Idaho are conducting research on this subject, and their
results will provide useful information. However, additional research
on this subject should be encouraged. There are three different kinds
or sizes of basins—field, farm, and district—and more information is
needed on all sizes. Further work is needed on the use of sediment
collected in sedimentation basins and on more economical methods of
cleaning them.
36
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SECTION VIII
LITERATURE CITED
1. Batty, J.C., S.N. Hamad, and J. Keller. 1975. Energy inputs to
irrigation. J. Irrig. and Drain. Div., Proc. Amer. Soc. Civil
Eng. 101(IRA):293-307.
2. Bondurant, J.A. 1969. Design of recirculating irrigation systems.
Trans. Amer. Soc. Agr. Eng. 12:195-201.
3. Bondurant, J.A. 1971. Quality of surface irrigation runoff water.
Trans. Amer. Soc. Agr. Eng. 14:1001-1003.
4. Bondurant, J.A., C.E. Brockway, and M.J. Brown. 1975. Some aspects
of sediment ponds design. 3rd National Symposium on Urban Hydrology
and Sediment Control. Proceedings Paper C4, p. C35-41.
5. Bondurant, J.A. and L.S. Willardson. 1965. Recirculating irrig-
ation systems. Proc. Specialty Conf., Irrig. and Drain Div.,
Amer. Soc. Civil Eng. p. 243-256.
6. Brown, M.J., D.L. Carter, and J.A. Bondurant. 1974. Sediment in
irrigation and drainage waters and sediment inputs and outputs for
two large tracts in southern Idaho. J. Environ. Qual. 3:347-351.
7. Carlile, B.L. 1972. Sediment control in Yakima Valley. Proc.
Natl. Conf. on Managing Irrigated Agriculture to Improve Water
Quality, U.S. Environmental Protection Agency and Colo. State Univ.
P. 77-82.
8. Carter, D.L., J.A. Bondurant, and C.W. Robbins. 1971. Water-
soluble NO.-Nitrogen, PO -phosphorus, and total salt balances on a
large irrigation tract. Soil Sci. Soc. Amer. Proc. 35:331-335.
9. Carter, D.L., M.J. Brown, and J.A. Bondurant. 1976. Sediment-
phosphorus relations in surface runoff from irrigated lands. Proc.
Third Federal Inter-Agency Sedimentation Conf., p. 3-41 to 3-52.
10. Carter, D.L., M.J. Brown, C.W. Robbins, and J.A. Bondurant. 1974.
Phosphorus associated with sediments in irrigation and drainage
waters for two large tracts in southeastern Idaho. J. Environ. Qual.
3:287-291.
11. Davis, J.R. 1964. Design of irrigation tailwater systems. Trans.
Amer. Soc. Agr. Eng. 7:336-338.
12. Edwards, D.M., P.E. Fischbach, and L.L. Young. 1972. Movement
of nitrates under irrigated agriculture. Trans. Amer. Soc. Agr.
Eng. 15:73-75.
13. Evans, J.O. and D.R. Duseja. 1973. Herbicide contamination of
surface runoff waters. Environmental Protection Technology
Series, EPA-R2-73-266.
14. Evans, N.A. and M.E. Jensen. 1952. Erosion under furrow irrig-
ation. North Dakota Agr. Expt. Sta. Bimonthly Bull., Vol. XV,
No. 1, p. 7-13.
15. Fitzsimmons, D.W., G.C. Lewis, D.V. Naylor, and J.R. Busch. 1972.
Nitrogen, phosphorus and other inorganic materials in waters in
a gravity-irrigated area. Trans. Amer. Soc. Agr. Eng. 15:292-295.
16. Fleming, G. 1975. Sediment-Erosion-Transportation-Deposition
Simulation: State of the Art. In Present and Prospective Tech-
nology for Predicting Sediment Yields and Sources. USDA, ARS-S-40,
p. 274-285.
37
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17. Gardner, Willard and C.W. Lauritzen. 1946. Erosion as a function
of the size of the irrigation stream in the slope of the eroding
surface. Soil Sci. 62:233-242.
18. Gardner, Willard, John Hale Gardner, and C.W. Lauritzen. 1946.
Rainfall and irrigation in relation to erosion. Utah Agr. Expt.
Sta. Bull. 326.
19. Gottschalk, L.C. 1962. Effects of Watershed Protection Measured
on Reduction of Erosion and Sediment Damages in the United States.
International Union of Geodesy and Geophysics, Association of
Scientific Hydrology, Symposium on Continental Erosion, Bari, Italy..
Publication No. 59, 1962, pp. 426-450.
20. Harris, Warren S. and William S. Watson, Jr. 1971. Graded rows for
the control of rill erosion. Trans. Amer. Soc. Agr. Eng. 14:577-581.
21. Hornsby, Arthur G. and James P. Law, Jr. 1972. The role of modeling
in irrigation return flow studies. Proc. Natl. Con-f. on Managing
Irrigated Agriculture to Improve Water Quality, U.S. Environmental
Protection Agency and Colo. State Univ. p. 203-210.
22. Humpherys, A.S. 1971. Automatic furrow irrigation systems.
Trans. Amer. Soc. Agr. Eng. 14:466-470.
23. Israelsen, O.W., G.D. Clyde, and C.W. Lauritzen. 1946. Soil
erosion in small irrigation furrows. Utah Agr. Exp. Sta. Bull.
No. 320, p. 39.
24. Johnston, W.R., F.T. Ittihadieh, K.R. Craig, and A.F. Pillsbury.
1967. Insecticides in tile drainage effluent. Water Resour.
Res. 3:525-537.
25. Law, James P. Jr., and Gaylord V. Skogerboe. 1972. Potential for
controlling quality of irrigation return flow. J. Environ. Qual.
1:140-145.
26. Lee, M.T., A.S. Narayanan, and E.R. Swanson. 1974. Economic
Analyses of Erosion and Sedimentation on Sevenmile Creek Southwest
Branch Watershed. Illinois Agr. Exp. Sta., Agr. Econ. Res.
Rep. No. 130.
27. MacKenzie, A.J. and F.G. Viets, Jr. 1974. Nutrients and other
chemicals in agricultural drainage waters. Ch. 18. In J. van
Schilfgaarde (ed), Drainage for Agriculture. Agron. Monograph
17:489-508.
28. Mech, Stephen J. 1949. Effect of slope and length of run on
erosion under irrigation. Agr. Eng. 30:379-383, 389.
29. Mech, Stephen J. 1959. Soil erosion and its control under furrow
irrigation in the arid west. USDA, ARS, Agr. Inf. Bull. No. 184.
30. Mech, Stephen J. and Dwight D. Smith. 1967. Water erosion under
irrigation. In Robert M. Hagan, Howard R. Raise and Talcott W.
Edminister (ed.) Irrigation of Agricultural Lands. Agronomy
11:951-963, Amer. Soc. Agron., Madison, Wis.
31. Miller, D.E. and J.S. Aarstad. 1971. Furrow infiltration as
affected by incorporation of straw or furrow cultivation. Soil
Sci. Soc. Amer. Proc. 33:492-495.
32. Narayanan, A.S., M.T. Lee, and E.R. Swanson. 1974. Economic
Analysis of Erosion and Sedimentation - Crab Orchard Lake Water-
shed. Illinois Agr. Econ. Res. Exp. No. 128.
38
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33. Naylor, D.V. and J.R. Busch. 1973. Effects of irrigation,fertil-
ization, and other cultural practices on water quality. Res.
Tech. Comp. Rep. Idaho Water Resour. Res. Inst. p. 19.
34. Naylor, D.V., G.C. Lewis, D.W. Fitzsimmons, and J.R. Busch. 1972.
Nitrogen in surface runoff resulting from addition of fertilizers
to irrigation water. Proc. 23rd Ann. Pac. NW Pert. Conf. p. 67-73.
35. Pair, C.H. 1968. Water distribution under sprinkler irrigation.
Trans, Araer. Soc. Agr. Eng. 11:648-651.
36. Pope, D.L. and A.D. Barefoot. 1973. Reuse of surface runoff
from furrow irrigation. Trans. Amer. Soc. Agr. Eng. 16:1088-1091.
37. Rasmussen, W.W. 1976. New techniques saves irrigation water.
Agr. Res. 24:14.
38. Rasmussen, W.W., J.A. Bondurant, and R.D. Berg. 1973. Multiset
surface irrigation system. Int. Comm. on Irrig. and Drain. Bull.
p. 48-52.
39. Robbins, C.W. and D.L. Carter. 1975. Conservation of sediment in
irrigation runoff. J. Soil and Water Conserv. 30:134-135.
40. Somerhalder, B.R., D.E. Land, and H.D. Wittmuss. 1971. Increased
corn yields with less tillage. Amer. Soc. Agr. Eng. Mid-Central
Reg. Mtg, April 16-17. Paper MC-71-604.
41. Stallings, J.H. 1950. Erosion of topsoil reduces productivity.
SCS-TP-98.
42. Stringham, Glen E. and Sofa N. Hamad. 1975. Irrigation runoff
recovery in the design of constant flow furrow discharge irrigation
systems. Trans. Amer. Soc. Agr. Engr. 18:79-84.
43. Swanspn, N.P. 1960. Hydraulic characteristics of surface runoff
from simulated rainfall on irrigation furrows. ARS 41-43:90-102.
44. Swanson, N.P. and A.R. Dedrick. 1967. Soil particles and ag-
gregates transported in water runoff under various slope conditions
using simulated rainfall. Trans. Amer. Soc. Agr. Engr. 10:246-247.
45. Tovey, Rhys, Victor I. Myers, and J.W. Martin. 1962. Furrow
erosion on steep irrigated land. Idaho Agr. Expt. Sta. Res. Bull.
No. 53.
46. USDI, Bureau of Reclamation. 1971. Use of Water on Federal
Irrigation Projects-Minidoka Project, Northside Pumping Div.
Unit A., 7 Volumes.
47. Wilson, L.G. 1967. Sediment removal from flood water by grass
filtration. Trans. Amer. Soc. Agr. Engr. 10:35-37.
48. Wischmeier, W.H. and D.D. Smith. 1965. Predicting rainfall-
erosion losses from cropland east of the Rocky Mountains. USDA,
ARS, Agr. Handb. 282.
49. Worstell, R.V. 1975. An experimental buried multiset irrigation
system. Amer. Soc. Agr. Eng. Paper No. 75-2540.
39
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SECTION IX
BIBLIOGRAPHY
1. Ballard, F.L. 1975. Analysis and Design of Settling Basins for
Irrigation Return Flows. Unpublished M.S. Thesis (Agr. Eng.)
University of Idaho.
2. Biggar, J.W. 1966. Factors affecting the appearance of pesticide
in drainage water. In Agricultural Waste Waters, L.D. Doneen,
(ed.), Report No. 10, Water Resource Center, University of Cali-
fornia, p. 113-118.
3. Bondurant, J.A. 1970. Get double use out of irrigation water.
Idaho Farmer 88:24-27.
4. Bower, C.A. and L.V. Wilcox. 1969. Nitrate content of the upper
Rio Grande as influenced by nitrogen fertilization of adjacent
irrigated lands. Soil Sci. Soc. Amer. Proc. 33:971-973.
5. Branson, R.L., P.F. Pratt, J.D. Rhoades, and J.D. Oster. 1975.
Water quality in irrigated watersheds. J. Environ. Qual. 4:33-40.
6. Bristol. A.L. 1973. Phosphorus chemistry of some drainage waters
and sediments from irrigated land in the Boise River Valley. Un-
published M.S. Thesis (Soils), University of Idaho.
7. Brown, L.N. 1951. Irrigation methods to conserve soil and water
on steep lands. Calif. Agr. Ext. Circ. No. 177.
8. Busch, J.R., D.W. Fitzsimmons, G.C. Lewis, and D.V. Naylor. 1972.
Cultural influences of irrigation drainage water, Proc. Specialty
Conf.,•Irrig. and Drain. Div., Amer. Soc. Civil Eng., p. 45-56.
9. Carlson, Ronald D. 1974. A water, nutrient, and sediment budget
for an irrigated farm in the Boise Valley. Unpublished M.S.
Thesis (Agr. Eng.), University of Idaho.
10. Carter, D.L. 1972. Irrigation return flows in southern Idaho.
Proc. Nat. Conf. on Managing Irrigated Agriculture to Improve
Water Quality, U.S. Environmental Protection Agency and Colo.
State Univ. p. 47-53.
11. Carter, D.L. 1976. Guidelines for sediment control in irrigation
return flows. J. Environ. Qual. 5:119-124.
12. Carter, D.L., C.W. Robbins, and J.A. Bondurant. 1973. Total
salt, specific ion, and fertilizer element concentrations and
balances in the irrigation and drainage waters of the Twin Falls
tract in southern Idaho. USDA, ARS-W-4.
13. Coleman, C. 1970. How to recycle runoff. World Irrig. 10:20-24.
14. Comes, R.D., P.A. Frank, and R.J. Demint. 1975. TCA in irriga-
tion water after bank treatment for weed control. Weed Sci.
23:207-210.
15. Griddle, Wayne, D., Sterling Davis, C.H. Pair, and D. Shockley.
1956. Methods for evaluating irrigation systems, USDA,SCS Agr.
Handb. No. 82.
16. Davis, Sterling and S.D. Nelson. 1970. Surface irrigation
easily automated. J. Irrig. and Drain. Div., Proc. Amer. Soc.
Civil Eng., 96(IR1):47-51.
40
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17. Denint, R.J., P.A. Frank, and R.D. Comes. 1970. Amitrole residues
and rate of dissipation in irrigation water. Weed Sci. 18:439-442.
18. DeRemer, R.D. 1970. Starting with trickle irrigation. Reclam-a-
tion Era 56:15-17.
19. Doneen, L.D. (ed.) 1966. Agricultural waste waters. Calif.
Water Resources Center Rep. No. 10.
20. Eldridge, Edward F. 1963. Irrigation as a source of water pol-
lution. J. Water Pollnt. Contr. Fed. 35:614-635.
21. Eldridge, Edward F. 1959. The effect of irrigation on the quality
of water for industrial use. Proc. 14th Ind. Waste Conf.,
104:52-67.
22. Eldridge, Edward F. 1960. Return irrigation water-characteristics
and effects. U.S. Public Health Service, Region IX, Portland,
Oregon.
23. Faulkner, L.R. and W.J. Bolander. 1970. Agriculturally-polluted
irrigation water as a source of plant parasitic nematode infesta-
tion. J. Nematology 2:368-374.
24. Fischbach. P.E. and H.R. Mulliner. 1974. Every-other furrow ir-
rigation of corn. Trans. Amer. Soc. Agr. Eng. 17:426-428.
25. Fischbach, P. E. 1968. Design of an automated surface ir-
rigation system with reuse system. Proc. Nat. Irrig. and Drain.
Specialty Conf., Amer. Soc. Civ. Eng. p. 219-236.
26. Fok, Yu-Si and L. S. Willardson. 1971. Subsurface irrigation
system analysis and design. J. Irrig. and Drain. Div., Proc. Amer.
Soc. Civ. Eng., 97(IR3):447-454.
27. Fox, W.M. 1966. Products of soil erosion in agricultural
effluent. In Agricultural Waste Waters, L.D. Doneen, (ed.)
Report No. 10, Water Resource Center, University of California,
p. 113-118.
28. Garner, B.J. 1971. Irrigators shape their land for water control.
Soil Cons. 36:149-150.
29. Goldberg, D. and M. Shmueli. 1970. Drip irrigation - a method
used under arid and desert conditions of high water and soil
salinity. Trans. Amer. Soc. Agr. Eng. 13:38-41.
30. Hall, J.K., M. Pawlus, and E.R. Higgins. 1972. Losses of atrazine
in runoff water and soil sediment. J. Environ. Qual. 1:172-176.
31. Haney, P.E. and T.W. Bendixen. 1953. Effect of irrigation runoff
of surface water supplies. J. Amer. Water Works Assoc. 45:1160-1171.
32. Hansen, Vaughn E. 1958. The importance of hydraulics of surface
irrigation. J. Irrig. and Drain. Div., Proc. Amer. Soc. Agr.
Eng. Paper No. 1788.
33. Heinemann, W.H. and M.J. Brown. 1972. Fractional water-sediment
sampler. Soil Sci. Soc. Amer. Proc. 36:376-377.
34. Hiler, E.A. and T.A. Howell. 1972. Crop response to trickle
and sub-surface irrigation. Amer. Soc. Agr. Eng. Paper 72-744.
35. Howe, O.W. and D.F. Heermann. 1970. Efficient border irrigation
design and operation. Trans. Amer. Soc. Agr. Eng. 13:126-130.
36. Hurley, P.A. 1968. Predicting return flows from irrigation.
J. Irrig. and Drain. Div., Proc. Amer. Soc. Civ. Eng., 94(IR1):41-48,
37. Jobling, G.A. and A.K. Turner. 1973. Physical model study of
border strip irrigation. J. Irrig. and Drain. Div., Proc. Amer.
Soc. Civ. Eng., 99(IR4):493-510.
41
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38. Kincaid, Dennis C. and Norris P. Swanson. 1974. Rainfall run-
off from irrigation furrows. Trans. Amer. Soc. Agr. Eng. 17:
266-268.
39. Lai, R., and A.C. Pandya. 1970. Furrow irrigation with decreasing
infiltration rate. J. Irrig. and Drain. Div., Proc. Amer. Soc.
Civ, Eng,, 96(IR4):451-460.
40. Law, James P., Jr., Jeffrey D. Denit, and Gaylord V. Skogerboe.
1972, The need for implementing irrigation return flow quality
control. Proc. Nat. Conf. on Managing Irrigated Agriculture to
Improve Water Quality., U.S. Environmental Protection Agency and
Colo. State Univ. p. 1-17.
41. Law, James P., Jr., and Jack L. Witherow. 1971. Irrigation
residues. J. Soil and Water Conserv. 26:54-56.
42. Law, James P., Jr. 1971. National irrigation return flow re-
search and development program. Environmental Protection Agency
Report 13030WRV12/71.
43. Law, James P., Jr., James M. Davidson, and Lester W. Reed. 1970.
Degradation of water quality in irrigation.return flows. Okla.
Agr. Exp. Sta. Bull. B-168. p. 26.
44. Law, James P., Jr. and Harold Bernard. 1970. Impact of agricul-
tural pollutants on water uses. Trans. Amer. Soc. Agr. Eng.
13:474-478.
45. Law, James P., Jr. and Jack L. Witherow (ed.) 1970. Water quality
management problems in arid regions. U.S. Environmental Protec-
tion Agency. Water Pollution Control Research Series 1303
DYY06/69.
46. Lewis, G.C. 1959. Water quality study in the Boise Valley.
Idaho Agr. Expt. Sta. Bull. No. 316.
47. Lyons, C.G., Jr., 1972. Trickle irrigation - a more efficient
means of water management. Texas Agr. Prog. 18:3-4.
48. McGauhey, P.H. 1968. Quality changes through agricultural use.
T_n Eng. Management of Water Quality. McGraw-Hill Book Co., New
York, p. 58-66.
49. Mech, Stephen J. 1960. Soil management as related to irrigation
practices and irrigation design. Trans. 7th Int. Cong. Soil Sci.
1:645-650.
50. Miller, C.W., W.E. Tomlinson, and R.L. Norgren. 1967. Persis-
tence and movement of parathion in irrigation waters. Pestic.
Monit. J. 1:47-48.
51. Muir, J., G.E. Seim, and R.A. Olson. 1973. A study of factors
influencing the nitrogen and phosphorus contents of Nebraska
waters. J. Environ. Qual, 2:466-470.
52. Musick, J.T., W.H. Sletten, and D.A. Dusek. 1973. Evaluation
of graded furrow irrigation with length of run on a clay loam
soil. Trans. Amer. Soc. Agr. Eng. 16:1075-1080.
53. Neal, O.K. 1944. Removal of nutrients from the soil by crops
and erosion. Agron. J. 36:601-607.
54. Nicolaescu, I. and E.G. Kruse. 1971. Automatic cutback furrow
irrigation system design. J. Irrig. and Drain Div., Proc. Amer.
Soc. Civ. Eng., 97(IR3):343-353.
42
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55. Office of Water Resources Research. 1972. Agricultural runoff-
a bibliography. Water Resources Scientific Information Center,
PB-207514, 248p.
56. Reddick, H.E. and John G. Bamesburger. 1938. Erosion control on
steep irrigated slopes. Agr. Eng. 19:531.
57. Richardson, C.W. 1973. Runoff, erosion, and tillage efficiency
on graded-furrow and terraced watersheds. J. Soil arid Water
Conserv. 28:162-164.
58. Robinson, A.R. 1971. Sediment. J. Soil and Water Conserv.
26:18-19.
59. Romkens, M.J., D.M. Nelson, and J.V. Mannering. 1973. Nitrogen
and phosphorus composition of surface runoff as affected by
tillage method. J. Environ. Qual. 2:292-295.
60. Sakkas, J.G. and W.E. Hart. 1968. Irrigation with cut-back
furrow streams. J. Irrig. and Drain. Div., Proc. Amer. Soc.
Civ. Eng. 94(IR1):91-96.
61. Scofield, C.S. 1932. Steam pollution by irrigation residues.
J. Ind. Eng. Chem. 24:1223-1224.
62. Skogerboe, G.V. 1973. Agricultural impact on water quality in
western rivers. JLn Environmental Impact on Rivers, Hsich Wen
Shen (ed) ch. 12, p. 12-1 to 12-25.
63, Skogerboe, Gaylord V. and James P. Law, Jr. 1971. Research needs for
irrigation return flow quality control. Water Pollution Control
Research Series, Environmental Protection Agency, Project 13030,
98 p.
64. Skogerboe, Gaylord V., W.R. Walker, and J.E. Ayars. 1972. Modeling
water quality from agricultural lands. In Modeling of Water
Resource Systems, Volume II, A.K. Biswas, (ed.), p. 530-540.
65. Smith, J.H. and C.L. Douglas. 1973. Microbiological quality of
surface drainage water from three small irrigated watersheds
in southern Idaho, J. Environ. Qual. 2:110-112.
66. Sylvester, Robert 0. and R.W. Seabloom. 1963. Quality and signif-
icance of irrigation return flow. J. Irri. and Drain. Div.,
Proc. Amer. Soc. Civ. Engr. 89(IR3):l-27.
67, Sylvester, Robert 0. and Robert W. Seabloom. 1963. A study on the
character and significance of irrigation return flows in the
Yakima River Basin. Univ. of Wash., 103 p.
68, Tatorova-Krysteva, V.S. 1971. Erosion of some Bulgarian soils
by irrigation. Pochvovedeiye 12:107-115.
69. Taylor, C,A. 1940. Transportation of soil in irrigation furrows.
Agr. Eng. 21:307-309.
70. Taylor, C.A. 1935. Orchard tillage under straight furrow irriga-
tion Agr. Eng. 16:99-102.
71. Utah State University Foundation. 1969. Characteristics and pol-
lution problems of irrigation flow. USDI, Fed. Water Poll. Contr.
Adm., 237 p.
72. van Schilfgaarde, J., L. Bernstein, J.D. Rhoades, and S.L. Rawlins
1974. Irrigation management for salt control. J. Irrig. and Drain.
Div., Proc. Amer. Soc. Civ. Engr., 100 (IR3):321-328.
73. Vanoni, V.A. (ed.) 1975. Sedimentation Engineering. Amer. Soc.
of Civ, Eng., New York, N.Y.
43
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74. Viets, F.G., Jr. 1970. Soil use and water quality - a look to
the future. J. Agr. Food Chera, 18;789-792.
75. Wadleigh, Cecil H. 1968. Wastes in relation to agriculture and
forestry. USDA, Misc. Pub. No. 1065,
76. Watts, F.J., C.E. Brockway, and A.E. Oliver. 1974. Analysis
and design of settling basins for irrigation return flow. Idaho
Water Resources Institute, 74p,
77. Webb, H.J. 1962. Water pollution resulting from agricultural
activities. J. Amer. Water Works Assoc. 54:83-87.
78. Wells, D.M. and E.F. Gloyna. 1967. Estimating the effects of
return flows. J. Amer. Water Works Assoc., p. 805-819.
79. Westlake, W.E. 1966. Pesticides as contaminants of agricultural
waste waters. _In Agricultural Waste Waters, L.D. Doneen, (ed.)
Report No. 10, Water Resource Center, University .of Caliornia,
p. 90-93.
80. Wilke, O.C. 1973. Theoretical irrigation tailwater volumes.
J. Irrig. and Drain. Div., Proc. Amer. Soc, Civ. Eng., 99(1R3):
415-420.
81. Wilke, O.C. and E.T. Smerdon. 1969, A hydrodynamic determination
of cutback stream sizes or irrigation furrows. Trans. Amer. Soc.
Agr. Eng. 12:634-637.
82. Wright, C.C. 1928. Surface and subsurface waters of the Yakima
and Klamath projects. Wash. Agr. Expt. Sta. Bull. No. 228.
83. Wu, I.P. 1972. Recession flow in surface irrigation. J. Irrig. and
Drain. Div. Proc. Amer. Soc. Civ, Engr. 98(IR1):77-90.
84. Wu, I-Pai, and Tung Liang, 1970. Optimal design of furrow length
of surface irrigation. J. Irrig. and Drain. Div., Proc. Amer,
Soc. Civ. Engr., 96(IR3):319-332.
85. Yoo, Kyung H. 1974. Characteristics of nutrients and total solids
in irrigation return flows. Unpublished M.S. Thesis (Agr. Eng.)
University of Idaho.
86. Zimmerman, J.D. 1966. Irrigation. John Wiley and Sons, Inc.
New York.
44
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TECHNICAL REPORT DATA
:i'u.'ase read Instructions on the reverse before completing)
1, REPORT NO.
EPA-600/2-76-237
2.
3. RECIPIENT'S ACCESSIOf*NO.
4. TITLE AND SUBTITLE
CONTROL OF SEDIMENTS, NUTRIENTS, AND ADSORBED BIOCIDES
IN SURFACE IRRIGATION RETURN FLOWS
5. REPORT DATE
6. PERFORMING ORGANIZATION CODE
October 1976 (Issuing Date)
7. AUTHOR(S)
David L. Carter and James A. Bondurant
8. PERFORMING ORGANIZATION REPORT NO.
9 PERFORMING ORGANIZATION NAME AND ADDRESS
"U.S. Department of Agriculture
Agricultural Research Service, Western Region
Snake River Conservation Research Center
Kimberly, Idaho 83341
10. PROGRAM ELEMENT NO.
1HB617
11. CONTRACT/GRANT NO.
EPA-IAG-D5-F648
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Research and Development
Robert S. Kerr Environmental Research Laboratory
Ada. Oklahoma 74820
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA-ORD
15. SUPPLEMENTARY NOTES
16 ABSTRACT
The technology available for the control of sediments, nutrients, and adsorbed bio-
cides in surface irrigation return flows has been reviewed and evaluated. Some of
this technology could be applied immediately to reduce sediment and associated
nutrient and biocide concentrations in surface irrigation return flows. Much of the
available information needs to be integrated to develop improved control practices.
New ideas and new control technology are needed. Economic incentive programs are
needed to improve acceptance of control technology. The factors controlling erosion
and subsequent sediment concentrations in surface irrigation return flows, and how
these factors can be managed to reduce erosion and sediment concentrations are
reviewed and discussed. Three approaches (1) eliminating surface runoff, (2) reduc-
ing or eliminating erosion, and (3) removing sediments and associated nutrients and
biocides from surface irrigation return flows, and control measures for each approach
are discussed. Research and demonstration needs for improving and developing new
control technology are presented. These include simulation modeling of known erosion
parameters, the development of improved irrigation systems and methods, the design of
improved irrigation water distribution systems, and field management practices. The
need for more information on design and operational criteria for sediment retention
basins is discussed.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
COS AT I Field/Group
*Irrigation
*Soil conservation
*Pesticides
Management
Sediment control
Nutrient leaching
Irrigation return flows
02C
. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
53
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
45
U.S. GOVERNMENT HIMTING OFFICE: 1977-757-056/5*52 Re91on No. 5-11
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