&EPA
                                United States
                                Environmental Protection
                                Agency
                               Environmental Research
                               Laboratory
                               Athens GA30613
%i
                                Research and Development
                               EPA-600/S3-81-037 July 1981
Project Summary
                               Evaluation  of  Remote Sensing
                               Data  for  Input into
                               Hydrological  Simulation
                               Program-FORTRAIM (HSPF)
                               D. D. Franz and S. M. Lieu
                                 This report evaluates the feasibility
                               of using a remotely sensed database
                               as an input into the Hydrologic Simu-
                               lation Program - FORTRAN (HSPF).
                               Remotely sensed data from the
                               LANDSAT satellite and conventionally
                               obtained data were used to set up the
                               input parameters of HSPF. Simulations
                               were then run to compare the model
                               outputs from  the two sets of input
                               data.

                                 The remotely sensed data set per-
                               formed at least as well as the conven-
                               tional one when model results were
                               compared with observed data. Further,
                               the remotely sensed data set offered
                               savings estimated at 30 to 50 percent
                               in the cost of  set-up  and operation.
                               Areas of potential development of
                               remote sensing for modeling input are
                               suggested.

                                 The Image Based Information Sys-
                               tem (IBIS) used to manipulate the
                               LANDSAT data was found to contrib-
                               ute significantly to the data collection
                               and handling process.

                                 This Project  Summary was devel-
                               oped by EPA's Environmental Research
                               Laboratory, Athens, GA, to announce
                               key findings of the research project
                               that is fully documented in a separate
                               report of  the same title (see Project
                               Report ordering information at back).
                               Introduction
                                More and more frequently, planners
                               and scientists are turning to computer
                               modeling for assistance in understand-
                               ing the complexity of natural phenomena,
                               their interactions, and the impact of
                               human activities on the environment. To
                               successfully model  the complex and
                               subtle components of the environment,
                               many types of accurate data describing
                               large geographical areas are needed.
                               These data are essential to the con-
                               struction, execution, testing, and ulti-
                               mately, to the improvement of any
                               model. Available data, however, is not
                               always adequate. Tremendous potential
                               for improving the ease and accuracy of
                               modeling efforts lies in the development
                               of satellites able to remotely acquire a
                               wide variety of environmental data over
                               large areas of the  earth's surface.
                               Whether it .is feasible to use satellite
                               input into complex environmental models
                               is an area explored in this study.
                                Data from the LANDSAT satellite
                               were supplied by the  National Aeronau-
                               tics and Space Administration (NASA).
                               Terrestrially based data were provided
                               by the Northern Virginia Planning District
                               Commission (NVPDC). These data were
                               used as input in simulation runs with
                               the Hydrological Simulation Program -
                               FORTRAN (HSPF). The questions ad-
                               dressed include the feasibility of using
                               remotely sensed data as model input,
                               difficulties in the implementation of this

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approach, and the modeling accuracy
and cost effectiveness compared with a
conventional database. The contribu-
tion of ancillary computer hardware/
software  for handling LANDSAT infor-
mation to modeling, particularly the
Image Based Information System (IBIS),
is also assessed.

Conclusions
  Conclusions are drawn  for both the
results of the simulations themselves
and the  process  of use  of remotely
sensed databases  in HSPF modeling.
  In terms of the simulations themselves,
the remotely sensed database performed
at  least as well as the conventional
database. This is supported by the find-
ings below:
  • Differences in land-use distribu-
    tion (Broad Run of Occoquan Basin)
    had little effect on the overall out-
    come  of HSPF modeling. The
    changes in parameters resulting
    from differing land use distributions
    tended to balance  out during
    simulation.
  • Both the conventional and the
    remotely sensed parameter sets
    performed well for certain simu-
    lations. The results for flow rate,
    water temperature, and dissolved
    oxygen are comparable to observed
    data.
  • Neither parameter  set seemed  to
    perform well in nutrient simula-
    tions. Assessing the accuracy  of
    these results, however, was diffi-
    cult because of inadequacies in the
    observed  data and the modeling
    approach.
  • Overall, the parameter set from the
    remotely sensed database per-
    formed at least as  well as the
    conventional set. Remote sensing
    also offered some  additional ad-
    vantages.
  • Refinement of information on urban
    and  water areas in the remotely
    sensed land-use classification
    would result in better segment
    definition.
  Conclusions concerning the use of a
remotely sensed database with IBIS are:
  • The current use of remotely sensed
    information is relatively indirect:
    classes of land use are processed
    by a transformation function  to
    generate modeling parameters.
    With the availability of the appro-
    priate  transformation function(s),
    the use of remotely sensed data-
    bases for HSPF and other types of
    modeling is feasible.
  • Use of a remotely sensed database
    offers significant savings in cost
    (about 30 to 50 percent) in com-
    parison with use of a conventional
    database. Larger study areas should
    provide even greater economic
    advantages.
  • A remotely sensed database offers
    advantages of repeatability, relative
    rapidity and ease of information
    collection. It would be particularly
    advantageous in  large or inacces-
    sible areas or in areas requiring
    frequent database updates.
  • IBIS made significant contributions
    in verifying segment definition and
    in  computing basin wide average
    parameters and other cross tabula-
    tions, which greatly enhanced the
    use of the remotely  sensed data-
    base. The image formatted data
    plane concept of IBIS is vital to the
    integration of various sources and
    types of data, particularly on a large
    scale.

Recommendations
  Recommendations for further use of
remote sensing in hydrologic and water
quality simulations include:
  • Additional development of the data
    collection and transformation
    processes. Because its lack  is the
    main impediment to more intensive
    and extensive use of remote sens-
    ing, further development and gei
    eralization of transformatic
    processes is needed.
  • Refinement of the remotely senst
    land-use classification of urba
    areas. This would enhance the us
    of satellite information  in areas <
    rapid urban development, wher
    updates are required to accurate
    assess changes in hydrology an
    water quality.
  • Use of remotely sensed database
    for modeling agricultural or unde
    veloped areas, particularly if thes
    are large or inaccessible.
  • Assessment of information the
    can be obtained for modeling pui
    poses from future satellite deve
    opments. In long-range terms, thi
    is a  valuable avenue of researc
    because the availability of nev
    data  may significantly affect o
    even  entirely modify the modelini
    approach.
  The utilization of IBIS occurred sub
sequent to the initiation of the curren
effort. A more comprehensive evalua
tion of the use of HSPF and remoti
sensing,  particularly with the use o
IBIS, could be conducted on a signifi
cantly larger area. In conjunction, it i:
recommended that the digital terrair
data from the Defense Mapping Agenq
(DMA) be utilized to improve basin slop*
determinations.
   D. D. Franz andS. M. Lieu are with Hydrocomp, Inc., Mountain View, CA 94040.
   T. O. Barnwell is the EPA Project Officer (see below).
   The complete report, entitled 'Evaluation of Remote Sensing Data for Input into
     Hydrological Simulation Program-FORTRAN (HSPF)." (Order No. PB 81 -209 561;
     Cost: $11.00, subject to change) will be available only from:
           National Technical Information Service
           5285 Port Royal Road
           Springfield,  VA 22161
           Telephone: 703-487-4650
   The EPA Project Officer can be contacted at:
           Environmental Research Laboratory
           U.S. Environmental Protection Agency
           Athens, GA 30613
                                                                                     •> US. GOVERNMENT PRINTING OFFICE. 1M1 -757-OU/7ZZ4

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