&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 ------- 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 ------- ^ Postage and United States Center for Environmental Research pees pajQ< Environmental Protection Information Environmental Agency Cincinnati OH 45268 Protection Agency EPA 335 Official Business Penalty for Private Use $300 PS 0000329 AGENCY ------- |