A geographi information system (gis) was developed as a practical tool to streamline some of the operational problems faced by manyagencies dealing with hydrologic analysis. Conventional manual analysis requires significant time and expertise. The expert system developed will automatically generate the drainage area and streamflow hydrograph for a watershed. The system is made feasible by using digital data that are available commercially for the entire united states. The data bases developed contain gridded elevation values and stream location coordinates. The software developed integrates the digital data with some unique terrain analysis techniques and fundamental hydrologic methods. The only user input required is the outlet location of the watershed. Internally, the program creates a gridded network of flow paths across the basin. By analysis of this gridded network, the drainage area and hydrologic information are defined. Thesystem was tested on a variety of basins and compared with some standard manual methods. The geographic information system was able to reproduce the manual methods with tremendous savings of time and cost. Overall, the system is a practical tool for any agency that must consider hydrologic analysis of many areas. This paper appears in transportation research record no. 1261, Geographic information systems 1990.
Abstract