INVESTIGATING CATCHMENT HYDROLOGY AND LOW-FLOW CHARACTERISTICS USING GIS

The most frequent use of Geographic Information Systems (GIS) in hydro logy has been in input/output data handling for modeling purposes, as well as in the derivation of flow direction, flow length and slope map s from Digital Elevation Models (DEMs). In rum, these maps have been m erged with other maps, such as soils, land use, and vegetation maps to obtain flow velocities, isochrones, and Hydrologic Response Units (HR Us), This study presents examples of GIS applications to 1) create a d epression-less DEM from contour lines of terrain elevation 2) interpol ate groundwater heads based on head measurements at gee-referenced poi nts, 3) derive topographic catchments based on the DEM and derive grou ndwater contributing areas to given surface points based on interpolat ed head values, and 4) estimate streamflow characteristics based on to pographic catchments, groundwater contributing areas, and soil maps. O ur results indicate the usefulness of GIS applications in spatial hydr ologic analysis, interpolation, and prediction.