Stormflow simulation using a geographical information system with a distributed approach

With the increasing availability of digital and remotely sensed data such a s land use, soil texture, and digital elevation models (DEMs), geographic i nformation systems (GIS) have become an indispensable tool in preprocessing data sets for watershed hydrologic modeling and post processing simulation results. However, model inputs and outputs must be transferred between the model and the GIS. These transfers can be greatly simplified by incorporat ing the model itself into the GIS environment. To this end, a simple hydrol ogic model, which incorporates the curve number method of rainfall-runoff p artitioning, the ground-water baseflow routine, and the Muskingum flow rout ing procedure, was implemented on the GIS. The model interfaces directly wi th stream network, flow direction, and watershed boundary data generated us ing standard GIS terrain analysis tools; and while the model is running, va rious data layers may be viewed at each time step using the full display ca pabilities. The terrain analysis tools were first used to delineate the dra inage basins and stream networks for the Susquehanna River. Then the model was used to simulate the hydrologic response of the Upper West Branch of th e Susquehanna to two different storms. The simulated streamflow hydrographs compare well with the observed hydrographs at the basin outlet.