DEM-GIS Based Spatially Distributed Storm Runoff Response Study Using Remotely-sensed Data

Abstract

The availability of spatial information from remote sensing, and the ability of geographicinformation system (GIS) to handle such data efficiently, have contributed much to the understandingof watershed runoff response and land cover changes. Distributed watershed models are commonlyused to investigate rainfall-runoff processes. These watershed models require topographic drainageinformation, such as watershed boundaries and drainage divides which can be derived from DigitalElevation Models (DEMs). Spatially distributed runoff was estimated for the Simms creek in the St.Johns River Water Management District (SJRWMD), Florida using the United States Department ofAgriculture, Natural Resources Conservation Service-Curve Number (USDA-NRCS-CN) method.Land use data from Digital Orthophoto Quarter Quadrangles (DOQQ) and Landsat EnhancedThematic Mapper Plus (ETM+) for 1990, 1995 and 2000 were used to estimate spatially distributedcurve numbers. A DEM-GIS based runoff routing technique based on 1-D kinematic wave flow wasmade to generate hydrographs based on travel time to the watershed outlet using spatiallydistributed data. Comparison was made between the observed and predicted runoff hydrographs andthree existing models: the Time-Area method, the Snyder unit hydrograph model and TOPMODEL, asemi-distributed saturation excess model using, 17 storm events from 1990, 1995, 1999 and 2000.The results indicate that the distributed travel time method can accurately predict runoff response forlarge isolated storms and the travel time approach performed better with higher efficiencies than theother two models. The Time-Area method performed better than the other models with averageefficiency of 0.7.