URBAN WATERSHED MODELING USING GEOGRAPHIC INFORMATION-SYSTEM

A geographic information system (GIS) was constructed for an urban wat ershed in Baton Rouge, Louisiana, and used to direct a hydrologic mode ling effort for water-shed management. All pertinent features were geo coded into the GIS and related attributes were stored in tables contai ning data relevant to hydrologic modeling. Watershed surfaces were rep resented by a triangular irregular network. The GIS identified hydrolo gic response units (HRUs), and the locational information (coordinates ) of the HRU boundaries were used in conjunction with the coordinates of the nodes of the storm drain system to guide and direct the model. The locational data were also used to determine dimensions of the HRU as well as all flow lengths (both overland and storm drain). The curve number method was used to determine rainfall excess, and the discharg e was routed using a standard kinematic wave model. System capabilitie s are demonstrated at the lot, polygon, block, and multiblock scales.