Urban Watershed Modeling Using Geographic Information System

A geographic information system (GIS) was constructed for an urban watershed in Baton Rouge, Louisiana, and used to direct a hydrologic modeling effort for water-shed management. All pertinent features were geocoded into the GIS and related attributes were stored in tables containing data relevant to hydrologic modeling. Watershed surfaces were represented by a triangular irregular network. The GIS identified hydrologic 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 discharge was routed using a standard kinematic wave model. System capabilities are demonstrated at the lot, polygon, block, and multiblock scales.