DEVELOPMENT OF A GEOGRAPHIC INFORMATION-SYSTEM FOR URBAN WATERSHED ANALYSIS

A geographic information system (GIS) interfaced with a distributed hy drologic model for urban watershed analysis. Basic data layers are dig itized into a spatial database, and the system topological data struct ures are used to generate feature attributes and data products necessa ry for modeling. Additional programming allows the system to use the c oordinate values of features in the watershed to directly calculate fl ow-plane geometry and routing distances of overland flow paths, gutter s, and storm sewer segments. Access to coordinate values in the covera ges also allows the system to automatically determine the connecting d rainage network, ol the order and direction of flow throughout the urb an drainage area. This is a significant improvement over other systems in which the order and direction of the network must be determined an d digitized by the user. The combined GIS/Modeling system is capable o f analyses of urban drainage problems at a variety of scales (inlet, b lock, basin) and at. a level of spatial detail not heretofore accompli shed.