Real-Time Watershed Delineation System Using Web-GIS

Abstract

A Web-based geographic information system (GIS) that can delineate watersheds in real time was developed for use in hydrologic analysis and to support hydrologic model operation on the Internet. The system integrates a watershed delineation (WD) engine, common gateway interfaces, a Web-GIS user interface, and supports digital spatial data including vector and grid formats. The WD program utilizes a double-seed array-replacement algorithm to obtain a watershed boundary from point coordinates. The system provides a user interface for the selection of an outlet point from a map display in the Web browser using MapServer Web-GIS capability. The WD and data extraction system has been implemented for all of Indiana, with extensive verification conducted in the 2,082.7 km2 Wildcat Creek watershed in Indiana. The time to obtain results and the quality of results are acceptable for use as a real-time system for WD via the Web.