Abstract

A Schema and Delineation Method for a Drainage-Basin Geodatabase
Track: Water Resources
Authors: Jean Dupree

The basin boundary is a fundamental entity used in studies of surface-water resources and for planning water-related projects. Drainage-basin areas published by the U.S. Geological Survey (USGS) in annual Water Data Reports and in National Water Information System (NWIS) are still primarily based on hardcopy methods. The USGS Colorado Water Science Center developed a geodatabase schema and a basin-delineation method that uses the Watershed Boundary Dataset. This geodatabase includes three feature classes (point, line, and polygon) and four topology rules, which constrain interactions among line and polygon features. Of 217 newly delineated drainage basins, 24 had digital areas that differed by more than 3 percent from published NWIS dranage areas. Nearly all errors were in NWIS drainage-basin areas and were caused by the use of small-scale or poor-quality hardcopy maps. This schema and the delineation method are now used by two other USGS water science centers.