U.S. Geological Survey --EROS Data Center

Delineation of Drainage Basins from 1 KM African Digital Elevation Data

Jeffrey J. Danielson,UNEP/GRID, EROS Data Center, Sioux Falls, SD 57198
e-mail: daniels @grid2.cr.usgs.gov

Abstract

Physical boundaries of drainage basins are critical for modeling of hydrologic processes in resource management, ecosystem analysis, and global change studies. A shortage of accurate drainage basin information, particularly outside the United States, has limited the application of hydrologic models and geographic information systems (GIS) in analyzing water-related issues.

At the U.S. Geological Survey's (USGS) EROS Data Center, the USGS, the National Aeronautics and Space Administration, the United Nations Environment Program, and others are developing 1 KM (30-arc second) resolution digital elevation models (DEMs) with global coverage to be completed by October 1996. Current GIS technologies provide a means to extract the drainage basins from the DEMs at a level of detail necessary to meet modeling objectives. North America was the first continent processed and Africa is now reaching completion.

Digital drainage basin data derived from 30-arc second DEMs are available for use in GIS and models, eliminating the need for map interpretation and digitizing. The hydrologic stream and watershed data may also be customized for specific databases by user specification of the outflow points for drainage delineation.