U.S. Geological Survey --EROS Data Center
The map below displays a gray relief of the flow direction grid for the 1 KM African DEM. The boxed in region identifies the Congo-Zaire flow channels and displays the complex amount of information that can be extracted from the DEM. The movement of water across the land surface is called runoff. The directions runoff flows across a DEM surface is called flow directions. The flow directions are determined by finding the steepest descent from each cell in the DEM. The distance and direction of descent is calculated by using the eight neighborhood process (ESRI, 1992) adapted from Jenson and Domingue (1988). Once flow directions are developed, basin delineation can be accomplished.
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