Watershed delineation using the National Elevation Dataset and semiautomated techniques

Federal, State, and local agencies have realized that currently available hydrologic units are not of sufficient scale for many applications. An interagency effort is under way to subdivide hydrologic units into smaller units called watersheds and subwatersheds. The National Elevation Dataset contains the best available elevation data merged into a seamless database for the entire United States. These data can be readily used to delineate watershed and subwatershed basins. Recently developed ArcView tools facilitate the semiautomatic delineation of watersheds and subwatersheds.