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nwbd
National Watershed Boundary
Dataset (NWBD)
Federal agencies coordinating spatial water data have identified
the development of a National Watershed Boundaries Data
Set as a top priority for inclusion in the National Spatial
Data Infrastructure (NSDI).
The proposed NSDI Watershed Boundaries Data Set will have
the following key characteristics:
- Nationally consistent digital data set
- Nested subdivisions of established Cataloging Units
- 5-15 Watersheds per Cataloging Unit
- Boundaries based on 1:24,000-scale topographic maps
- Hydrologically based watersheds, not political divisions
- 10-digit Hydrologic Unit Codes
- Formally established watershed names
- Attribute information to identify all upstream and downstream
units
Where watershed boundaries have not already been mapped
using appropriate criteria, new watershed boundaries will
be developed using a semi-automated procedure based on elevation
data from the National Elevation Dataset. The boundaries
will be checked and edited using 1:24,000-scale Digital
Raster Graphics.
The National Watershed Boundaries Data Set, the National
Elevation Dataset, and National Hydrography Dataset inherently
are related. Early maintenance efforts will seek to identify
inconsistencies between these three data sets and use those
inconsistencies to help improve the quality of each national
data set.
For more information on the National Watershed Boundary
Dataset, see http://www.ftw.nrcs.usda.gov/huc_data.html
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