Significant Topographic Changes in the United States
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National Elevation Dataset (NED)
The NED, produced by the USGS, provides seamless coverage of the “best available” elevation data of the United States. The NED is a multiresolution dataset, with national coverage (except Alaska) available at 1-arc-second resolution (about 30 meters), while large portions of the country are available at 1/3-arc-second resolution (about 10 meters), and selected local and regional areas are available at 1/9-arc-second resolution (about 3 meters).
The source data for the NED primarily are the USGS 7.5-minute digital elevation models (DEMs) that are based on the USGS 1:24,000-scale topographic quadrangle maps. Nearly 55,000 of these quadrangle-based DEMs have been processed and assembled to produce the NED for the conterminous United States.
The NED is regularly updated on a bimonthly cycle that incorporates recent elevation data collections from both USGS and non-USGS sources so that the dataset reflects the best (publicly) available elevation data in an application-ready format.
The NED data used for this study are the 1-arc-second data available as of June 2003, which were produced entirely from USGS 30-meter and 10-meter resolution 7.5-minute DEMs. Thus, the NED derived from the standard USGS topographic map series represents the historical (prechange) dataset for multitemporal analysis. The figure below shows an overview of the NED used for this study.
Shaded relief portrayal of the National Elevation Dataset.
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://topochange.usgs.gov/ned.php
Page Contact Information: custserv@usgs.gov
Page Last Modified: August 20, 2008
