Significant Topographic Changes in the United States
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National Land Cover Dataset (NLCD)
The USGS has produced several national land cover products that are useful for assessing the landscape effects of human geomorphic activities. The National Land Cover Dataset (NLCD), which is derived from Landsat multispectral satellite data on a nominal 10-year mapping cycle, provides national coverage of basic land cover information at a 30-meter spatial resolution. The NLCD 1992 version was derived from early 1990s Landsat satellite remote sensing data. The mapping work for the NLCD 2001 version is based on early 2000s Landsat data.
The use of land cover data derived from remote sensing along with multitemporal elevation data allows for a more complete assessment of the geomorphic effects because land cover change often corresponds with the physical transformation of the land surface relief. The 1992 version of the NLCD, shown below, was used for this study.
The National Land Cover Dataset (1992 version).
Although the NLCD 2001 version has additional data layers (canopy density and impervious surfaces) that may have been useful for interpreting SRTM data, and the source dates are a close match to that of SRTM, the newer NLCD was not used because complete coverage for the conterminous United States was not available at the time of this study.
The Land Cover Status and Trends of the United States has also been used to help analyze the detected areas of topographic change. Spatially explicit land cover maps and corresponding land cover change products are produced for five dates between 1973 and 2000 for 10x10-kilometer sample blocks to derive regional land cover statistics. Both the sample block data and the regional summary statistics are useful for characterizing the relationships between land cover and topographic surface change.
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://topochange.usgs.gov/nlcd.php
Page Contact Information: custserv@usgs.gov
Page Last Modified: August 20, 2008
