TNM data (elevation and land cover) have been used to develop a national inventory of significant topographic changes in the U.S. TNM elevation data (National Elevation Dataset) and Shuttle Radar Topography Mission (SRTM) data form a unique pair of seamless multi-temporal elevation datasets that were analyzed to detect 20th century topographic surface changes. An extensive Web site ( http://topochange.cr.usgs.gov/ ) details the project. An interactive viewer ( http://topochange.cr.usgs.gov/TopoChange_viewer/viewer.htm ) allows viewing, query, and download of the topographic change inventory and selected TNM layers.
Voting on Ideas
Vote for your favorite ideas by clicking on the up arrow.To undo an upvote, simply click the arrow again. This second click removes your vote.