A Digital Elevation Model (DEM) consists of a sampled array ofelevations for ground positions that are normally at regularly spaced intervals. The Digital Chart of the World (DCW) DEM data provide 30-by-30 arc-second digital elevation data produced from the Defense Mapping Agency's (DMA) 1:1,000,000-scale DCW contour and hydrology data. The EROS Data Center's DCW DEM project includes generation of 30 arc-second data for the entire world to be distributed on CD-ROM as major geographic regions are completed. As of May 1997, 30" DEM Grids for the whole are complete and available for distribution from the website given below.
Go to 30" DEM Web Site with descriptive data
Go back to Obtaining Hydrologic Data through the Internet