We combine long-term records from aerial photographs, detailed mapping using survey-grade GPS, and ground-based lidar with meteorological monitoring. Sand dune migration rates are currently about 35 meters per year.
Main page for National Hydrography Dataset (NHD), a comprehensive set of digital spatial data about surface water features, with links to references, data, software tools, applications, tutorials, technical support, and data maintenance.
Homepage for the National Land Cover Data (NLCD), a land cover classification scheme, for the United States based on data derived from Landsat Thematic Mapper satellite data. Includes links to description, products, accuracy, and program partners.
Portal to general information on the National Atlas of the United States with access for producing specialized maps and links to thematic maps including interactive maps, multimedia maps, map layers data warehouse, wall maps, and printable maps.