The National Map: USGS Hydro Cached Map Service - copy
收藏资源简介：
This service is a cached overlay of a cartographic representation of the National Hydrography Dataset (NHD). The NHD is a comprehensive set of digital geospatial data that encodes information about naturally occurring and constructed bodies of surface water, paths through which water flows, related features such as stream gages and dams, and additional hydrologic information. It is available nationwide in a 1:24,000-scale seamless dataset, referred to as high resolution NHD. The NHD supports many applications, such as making maps, geocoding observations, flow modeling, data maintenance and stewardship. For additional information, go to http://nhd.usgs.gov. Additional datasets are used for small-scale hydrography representation as well, including medium resolution NHDPlus published by EPA; USGS Small-Scale hydrography; and bathymetry from ETOPO1 Global Relief, provided by NOAA National Centers for Environmental Information, U.S. Coastal Relief Model.
