NHDPlus (National Hydrography Dataset Plus)
NHDPlus is a suite of geospatial products that build upon and extend the capabilities of the National Hydrography Dataset (NHD), the National Elevation Dataset (NED) and the Watershed Boundary Dataset (WBD). Interest in estimating stream flow volume and velocity to support pollutant dilution (fate-and-transport) modeling was the driver behind the joint U.S. Environmental Protection Agency and U.S. Geological Survey effort to develop NHDPlus.
Since NHDPlus is produced from static snapshots of the NHD, NED and WBD, it includes the features and capabilities of these ingredient datasets. NHDPlus integrates the vector NHD stream network and WBD hydrologic unit boundaries with the NED gridded land surface. This hydrologically-conditioned surface enables the delineation of a catchment (local drainage areas) for each NHD stream segment. The catchments are used to associate precipitation, temperature and runoff data with each stream segment for estimating NHDPlus stream flow.
Elevations along each stream are used to compute stream slope for estimating NHDPlus velocities used in time of travel analyses. In addition to stream flow and velocity, NHDPlus provides additional value-added attributes, including stream order and a group of attributes that facilitate rapid stream network traversal and query. NHDPlus catchments are used to associate other landscape attributes, such as land cover, with stream segments.
These capabilities enable a diverse collection of water-related applications implemented by a large and growing user community. The widespread positive response to initial NHDPlus Version 1 (NHDPlusV1), released in 2006, prompted the multi-agency NHDPlus team to design an enhanced NHDPlus Version 2 (NHDPlusV2) that was released in 2012.
Since the significantly improved NHDPlusV2 is intended to supercede NHDPlusV1, new and existing NHDPlus users are strongly encouraged to use NHDPlusV2. While the NHDPlusV1 data, metadata and documentation remains available from this site, user support for the NHDPlusV1 will be increasingly limited. The NHDPlusV2 User Guide (PDF)(182 pp, 4.4 MB, About PDF) describes the differences between the two versions.