20240512 21263300 1.0 TRUE TRUE nhdplus The EPA contracted with Horizon Systems Corporation to create the NHDPlus. NHDPlus is an integrated suite of application-ready geospatial data products, incorporating many of the best features of the National Hydrography Dataset (NHD), the National Elevation Dataset (NED), and the National Watershed Boundary Dataset (WBD). NHDPlus includes a stream network based on the medium resolution NHD (1:100,000-scale), improved networking, feature naming, and “value-added attributes” (VAA). NHDPlus also includes elevation-derived catchments produced using a drainage enforcement technique first broadly applied in New England, and thus dubbed “The New-England Method.” This technique involves enforcing the 1:100,000-scale NHD drainage network by modifying the NED elevations to fit with the network via trenching and using the WBD to enforce hydrologic divides, and applying sinks in noncontributing areas. The resulting modified digital elevation model (DEM) was used to produce hydrologic derivatives that closely agree with the NHD and WBD. national hydrography dataset plus catchments Value added attributes attached to the US Geological Survey's NHD, as well as the features created to derive them. This layer contains only catchments. U.S. Geological Survey, U.S. Enviromental Protection Agency, Horizon Systems Corporation iVBORw0KGgoAAAANSUhEUgAAASwAAADICAYAAABS39xVAAAAAXNSR0IB2cksfwAAAAlwSFlzAAAO xAAADsQBlSsOGwAAAqpJREFUeJzt1DENADAMwLAd5U+5o7BvimQjyJXZ3T0AAfM7AOCVYQEZhgVk GBaQYVhAhmEBGYYFZBgWkGFYQIZhARmGBWQYFpBhWECGYQEZhgVkGBaQYVhAhmEBGYYFZBgWkGFY QIZhARmGBWQYFpBhWECGYQEZhgVkGBaQYVhAhmEBGYYFZBgWkGFYQIZhARmGBWQYFpBhWECGYQEZ hgVkGBaQYVhAhmEBGYYFZBgWkGFYQIZhARmGBWQYFpBhWECGYQEZhgVkGBaQYVhAhmEBGYYFZBgW kGFYQIZhARmGBWQYFpBhWECGYQEZhgVkGBaQYVhAhmEBGYYFZBgWkGFYQIZhARmGBWQYFpBhWECG YQEZhgVkGBaQYVhAhmEBGYYFZBgWkGFYQIZhARmGBWQYFpBhWECGYQEZhgVkGBaQYVhAhmEBGYYF ZBgWkGFYQIZhARmGBWQYFpBhWECGYQEZhgVkGBaQYVhAhmEBGYYFZBgWkGFYQIZhARmGBWQYFpBh WECGYQEZhgVkGBaQYVhAhmEBGYYFZBgWkGFYQIZhARmGBWQYFpBhWECGYQEZhgVkGBaQYVhAhmEB GYYFZBgWkGFYQIZhARmGBWQYFpBhWECGYQEZhgVkGBaQYVhAhmEBGYYFZBgWkGFYQIZhARmGBWQY FpBhWECGYQEZhgVkGBaQYVhAhmEBGYYFZBgWkGFYQIZhARmGBWQYFpBhWECGYQEZhgVkGBaQYVhA hmEBGYYFZBgWkGFYQIZhARmGBWQYFpBhWECGYQEZhgVkGBaQYVhAhmEBGYYFZBgWkGFYQIZhARmG BWQYFpBhWECGYQEZhgVkGBaQYVhAhmEBGYYFZBgWkGFYQIZhARmGBWQYFpBhWECGYQEZhgVkGBaQ YVhAhmEBGYYFnIoLreIHHblfYqUAAAAASUVORK5CYII=