The NHD-Plus project was initiated by EPA and USGS to facilitate consistent national and interstate stream assessments. The NHD-Plus hydrography layer provides a unique spatial code for each stream reach within the U.S. and is used for a rapidly growing number of applications. Some advanced user groups have developed databases comprised of reach-scale descriptors (e.g., elevation, slope, drainage area, etc.). Hundreds of those descriptors now exist and can be used with the NHD-Plus and NSI networks as predictor variables in stream analyses. Brief descriptions of those databases and hyperlinks to relevant websites or contact persons knowledgeable about accessing the data are given below. Users are responsible for assessing the utility of these databases and should conduct a thorough review of all metadata and any associated publications prior to their use in analysis. If you are part of a group that has developed a significant database of reach descriptors available on a website and would like to have it described on this website, please contact us regarding the possibility.
1. NHDPlus “Value-added attributes” (VAA). The NHD-Plus stream network includes VAAs that are useful descriptors for all stream reaches in the conterminous U.S. Examples include elevation, slope, cumulative drainage area, land cover, temperature, precipitation, stream order, mean annual flow, and water velocity. The data and metadata for VAAs are distributed through the NHD-Plus website. Details are provided in an extensive NHD-Plus user guide. For additional questions about NHD-Plus, email NHD-Plus support (email@example.com).
2. StreamCat (Stream-Catchment) dataset contains >100 variables for predicting aquatic condition and watershed integrity in ~2.7 million watersheds within the conterminous USA. These variables include both natural (e.g., climate, soils, geology) and anthropogenic (e.g., dams, agriculture, urbanization) factors and were derived for use with NHD-Plus v.2 to enable stream-based studies. The StreamCat framework used topological flow information contained within the NHDPlusV2 to summarize upstream characteristics for each NHD-Plus stream reach. For more information, visit the project website or contact Marc Weber (Weber.Marc@epa.gov), Scott Leibowitz (Leibowitz.Scott@epa.gov), Tony Olsen (Olsen.Tony@epa.gov), Darren Thornbrugh (Thornbrugh.Darren@epa.gov), or Ryan Hill (firstname.lastname@example.org).
3. The National Fish Habitat Partnership (NFHP) data system makes available data generated through the National Assessment efforts, as well as region-specific data provided by Fish Habitat Partnerships and regional data from NFHP cooperators. Many of those datasets are linked directly to NHD-Plus and can be viewed dynamically using the NFHP Data Catalog, which allows filtering, visualization, and download of data from a single location. For additional information about the NFHP Data System, please contact Daniel Wieferich (303-202-4594; email@example.com). For additional information about the Science and Data within NFHP, please contact one of the Science and Data Committee Co-Chairs, Gary Whelan (517-373-6948; firstname.lastname@example.org) or Peter Ruhl (703-648-6841; email@example.com).
4. Base-Flow Index (BFI) data for the conterminous United States. Base flow is the component of streamflow that can be attributed to ground-water discharge into streams. This 1-kilometer raster (grid) dataset for the conterminous United States was created by interpolating base-flow index BFI values estimated at U.S. Geological Survey (USGS) streamgages. For additional information contact David Wolock (firstname.lastname@example.org; (785) 832-3528).
5. Wall-to-Wall Anthropogenic Land Use Trends (NWALT) for the conterminous U.S., 1974–2012. This dataset provides a national 60-meter, 19-class mapping of anthropogenic land uses for five time periods from 1974 to 2012. The dataset is based on a slightly modified version of the National Land Cover Database 2011 (NLCD 2011) that was recoded to a schema of land uses, and mapped back in time to develop datasets for earlier eras. The work was completed as part of the USGS National Water-Quality Assessment (NAWQA) Program. For additional information, visit the project website or contact Lori Sprague (303-236-6921; email@example.com) or Peter Ruhl (firstname.lastname@example.org; 703-648-6841).
6. The Valley Bottom Confinement database is a GIS based polygon layer that shows unconfined valley bottoms for portions of the Northwestern U.S. The valley confinement algorithm (VCA) used USGS 30 m DEM data and NHDPlusV2 flowline data to model unconfined valley bottoms at a scale of approximately 1:50,000 to 1:100,000. The algorithm used a valley “flooding” technique to identify flat valley bottoms greater than approximately 60-90 m in width. The data were generated for U.S. Forest Service lands in the Interior Columbia Basin (Region 17 of the Watershed Boundary Dataset) and the northwestern portion of Missouri Region 10. The VCA and resultant data are fully described in the Forest Service publication, RMRS-GTR-321. For more information, please visit the project website or contact Dave Nagel (email@example.com; 208-373-4397).
7. The Western U.S. Flow Metrics database provides a consistent set of flow metrics at reach-scale resolution throughout of the western U.S. based on daily simulations from the Variable Infiltration Capacity (VIC) macroscale hydrologic model produced by the University of Washington Climate Impacts Group. Trout Unlimited and the U.S. Forest Service Rocky Mountain Research Station used VIC outputs to create a set of ecologically relevant flow metrics that are easily linked to the NHD-Plus layer. Flow metrics are available for a historical period and two future climate periods associated with three global climate model ensembles. The data and metadata are distributed through the project website. For more details, please visit the project website or contact Charlie Luce (firstname.lastname@example.org; 208-373-4382) or Dave Nagel (email@example.com; 208-373-4397).
8. The NorWeST (Northwest Stream Temperature) temperature scenario database provides a consistent set of modeled August mean temperatures at 1-kilometer resolution throughout >800,000 stream kilometers in the western U.S. Thirty historical and future temperature scenarios are available that were developed from a SSN model fit to data measured at >20,000 unique stream sites. Scenarios are available as ArcGIS files that are compatible with the NHD-Plus layer. The data and metadata are openly distributed through the NorWeST website. For more details, please visit the website or contact Dave Nagel (firstname.lastname@example.org; 208-373-4397) or Dan Isaak (email@example.com; 208-373-4385).
9. Air temperatures and other climate variables for historic and future scenarios from the USGS Regional Climate Downscaling website. Data are dynamically downscaled using the RegCM3 climate model to 4-kilometer and 15-kilometer grids that encompass most of North America. The data and metadata are openly distributed through the website; for more details, contact Steve Hostetler (firstname.lastname@example.org) or Jay Alder (email@example.com).