This layer is extracted from The High Resolution National Hydrography Dataset Plus (NHDPlus HR). This is an integrated set of geospatial data layers, including the best available National Hydrography Dataset (NHD), the 10-meter 3D Elevation Program Digital Elevation Model (3DEP DEM), and the National Watershed Boundary Dataset (WBD). The NHDPlus HR combines the NHD, 3DEP DEMs, and WBD to create a stream network with linear referencing, feature naming, "value added attributes" (VAAs), elevation-derived catchments, and other features for hydrologic data analysis.

The National Hydrography Dataset (NHD) is a feature-based database that interconnects and uniquely identifies the stream segments or reaches that make up the nation's surface water drainage system. NHD data was originally developed at 1:100,000 scale and exists at that scale for the whole country. High resolution NHD adds detail to the original 1:100,000-scale NHD. (Data for Alaska, Puerto Rico and the Virgin Islands was developed at high-resolution, not 1:100,000 scale.) Like the 1:100,000-scale NHD, high resolution NHD contains reach codes for networked features and isolated lakes, flow direction, names, stream level, and centerline representations for areal water bodies. Reaches are also defined to represent waterbodies and the approximate shorelines of the Great Lakes, the Atlantic and Pacific Oceans and the Gulf of Mexico. The NHD also incorporates the National Spatial Data Infrastructure framework criteria set out by the Federal Geographic Data Committee.

The National Hydrography Dataset (NHD) is a feature-based database that interconnects and uniquely identifies the stream segments or reaches that make up the nation's surface water drainage system. NHD data was originally developed at 1:100,000 scale and exists at that scale for the whole country. High resolution NHD adds detail to the original 1:100,000-scale NHD. (Data for Alaska, Puerto Rico and the Virgin Islands was developed at high-resolution, not 1:100,000 scale.) Like the 1:100,000-scale NHD, high resolution NHD contains reach codes for networked features and isolated lakes, flow direction, names, stream level, and centerline representations for areal water bodies. Reaches are also defined to represent waterbodies and the approximate shorelines of the Great Lakes, the Atlantic and Pacific Oceans and the Gulf of Mexico. The NHD also incorporates the National Spatial Data Infrastructure framework criteria set out by the Federal Geographic Data Committee.

This tabular data set represents average topgraphic wetness index compiled for two spatial components of the NHDPlus version 2 data suite (NHDPlusv2) for the conterminous United States; 1) individual reach catchments and 2) reach catchments accumulated upstream through the river network. This dataset can be linked to the NHDPlus version 2 data suite by the unique identifier COMID. The Topgraphic Wetness Index is a steady state index that’s used to predict areas susceptible to saturated land surfaces and areas that carry the potential to produce overland flow. The index is represented by ln (a/tan(beta)), where ln is the Napierian logarithm, a is the upslope area per unit contour length, and tan/(beta) is the slope gradient (Wolock and McCabe, 1995). The source data for average topgraphic wetness index used here was produced by David Wolock (United States Geological Survey, written communic., 2012). Units are ln(m); where ln(m) = the Naperian logarithm of length, where length is measured in meters. Reach catchment information characterizes data at the local scale. Reach catchments accumulated upstream through the river network characterizes cumulative upstream conditions. Network-accumulated values are computed using two methods, 1) divergence-routed and 2) total cumulative drainage area. Both approaches use a modified routing database to navigate the NHDPlus reach network to aggregate (accumulate) the metrics derived from the reach catchment scale. (Schwarz and Wieczorek, 2018).

This tabular data set represents average topgraphic wetness index compiled for two spatial components of the NHDPlus version 2 data suite (NHDPlusv2) for the conterminous United States; 1) individual reach catchments and 2) reach catchments accumulated upstream through the river network. This dataset can be linked to the NHDPlus version 2 data suite by the unique identifier COMID. The Topgraphic Wetness Index is a steady state index that’s used to predict areas susceptible to saturated land surfaces and areas that carry the potential to produce overland flow. The index is represented by ln (a/tan(beta)), where ln is the Napierian logarithm, a is the upslope area per unit contour length, and tan/(beta) is the slope gradient (Wolock and McCabe, 1995). The source data for average topgraphic wetness index used here was produced by David Wolock (United States Geological Survey, written communic., 2012). Units are ln(m); where ln(m) = the Naperian logarithm of length, where length is measured in meters. Reach catchment information characterizes data at the local scale. Reach catchments accumulated upstream through the river network characterizes cumulative upstream conditions. Network-accumulated values are computed using two methods, 1) divergence-routed and 2) total cumulative drainage area. Both approaches use a modified routing database to navigate the NHDPlus reach network to aggregate (accumulate) the metrics derived from the reach catchment scale. (Schwarz and Wieczorek, 2018).

This tabular data set represents the percent of Hydrologic Landscape Regions compiled for two spatial components of the NHDPlus version 2 data suite (NHDPlusv2) for the conterminous United States; 1) individual reach catchments and 2) reach catchments accumulated upstream through the river network. This dataset can be linked to the NHDPlus version 2 data suite by the unique identifier COMID. The source data is the "Hydrologic landscape regions of the United States" produced by the United States Geological Survey (Wolock, 2003). Units are percent. The "Hydrologic landscape regions of the United States" are a 20-class classification scheme of noncontiguous regions (HLRs) built on the basis of similarities in land-surface form, geologic texture, and climate characteristics (Wolock, 2003). Reach catchment information characterizes data at the local scale. Reach catchments accumulated upstream through the river network characterizes cumulative upstream conditions. Network-accumulated values are computed using two methods, 1) divergence-routed and 2) total cumulative drainage area. Both approaches use a modified routing database to navigate the NHDPlus reach network to aggregate (accumulate) the metrics derived from the reach catchment scale. (Schwarz and Wieczorek, 2018).

This tabular data set represents the percent of Hydrologic Landscape Regions compiled for two spatial components of the NHDPlus version 2 data suite (NHDPlusv2) for the conterminous United States; 1) individual reach catchments and 2) reach catchments accumulated upstream through the river network. This dataset can be linked to the NHDPlus version 2 data suite by the unique identifier COMID. The source data is the "Hydrologic landscape regions of the United States" produced by the United States Geological Survey (Wolock, 2003). Units are percent. The "Hydrologic landscape regions of the United States" are a 20-class classification scheme of noncontiguous regions (HLRs) built on the basis of similarities in land-surface form, geologic texture, and climate characteristics (Wolock, 2003). Reach catchment information characterizes data at the local scale. Reach catchments accumulated upstream through the river network characterizes cumulative upstream conditions. Network-accumulated values are computed using two methods, 1) divergence-routed and 2) total cumulative drainage area. Both approaches use a modified routing database to navigate the NHDPlus reach network to aggregate (accumulate) the metrics derived from the reach catchment scale. (Schwarz and Wieczorek, 2018).

This dataset contains the initial 3D Hydrography Program (3DHP) flow network topology, which is based on the final High Resolution National Hydrography Dataset (NHD), and a set of mainstem river identifiers based on the Medium resolution NHDPlus Version 2 (NHDPlusV2). The 3DHP flow network topology and mainstem identifiers contained in this data release add two key pieces of information to the flow table of the National Hydrography Dataset: 1) at every junction, one and only one main upstream and downstream connection has been identified 2) every "in network" flowline has been assigned a mainstem identifier that places it into a hierarchy of rivers and drainage basins. For description of 1 and 2 and additional background, see supplemental information. Files included: - HU6_mainstem_outlets.geojson Outlet locations of six-digit hydrologic units along mainstem network. - nhd_3dhp_conus_mainstems.zip Zipped table in Comma Separated Values (csv) format containing NHD permanent identifiers and mainstem Uniform Resource Identifiers (URIs) for the Contiguous United States (CONUS). - nhd_3dhp_conus_flownetwork.zip Zipped csv table containing from / to NHD permanent identifiers (from flowline to flowline) and upmain / downmain attributes for CONUS. - nhd_3dhp_conus_vpu_membership.zip Zipped csv table containing NHD permanent identifiers and which Vector Processing Unit (VPU) they belong in. - nhd_3dhp_oconus_mainstems.zip Zipped csv table containing NHD permanent identifiers and mainstem URIs for areas Outside of the Contiguous United States (OCONUS). - nhd_3dhp_oconus_flownetwork.zip Zipped csv table containing from / to NHD permanent identifiers (from flowline to flowline) and upmain / downmain attributes for OCONUS. -3dhp_flownetwork.zip Zipped csv table containing from / to 3DHP identifiers (from flowline to flowline) and upmain / downmain attributes. - nhd_3dhp_nonnetwork_mainstems.zip Zipped csv table containing mainstem identifiers for features not included in the NHD flow table. - nhd_final_registry.zip Zipped csv table containing all expected flowlines from the final NHD -- excludes geometry. - nhd_reachcode_mainstem.zip Zipped csv table containing a mapping between mainstem identifiers and NHD reachcodes. - nhd_3dhp_region_connections.zip Zipped csv table containing connections between vector processing unit regions defined by four-digit hydrologic unit. - nhd_3dhp_mainstem_summary.zip Zipped csv table containing summary information about mainstems contained in nhd_3dhp_conus_mainstems.zip and nhd_3dhp_oconus_mainstems.zip.