NHDPlus High Resolution: A National Map of Where Water Flows

By Susan G. Buto and Rebecca D. Anderson

Floodwaters surround houses in Craven County, North Carolina. Jocelyn Augustino, Federal Emergency Management Agency.

Why the Nation needs one

Fresh water keeps communities and ecosystems healthy and is critical to agriculture, industry and commerce — and it is increasingly strained by demand and by natural and human-caused events. Too much water in the wrong place is a problem too: in 2019 alone, flooding in the Missouri, Arkansas and Mississippi River basins cost a combined $20 billion (Smith, 2020).

The models and decision tools used to predict risk and respond to impacts on water resources depend on accurate, high-resolution maps of the Nation's waters. They need to know where the water is, and how it relates to things beyond the stream network — forests, cities and infrastructure. That takes an up-to-date, high-resolution national hydrography framework.

From NHDPlus to NHDPlus HR

How it is built

The three datasets NHDPlus HR integrates. Karen Adkins, USGS.

NHDPlus HR integrates three national datasets into a suite of vector, raster and tabular data:

• the high-resolution National Hydrography Dataset (NHD);
• the Watershed Boundary Dataset (WBD);
• the 3D Elevation Program (3DEP) 10-meter digital elevation model (DEM).

What users get:

• Snapshots of the NHD, WBD and DEM data it was built from.
• An elevation-based catchment (drainage area) for every flowline in the stream network, as raster and vector.
• Elevation-based flow direction and flow accumulation rasters, with the elevation data used to calculate them.
• Tables of value-added attributes for navigating, analyzing and displaying the network.

Value-added attributes

The value-added attributes (VAAs) extend what the core NHD network can do:

• hydrologic sequencing;
• stream order;
• cumulative drainage area;
• flow withdrawals, transfers and augmentation;
• elevations and slopes of flowlines;
• mean annual flow and velocity estimates for each flowline.

Details: VAA web page.

Catchments: the local drainage areas

Alongside the NHD's stream network and addressing and the WBD's hydrologic units for reporting, NHDPlus HR adds a seamless fabric of local drainage areas, known as catchments — one for each confluence-to-confluence stream segment.

Elevation-derived catchments, in color, one for each stream segment in a drainage area. Karen Adkins, USGS.

Linking landscape data — precipitation, temperature, runoff — to each segment through its catchment makes it possible to:

• estimate streamflow;
• evaluate the landscape's effects on aquatic habitats;
• predict floods;
• estimate water quality in ungaged streams.

What it is used for

• StreamStats, a USGS program of regression-based streamflow statistics — peak flows for designing bridges and culverts, and low flows for studying biological resources in droughts (Ries and others, 2017).
• Water-quality models such as SPARROW (SPAtially Referenced Regression On Watershed attributes). Once NHDPlus HR is complete nationally, it will give them a consistent framework for understanding water quality and contaminant transport in the Nation's streams.
• The National Water Model, which simulates streamflow volume and velocity over the entire continental United States so forecasters can predict when and where flooding can be expected. NHDPlus HR will provide its hydrography base.

National Water Model streamflow simulation for April 23, 2019. NOAA.

Scaling the map: the VisibilityFilter

The VisibilityFilter attribute lets users prune the stream network to show the features that suit each of eight map scales, while the underlying geometry stays intact.

• Available in all NHD staged products for the conterminous United States, and in a limited subset of the NHDPlus HR Beta datasets.
• Coming to all updated NHDPlus HR data.

More: VisibilityFilter web page.

Local knowledge needed

Anyone can submit corrections or improvements to the NHD, WBD and NHDPlus HR through the USGS web-based Markup Application — see National Hydrography Tools, or email nhd@usgs.gov. More about NHDPlus HR: usgs.gov/NatHydro.

Sources

Based on NHDPlus High Resolution (NHDPlus HR)—A Hydrography Framework for the Nation, by Susan G. Buto and Rebecca D. Anderson, USGS Fact Sheet 2020–3033, U.S. Geological Survey; a work of the United States government in the public domain. The photograph and graphics are taken from the fact sheet's PDF, which the import had left out: the floodwaters by Jocelyn Augustino, FEMA; the NHDPlus HR and catchment graphics by Karen Adkins, USGS; the National Water Model graphic by NOAA.