National Hydrography Dataset Plus (NHDPlus) is a national geospatial surface water framework. It is an integrated suite of application-ready geospatial data sets that incorporate many of the best features of the National Hydrography Dataset (NHD), the National Elevation Dataset (NED), and the Watershed Boundary Dataset (WBD). Geospatial analysts and modelers use this framework to support water resources applications. The United States Environmental Protection Agency (EPA) developed and maintains NHDPlus in partnership with the U.S. Geological Survey.
The Watershed Boundaries Download command of CivilGEO software allows the user to download EPA/USGS NHDPlus watershed (catchment) boundaries data from the USGS web map service as shapefile data, showing watershed boundary data on the Map View.
Note that this command works only within the United States.
Follow the steps below to download the watershed boundaries data:
- From the Map Data ribbon menu, select the Hydrography Data menu item, and then choose the Watershed Boundaries Download command.
- The Watershed Boundaries Download dialog box will be displayed.
The following sections describe how to interact with the above dialog box.
This section allows the user to specify the layer name and location to save the downloaded shapefile. By default, the Layer name is NHDPlus Catchment, which can be changed by the user. Click the […] button beside the Shapefile path entry to specify the directory location to save the downloaded GIS shapefiles.
NHDPlus Data Boundary Limits
This section allows the user to define the extent of watershed boundaries. The following options are available for defining the extent of watershed boundaries:
- Current screen limits: When this option is selected, the software will use the current extent of the Map View as a boundary limit for the NHDPlus map data to be downloaded.
- User-defined limits: When this option is selected, the user can click on the [Pick] button and draw a rectangular region on the Map View to define the boundary limits for the NHDPlus map data that is to be downloaded.
- Model extents: If a project model has been defined, this option will create a bounding rectangular region to correspond to the extents of the defined model, plus an additional buffer boundary.
Downloading Watershed Boundaries Data
Once all the options have been defined, click the [OK] button. The software will then look at each selected option and download the NHDPlus watershed data as shapefile data. The software will also display the data on the Map View as shown below.
After the NHDPlus watershed data has been downloaded, the software will then load the downloaded NHDPlus catchment data as a new layer in the Map Data Layers panel.
The user can also export the downloaded layers to CAD by right-clicking the layer name and then selecting the Export to CAD command from the displayed context menu.