WBD v2.3.1 Model Poster 12202021

The Watershed Boundary Dataset (WBD) is a seamless national hydrologic unit geospatial dataset. The WBD is mapped and managed by the U.S. Geological Survey and is an OMB-A16 National Geospatial Data Asset. WBD data stewards have been instrumental in providing information on local hydrologic conditions.

Hydrologic units represent the area of the landscape that drains to a portion of the stream network. Hydrologic unit boundaries in the WBD are determined based on topographic, hydrologic, and other relevant landscape characteristics. The hydrologic units (HUs) in the WBD form a standardized system for organizing, collecting, managing, and reporting hydrologic information for the Nation. The HUs in the WBD are arranged in a nested, hierarchical system with each HU in the system identified using a unique code.

The WBD seamlessly represents hydrologic units at six required and two optional hierarchical levels. Hydrologic unit codes (HUC) are developed using a progressive two-digit system where each successively smaller areal unit is identified by adding two digits to the identifying code the smaller unit is nested within. WBD contains eight levels of progressive hydrologic units identified by unique 2-to 16-digit codes. The dataset is complete for the United States to the 12-digit hydrologic unit. The 14-and 16-digit hydrologic units are optional and are not complete for the Nation.

This poster provides details on the WBD Data Model v2.3.1 geodatabase and its polygon and line feature datasets and tables. Each HU level is mapped in a separate polygon feature class. The WBD contains drainage area features for select National Water Information System (NWIS) gages contained within line and polygon feature datasets. Feature attributes and their properties are provided for each component dataset. Attributes with elements limited to a domain include details on the range of values and their constraints.