Contents
- 1 Is the watershed boundary dataset in the public domain?
- 2 What makes up a watershed in North America?
- 3 Is the hydrologic dataset complete for the United States?
- 4 How are hydrologic unit boundaries determined in the WBD?
- 5 How to access the USGS hydrography datasets?
- 6 How is delineation used in the watershed segmentation process?
Is the watershed boundary dataset in the public domain?
(Public domain.) The Watershed Boundary Dataset (WBD) is a seamless, national hydrologic unit dataset. Simply put, hydrologic units represent the area of the landscape that drains to a portion of the stream network.
What makes up a watershed in North America?
(Public domain.) Watershed map of North America showing 2-digit hydrologic units. A watershed is an area of land that drains all the streams and rainfall to a common outlet such as the outflow of a reservoir, mouth of a bay, or any point along a stream channel.
Is the hydrologic dataset complete for the United States?
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. Efforts are ongoing to complete 10- and 12-digit unit delineations within 8-digit hydrologic units extending across the U.S. – Canada border.
How are hydrologic units related to the stream network?
Simply put, hydrologic units represent the area of the landscape that drains to a portion of the stream network. More specifically, a hydrologic unit defines the areal extent of surface water drainage to an outlet point on a dendritic stream network or to multiple outlet points where the stream network is not dendritic.
How are water boundaries different from other land boundaries?
Unlike most other land boundaries that are 2 dimensional, water boundaries also include a height dimension and a time dimension. Consequently, unique laws and techniques have developed for defining and locating water boundaries.
How are hydrologic unit boundaries determined in the WBD?
Hydrologic unit boundaries in the WBD are determined based on topographic, hydrologic, and other relevant landscape characteristics without regard for administrative, political, or jurisdictional boundaries. The WBD seamlessly represents hydrologic units at six required and two optional hierarchical levels.
How to access the USGS hydrography datasets?
National Map publishes 44 services including: Base Maps (Cached), Availability/Index Overlays (US Topo, 3DEP), Theme Overlays (NHD, Names, Elevation, Transportation), Small-scale, Natural Hazards, Web Feature Services (WFS), WCS Services and more. USGS Hydrography datasets available for download are reposted on varying schedules.
How is delineation used in the watershed segmentation process?
• Delineation is part of the process known as watershed segmentation, i.e., dividing the watershed into discrete land and channel segments to analyze watershed behavior 3of 16 DELINEATION METHODS • DEM Based (Automatic Delineation)