Federal Guidelines, Requirements, and Procedures for the National Watershed Boundary Dataset: Chapter 3 of Section A, Federal Standards, Book 11, Collection and Delineation of Spatial Data

摘要

The Watershed Boundary Dataset (WBD) is a comprehensive aggregated collection of hydrologic unit data consistent with the national criteria for delineation and resolution. This document establishes interagency guidelines for creating the WBD as seamless and hierarchical hydrologic unit data, based on topographic and hydrologic features across the United States. This document provides guidelines, requirements, and procedures for expanding and revising the previous U.S. Geological Survey (USGS)-Natural Resources Conservation Service (NRCS) national data published in 1994. Expansion is accomplished by creating two additional levels of detailed hydrologic unit boundaries nested within the 1:250,000-scale hydrologic units, and revision occurs through increasing the data resolution to 1:24,000-scale in the conterminous United States, 1:25,000 scale in the Caribbean, and 1:63,360 scale in Alaska. The guideline contains details for compiling the two additional levels, Watersheds (5th-level, 10-digit hydrologic units) and Subwatersheds (6th-level, 12-digit hydrologic units), to be incorporated into the WBD. The guidelines are designed to enable local, regional, and national partners to consistently and accurately delineate watersheds. Such consistency improves watershed management through efficient sharing of information and resources and by ensuring that digital geographic data are usable with other related Geographic Information System (GIS) data.