National Hydrography Dataset
Data Specifications
- Area of Coverage: Available nationwide
- Date(s) Available: The USGS relies on a stewardship program with input from local sources to keep the data up to date
- Format: ESRI Shapefiles or Geodatabase
- Resolution: Nationwide at 1:24,000-scale (high resolution) and 1:100,000-scale (medium resolution) and at 1:63,360-scale for Alaska
- Accuracy: At 1:100,000-scale, ninety percent of well-defined features are within 167 feet (0.02 inches at map scale) of their true geographic position. The positional accuracy may vary with higher-resolution data due to processing procedures of the contributing sources. USGS map accuracy standards for 1:24,000-scale require ninety percent of well-defined features to lie within 40 feet of their true geographic position.
Overview
The National Hydrography Dataset (NHD) is a geospatial theme for surface water hydrography (hydrography is the scientific description and analysis of the physical conditions and related characteristics of the earth's surface waters). The data are obtained from topographic maps and additional sources. These data are designed to be used in general mapping and in the analysis of surface-water systems via geographic information systems (GIS). In mapping, the NHD is used with other data themes such as elevation, boundaries, and transportation to produce general reference maps.