USGS Hydrologic Units

{
  "id": "MLC-T-ENV-029414",
  "term": "USGS Hydrologic Units",
  "field": "Environment",
  "definition": "Hierarchical subdivision of land area of United States based on hydrology. \"Provide a standardized base for use by water-resource organizations in locating, storing, retrieving, and exchanging hydrologic data, in indexing and inventorying hydrologic data and information, in cataloging water-data acquisition activities, and in a variety of other applications.\" (USGS Water-Supply Paper 2294, 1987) A cataloging unit is a geographic area representing part or all of a surface drainage basin, a combination of drainage basins, or a distinct hydrologic feature. Almost all cataloging units are larger than 1800 sq km except in special circumstances. National maps available for 1, 2, 3, and 4th fields: regions (21), subregions (222), accounting units (352), cataloging units (2150). Being extended to 5th and 6th fields. Approximately 50% of units at any level correspond to \"true\" watersheds.",
  "abbreviation": "HUCs",
  "subject": "Water",
  "references": [
    "Aquatic Resource Monitoring - Terminology"
  ],
  "url": "https://mlchart.com/terminology/environment/usgs-hydrologic-units/"
}