HUC

Huc commonly refers to the Hydrologic Unit Code (HUC), a standardized coding system used by the United States Geological Survey to identify watersheds and drainage basins in the United States and its territories. The system is hierarchical, with shorter codes representing broader geographic regions and longer codes denoting finer subdivisions of drainage areas.

HUCs are issued at multiple levels, typically including two-digit regional codes, four-digit subregions, six-digit basins, and eight-digit subbasins, with ten- or twelve-digit codes used for even finer delineations in some datasets. Each level corresponds to a defined hydrologic unit, allowing agencies and researchers to organize and compare hydrologic data consistently. The codes facilitate aggregation and interoperability across datasets such as streamflow measurements, water quality data, land use information, and ecological assessments.

In practice, HUCs support a range of activities, including water-resource planning, environmental monitoring, watershed management, and geographic information system (GIS) analysis. They enable analysts to link hydrologic information to specific drainage areas, compare conditions across regions, and track changes over time within defined hydrologic units.

Although the Hydrologic Unit Code is most closely associated with U.S. hydrology, the general concept of hierarchical geographic coding for watersheds appears in other countries under different naming schemes. Within hydrologic and geospatial information systems, however, the HUC remains a widely used standard for organizing watershed-related data.