Background Hydrologic Units Classification Codification
Tuesday, April 26, 2022 10:06 AMThis manual uses the following classification and codification for hydrologic units, which combines nomenclature from AISLUS, 1990 and NRSA, 1995 according to this paper.
| Hydrologic Unit | Area (ha) | Area (km2) |
|---|---|---|
| Region | 27,300,000 - 113,000,000 | 2,730,000 - 1,130,000 |
| Basin | 1,300,000 - 31,300,000 | 130,000 - 313,000 |
| Catchment | 470,000 - 6,900,000 | 47,000 - 69,000 |
| Subcatchment | 150,000 - 1,600,000 | 15,000 - 16,000 |
| Watershed | 20,000 - 350,000 | 2,000 - 3,500 |
| Subwatershed | 3,000 - 5,000 | 300 - 50 |
| Miniwatershed | 1,000 - 3,000 | 100 - 30 |
| Microwatershed | 500 - 1,000 | 50 - 10 |