You are here:
How Misapplication of the Hydrologic Unit Framework Diminishes the Meaning of Watersheds
Citation:
Omernik, J., G. Griffith, R. Hughes, J. Glover, AND M. Weber. How Misapplication of the Hydrologic Unit Framework Diminishes the Meaning of Watersheds. ENVIRONMENTAL MANAGEMENT. Springer-Verlag, New York, NY, 60(1):1-11, (2017).
Impact/Purpose:
Watersheds are a fundamental geographic unit used to study the effects of natural and anthropogenic characteristics on the quality and quantity of water. Most scientists and resource managers historically have been in agreement on the spatial meaning of the term ‘watershed’ – that is, the topographic area within which water drains to a specific point on a stream, river, or particular waterbody. The Hydrologic Unit Code (HUC) framework, however, has changed this understanding. Hydrologic units provide a convenient nationwide set of geographic polygons based on an arbitrary subdivision of the drainage of land surface at several hierarchical levels. As this paper demonstrates, treatment of watersheds and Hydrologic units as synonymous has led to misuse of terms and misunderstanding. We explain how this misuse of terms has affected the meaning of watersheds and can impair understanding of the associations of spatial geographic phenomena relative to streams. We discuss strengths and limitations of watersheds and hydrologic units as spatial frameworks, as well as provide suggested approaches for remedying misuse and misunderstanding in terminology.
Description:
Hydrologic units provide a convenient nationwide set of geographic polygons based on an arbitrary subdivision of the drainage of land surface areas at several hierarchical levels. Half or more of these units, however, are not true watersheds as the official name of the framework, Watershed Boundary Dataset (WBD), implies. Hydrologic units and watersheds are commonly treated as synonymous, and this misuse and misunderstanding can have some serious consequences. We discuss some of the strengths and limitations of watersheds and hydrologic units as spatial frameworks. Using examples from the Northwest and Southeast U.S., we explain how the misuse of the hydrologic unit framework has affected the meaning of watersheds and can impair the understanding of the associations of spatial geographic phenomena relative to a potentially infinite number of points on streams due to their linear nature.
