Hydrologic Classification of Bristol Bay, Alaska Using Hydrologic Landscapes

The use of hydrologic landscapes has proven to be a useful tool for broad scale assessment and classification of landscapes across the United States. These classification systems help organize larger geographical areas into areas of similar hydrologic characteristics based on climate, terrain and underlying geology. Such characterization of landscapes into areas of common hydrologic patterning is particularly instructive where site specific hydrologic data is sparse or spatially incomplete. By using broad scale landscape metrics to organize the landscape into discrete, characterized units, natural resources managers can gain valuable understanding of landscape patterning and how locations may be differentially affected by a variety of environmental stressors ranging from land use change to climate change.

The heterogeneity of aquatic habitats and undisturbed hydrologic regimes within Bristol Bay are a known principal driver for its overall fisheries stability and the use of hydrologic landscapes offers the ability to better characterize the hydrologic and landscape influences on structuring biotic populations at a regional scale. Here we classify the entire Bristol Bay region into discrete hydrologic landscape units based on indices of annual climate and seasonality, terrain, and geology. We then compared hydrologic landscape units to locations of available long term streamflow for characterization of expected hydrologic behavior where streamflow data was lacking. This demonstration of hydrologic landscapes in Bristol Bay, Alaska shows the utility of using large-scale datasets on climate, terrain and geology to infer broad scale hydrologic patterning within a data poor area. Disclaimer: The authors' views expressed here do not necessarily reflect views or policies of USEPA.