Evolving patterns of coupled glacio-hydrology across the Pacific Northwest Region, USA

Wednesday, 17 December 2014: 3:10 PM
Chris D Frans1, Erkan Istanbulluoglu1, Dennis P Lettenmaier2, Andrew G Fountain3, Matthew Bachmann4 and Garry K C Clarke5, (1)Univ of Washington, Seattle, WA, United States, (2)University of California Los Angeles, Los Angeles, CA, United States, (3)Portland State University, Portland, OR, United States, (4)US Geological Survey, Tacoma, WA, United States, (5)University of British Columbia, Vancouver, BC, Canada
Recession of mountain glaciers in partially glacierized headwater catchments has the potential to impact watershed dynamics in a range of ways, including reduced low flows, erosion of exposed steep soils, increased sediment transport, and ecosystem succession. The response of glaciers and glacierized watershed processes to progressive climatic warming will vary greatly with local environmental attributes (aspect, hypsometry, slope, debris cover) and climatic forcing (topography driven climatic gradients, prevailing wind direction, precipitation variability and perturbation). To identify the relative influence of these controlling factors and to identify locations where these changes will have significant influence on stream discharge in the U.S. Pacific Northwest (PNW), we gather a rich data set of glacio-hydrological variables and use a recently developed glacio-hydrology model in conjunction with data to evaluate the hydrologic response of partially glacierized river basins at a range of spatial and temporal scales. The distributed hydrologic modeling framework, which incorporates a physical representation of changes in glacier area through glacier dynamics, allows the analysis of hydrologic and glaciological change at extended temporal and fine spatial scales. Among the river basins we examine are the Hoh River on the Olympic Peninsula of Western Washington, the Hood River in Northern Oregon, the Nisqually River in the Puget Sound drainage basin, and multiple watersheds in the North Cascades Region. For each of these basins, tipping points of hydrologic response to glacier recession are identified and projected. We 1) describe varied patterns of coupled glacio-hydrologic response 2) identify influential environmental controls and 3) identify vulnerable areas in space and time. We close with a discussion of the implications of ongoing and projected glacio-hydrologic changes for the management of water and natural resources in the PNW.