PERMAFROST DISTRIBUTION CONTROLS ON HYDROLOGY OF THE YUKON FLATS BASIN, ALASKA

Climate-change-driven permafrost thaw in the Yukon Flats Basin of Interior Alaska is likely causing significant changes in local hydrology via intensification of groundwater fluxes and reorganization of groundwater flow patterns. Historical observations suggest that this is affecting the hydrograph and source water chemical composition of the Yukon River and its major tributaries. Observations in Yukon Flats indicate some areas are becoming drier (i.e. small lakes disappearing), while others are becoming wetter (i.e. wetland formation). Groundwater fluxes influence soil moisture conditions and the distribution of surface water; thus, groundwater - permafrost interactions have major implications for biogeochemical cycling of carbon and nutrients, species composition and distribution of plant communities, and wildlife habitat. Because the Yukon Flats Basin encompasses a transition between continuous and discontinuous permafrost coverage, it is especially vulnerable to ecosystem change resulting from climate warming and permafrost degradation. We simulated regional groundwater flow in Yukon Flats for a variety of permafrost configurations that span a spectrum of degradation states to explore permafrost-groundwater dynamics. Model simulations are utilized to 1) illustrate linkages between groundwater flow patterns and permafrost distribution, 2) identify the most sensitive parameters that warrant augmented data collection effort, and ultimately, 3) anticipate future consequences of permafrost degradation on water and ecosystem resources.