HR: 0800h
AN: U41C-0628    [Abstracts]
TI: Surface Water Storage Change as Evidence of Groundwater Gradients
AU: * Bryan, R
EM: rbryan@iarc.uaf.edu
AF: University of Alaska-Fairbanks International Arctic Research Center, PO Box 757340, Fairbanks, AK 99775-7340, United States
AU: Hinzman, L D
EM: lhinzman@iarc.uaf.edu
AF: University of Alaska-Fairbanks International Arctic Research Center, PO Box 757340, Fairbanks, AK 99775-7340, United States
AU: HInzman, K
EM: ffky@uaf.edu
AF: University of Alaska- Fairbanks Water and Environmental Research Center, Po Box 755910, Fairbanks, AK 99775-5910, United States
AB: Much of the Alaskan Arctic and Subarctic receives a minimal amount of annual precipitation. Changes to regional precipitation patterns and the general transient warming expected in the next century's lake hydrology and the associated wetlands place the risk of lakes perforating the permafrost boundary on the forefront. Lake change on the Alaskan landscape due to permafrost degradation is going to be important to local ecosystems and in, for example, providing habitat for migratory waterfowl in the next decades and centuries. Permafrost presence, absence, and thickness are interconnected in the deciphering of groundwater gradients and projection of surface water presence, absence, disappearance, and appearance on the Alaskan landscape. Detailed efforts have been made to produce datasets of presence or absence of the permafrost on the Seward Peninsula and further efforts are in place to do the same for the entire state. Continuous permafrost can provide an impervious barrier to groundwater movement and most groundwater-surface water interaction occurs in areas of discontinuous permafrost. With permafrost thawing and open talik formation in discontinuous permafrost regions, surface water formerly perched above the permafrost can drain into the subpermafrost groundwater. In contrast, in areas where the local hydraulic gradient is upwards, subpermafrost groundwater may discharge at the surface as the confining layer of permafrost degrades and an open talik forms. Lake change, in the absence of changes in evaporation and surface flow, are governed by the local vertical flux of water. In this study we compile observations of surface water storage change in Alaska and conjecture that shrinking/ disappearing lakes are evidence of supra-permafrost groundwater downwelling. The resulting dataset serves as verification for our model of groundwater dynamics. The planned method for determining the ground water gradient and degree to which vertical percolation will be restricted is to analyze digital terrain information with hydrology, permafrost, soils, geology, and current climate data. To start the groundwater gradient computations we will focus on areas with known hydrologic phenomena and elaborate on a vector based gradient map referencing the steepness of the terrain and the precipitation on the surrounding higher elevations. Once the present groundwater and surface water situation is captured, based on the future subsidence of the permafrost in areas on the landscape, we propose to forecast the wetness and dryness across Alaska, capturing the uniqueness of each watershed's turn toward wetter and then drier over the next decades and centuries.
DE: 1600 GLOBAL CHANGE
DE: 1829 Groundwater hydrology
DE: 1830 Groundwater/surface water interaction
DE: 1847 Modeling
SC: Union [U]
MN: 2007 Fall Meeting