HR: 1340h
AN: H13C-0423    [Abstracts]
TI: Use of a Spatially-Distributed, Process-Based Hydrologic Model to Simulate the Influence of Discontinuous Permafrost on Hydrologic Processes
AU: * Bolton, W R
EM: ftwrb@uaf.edu
AF: Water and Environmental Research Center, University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AU: Hinzman, L D
EM: ffldh@uaf.edu
AF: Water and Environmental Research Center, University of Alaska Fairbanks, Fairbanks, AK 99775 United States
AB: In the sub-arctic environment, permafrost is a strong factor in controlling many hydrologic processes including stream flow and soil moisture. Soil moisture, which displays a high spatial and temporal variability, is an important variable in understanding and predicting a large number of processes including land-atmosphere interactions and permafrost aggradation/degradation. In order to understand and predict ecosystem response to a changing climate and resulting feedbacks, it is critical to quantify the interaction of soil moisture and meteorology as a function of climatic processes, landscape type, and vegetation. The primary goal of our research is to describe, simulate, and predict soil moisture dynamics and all other hydrologic processes everywhere throughout a sub-arctic watershed. The model we are developing, TopoFlow, is being used as a tool to better understand the effects of vegetation and soil type, presence or absence of permafrost, the amount and timing of precipitation, and disturbance (such as wildfire) on soil moisture dynamics. Three small sub-basins of the Caribou-Poker Creeks Research Watershed (CPCRW), located 48 km north of Fairbanks, Alaska (65\deg 10'N, 147\deg 30'W), are the areas selected for study. These small sub-basins, which are underlain with approximately 3, 19, and 53% permafrost, are simulated to explore differences in permafrost versus non-permafrost areas. Discontinuous permafrost is represented though differences in hydraulic conductivity between the permafrost and non-permafrost soils. Non-permafrost soils, or soils within the seasonally thawed soils, are represented with much larger hydraulic conductivities than in permafrost soils. The primary control on local hydrological processes is dictated by the presence or absence of permafrost, but is also influenced by the thickness of the active layer and the total thickness of the underlying permafrost. As permafrost becomes thinner or decreases in areal extent, the interaction of surface and sub-permafrost ground water processes becomes more important. The inability of soil moisture to infiltrate to deeper groundwater zones due to ice rich permafrost maintains very wet soils in arctic regions. However, in the slightly warmer regions of the sub-arctic, the permafrost is thinner or discontinuous. In permafrost-free areas, surface soils can be quite dry as infiltration is not restricted, impacting ecosystem dynamics, fire frequency and latent and sensible heat fluxes.
DE: 1823 Frozen ground
DE: 1860 Runoff and streamflow
DE: 1866 Soil moisture
DE: 1878 Water/energy interactions
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting