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Submitted to: International Symposium on Physics Chemistry and Ecology of Seasonally Froz
Publication Type: Proceedings Publication Acceptance Date: 12/19/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Seasonally frozen soil plays a significant role in the hydrology of northern latitudes. In many areas, rain or snowmelt on seasonally frozen soil is the single leading cause of severe runoff events, but efforts to predict frozen soil runoff have had limited success. Ice blocks the soil pores and greatly diminishes the ability of water to infiltrate the soil when the soil is frozen. The Simultaneous Heat and Water model, is capable of simulating the complex wintertime phenomena of snow accumulation and melt, detailed soil freezing and thawing including freezing-induced moisture migration, and associated frozen soil runoff. The Simultaneous Heat and Water (SHAW) model was applied to two years of data for sagebrush-covered and essentially bare ground at the Lower Sheep Creek Watershed located within the Reynolds Creek Experimental Watershed to test the ability of the model to simulate water content, and runoff from frozen soil. Freezing/thawing processes, including ice and water content, were simulated reasonably well. Total simulated runoff from both the sagebrush plots and bare interspace plots as well as timing of runoff from the interspace plots were simulated quite well. Based on results from this study, the SHAW model can be used as a tool in conjunction with other hydrologic model to assess the potential for severe flooding from seasonally frozen soils. Technical Abstract: The occurrence of frozen soil can result in significant runoff and erosion events from otherwise mild rainfall or snowmelt events. However, most hydrologic models, including most snowmelt runoff models, include no provisions for soil freezing and thawing, and thus cannot address these extreme, yet common, hydrologic events. The Simultaneous Heat and Water (SHAW) model represents one of the more detailed models of snowmelt and soil freezing and thawing, however the ability of the model to simulate frozen soil runoff has not been evaluated. Thus, the SHAW model was applied to two years of data collected on small (1 m2) runoff plots on the Reynolds Creek Experimental Watershed in southwest Idaho to demonstrate the ability of the model to simulate freezing-induced moisture migration and to test the ability of the model to simulate frozen soil runoff. Freezing/thawing processes, including liquid water content, were simulated reasonably well. Total runoff simulated from vegetation-covered plots was within the range of measured runoff, but timing was off. Both magnitude and timing of runoff from the bare plots were simulated quite well. |
