Seasonally frozen soil plays play an important role in the hydrology in 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. The Simultaneous Heat and Water (SHAW) model was applied to data collected at the Lower Sheep Creek site to simulate the impacts of sparse vegetation on heat and water transfer associated with frozen soil infiltration and runoff. The SHAW model is a detailed process model which simulates heat, water and solute movement through a plant-snow-residue-soil system. The system is represented by integrating detailed physics of vegetation cover, snow, residue and soil into one simultaneous solution. Interrelated heat, water and solute fluxes are computed throughout the system and include detailed provisions of soil freezing and thawing.
Data were collected at the Lower Sheep Creek Watershed within the Reynolds Creek Experimental Watershed to study processes associated with infiltration and runoff associated with frozen soil infiltration and runoff. Lower Sheep Creek has sparse sagebrush vegetation. Miniature (approximately 1 m2) runoff plots were established to measure runoff from individual sagebrush plants and the essentially bare ground in the interspace areas between sagebrush plants. Comparison of simulated unfrozen water content with fiberglass moisture blocks and TDR measurements showed good response for simulating moisture migration to the freezing front. Simulation results also compared well with measurements of soil temperature and runoff for areas both with and without vegetation cover.
Gerald N. Flerchinger USDA Agricultural Research Service 800 Park Blvd, Suite 105 Boise, ID 83712 Phone: 208-334-1363 Fax: 208-334-1502 E-mail: gflerchi@nwrc.ars.pn.usbr.govMark S. Seyfried USDA Agricultural Research Service 800 Park Blvd, Suite 105 Boise, ID 83712 Phone: 208-336-5696 Fax: 208-336-1502 E-mail: mseyfrie@nwrc.ars.pn.usbr.gov