HR: 0800h
AN: H51C-0641    [Abstracts]
TI: Modeling Vegetative Controls on the Water Balance in Shallow Desert Soils
AU: * Garcia, C
EM: cgarcia@usgs.gov
AF: U.S. Geological Survey, 2730 N. Deer Run Road, Carson City, NV 89428, United States
AU: Andraski, B J
EM: andraski@usgs.gov
AF: U.S. Geological Survey, 2730 N. Deer Run Road, Carson City, NV 89428, United States
AU: Cooper, C A
EM: Clay.Cooper@dri.edu
AF: Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512, United States
AU: Wheatcraft, S W
EM: wheatcraft@unr.edu
AF: University of Nevada, Reno, Department of Geological Sciences and Engineering/172 University of Nevada, Reno, Reno, NV 89509, United States
AU: Stonestrom, D A
EM: dastones@usgs.gov
AF: U.S. Geological Survey, Bldg. 15, McKelvey Building 345 Middlefield Road, MS-421, Menlo Park, CA 94025, United States
AU: Johnson, M J
EM: johnsonm@usgs.gov
AF: U.S. Geological Survey, 2730 N. Deer Run Road, Carson City, NV 89428, United States
AB: Vegetative controls on the water balance in shallow desert soils near the Amargosa Desert Research Site, Nevada were investigated with transient, one-dimensional models. Movement of liquid water, water vapor, and heat were simulated in sparsely vegetated and non-vegetated soils. Dominant transport mechanisms simulated within the root zone (upper 100 cm) were liquid water flow subsequent to precipitation and thermal-water-vapor flow during dry periods. Liquid water fluxes were greater beneath non-vegetated soils. Thermal-water-vapor fluxes beneath vegetated soils were as much as 10 times greater than non-vegetated soils and up to 1000 times greater than liquid water fluxes during warm dry periods. Total head gradients beneath non-vegetated soils were predominantly downward while those below vegetated soils were seasonally trending with upward gradients during warm dry periods and downward gradients during cool wet periods. Moisture content beneath non- vegetated soils greatly exceeded residual moisture content observed and simulated beneath vegetated soils. Sustained root-zone moisture accumulation, which does not exist beneath vegetated soils, increases the potential for downward migration of water and contaminants.
DE: 1813 Eco-hydrology
DE: 1866 Soil moisture
DE: 1875 Vadose zone
DE: 1876 Water budgets
SC: Hydrology [H]
MN: 2007 Fall Meeting