HR: 15:25h
AN: H33G-08    [Abstracts]
TI: Groundwater Evaporation From a Playa in Spring Valley, Nevada
AU: * Thomas, J M
EM: jthomas@dri.edu
AF: Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512 United States
AU: Deverel, S
EM: sdeverel@hyrofocus.com
AF: HydroFocus, Inc., 2727 Del Rio Pl, suite B, Davis, CA 95616 United States
AU: Decker, D L
EM: dave.decker@dri.edu
AF: Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512 United States
AU: Earman, S
EM: sam.earman@dri.edu
AF: Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512 United States
AU: Mihevc, T
EM: todd.mihevc@dri.edu
AF: Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512 United States
AU: Acheampong, S
EM: stephen.acheampong@snwa.com
AF: SNWA Resources, 1900 E. Flamingo Rd, Ste. 180, Las Vegas, NV 89119 United States
AB: Bare soil playa evaporation from shallow groundwater is an important discharge component of the groundwater budget for topographically-closed basins in Nevada. However, playa groundwater evaporation is difficult to estimate. Deuterium and oxygen-18 isotopic values and chloride concentrations of soil water were used to estimate groundwater evaporation from the Yelland Playa in Spring Valley, eastern Nevada. The depth distribution of stable isotopes and chloride in soil water beneath the playa surface and the electrical conductivity of the shallow groundwater indicate prolonged evaporation of the shallow groundwater through a dry soil. Analysis of deuterium, oxygen-18 and chloride data produced similar estimated evaporation rates for two sites on the playa. At one site near the edge of the playa, the calculated evaporation rate was 11 to 14 mm/yr; at a second site near the center of the playa, the calculated evaporation rate was 39 to 43 mm/yr. These results indicate that the method is applicable for estimating bare soil evaporation rates for Nevada playas. However, the data collected for this study indicate disequilibrium, especially at the site near the center of the playa. The cause of the apparent disequilibrium is uncertain, but may be the result of declining groundwater levels due to recent drought conditions.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1818 Evapotranspiration
DE: 1829 Groundwater hydrology
DE: 1836 Hydrological cycles and budgets (1218, 1655)
SC: Hydrology [H]
MN: Fall Meeting 2005