HR: 14:55h
AN: H23G-06    [Abstracts]
TI: Spatial variability of induced ground-water recharge beneath the Russian River, California
AU: * Rosenberry, D O
EM: rosenber@usgs.gov
AF: U.S. Geological Survey, MS413, Bldg. 53, DFC, Lakewood, CO 80225 United States
AU: Hatch, C E
EM: chatch@es.ucsc.edu
AF: U.C. Santa Cruz, Dep't. of Earth Science, 1156 High St., Santa Cruz, CA 95064 United States
AU: Cox, M H
EM: mhcox@usgs.gov
AF: U.S. Geological Survey, MS439, 345 Middlefield Road, Menlo Park, CA 94025 United States
AU: Zamora, C
EM: czamora@usgs.gov
AF: U.S. Geological Survey, Placer Hall, 6000 J St., Sacramento, CA 95819 United States
AU: Cloud, A
EM: cloud@colorado.edu
AF: Univ. of Colorado, 619-B North St., Boulder, CO 80304 United States
AU: Constantz, J E
EM: jconstan@usgs.gov
AF: U.S. Geological Survey, MS439, 345 Middlefield Road, Menlo Park, CA 94025 United States
AU: Seymour, D
EM: dseymour@scwa.ca.gov
AF: Sonoma County Water Agency, P.O. Box 11628, Santa Rosa, CA 95406 United States
AB: The Sonoma County Water Agency extracts water from the alluvial aquifer adjacent to and beneath the Russian River via large-volume Ranney-type collector wells. To aid in this extraction, the stage of the river is increased approximately 3 meters by an inflatable dam. In addition, raising the dam allows water to be diverted into infiltration basins that are located adjacent to the river. Removal of aquifer water induces large fluxes from surface water to ground water through the beds of the infiltration basins and the river. Total extraction during maximum summer withdrawals via five collector wells indicates an average flux from surface water to ground water through the riverbed and infiltration basins of 153 cm/d. Measurements of flux using in-river and in-pond piezometers, diurnal sediment-temperature data, and seepage meters, indicate that actual seepage fluxes are spatially variable and large seepage fluxes are concentrated in specific locations, some of which may not be intuitive. For example, we expected greatest induced seepage fluxes to occur above laterals that extend beneath the river and deliver water to a collector well. Seepage flux along a transverse transect of the riverbed that was located above laterals from one of the collector wells averaged 10 cm/d. At the same time, seepage flux along a transect that was 500 m upstream, and farther from the influence of the collector-well system, averaged 40 cm/d. Seepage fluxes from the central portion of one of the recharge basins averaged 3 cm/d whereas seepage fluxes near the margin of that infiltration basin averaged 250 cm/d. Seepage fluxes derived from in-stream-piezometer Darcy calculations were surprisingly consistent with seepage fluxes derived from seepage-meter measurements. Seepage fluxes derived from temperature measurements were slightly less comparable to the piezometer and seepage-meter measurements. The 121 cm/d average of all seepage-flux measurements was similar to the spatially-integrated rate (153 cm/d) based on the volume of water extracted from the river by the pumping wells divided by the affected area of the riverbed and the flooded infiltration ponds.
DE: 1803 Anthropogenic effects
DE: 1829 Groundwater hydrology
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting