HR: 1340h
AN: H13D-1543    [Abstracts]
TI: Spatial and Temporal Variability of Hydraulic Properties in the Russian River Streambed, Central Sonoma County, California
AU: * Gorman, P D
EM: pgorman@pesenv.com
AF: PES Environmental, Inc., 1682 Novato Blvd; Ste 100, Novato, CA 94946, United States
AU: Constantz, J
EM: jconstan@usgs.gov
AF: U.S. Geological Survey, National Research Program Water Resources Division 345 Middlefield Rd MS496, Menlo Park, CA 94025, United States
AU: LaForce, M J
EM: laforce@clackamas.edu
AF: Clackamas Community College, Engineering Science Water and Environmental Technology Oregon City Campus 19600 S. Mollalla Avenue, Oregon City, OR 97045, United States
AB: The reach of the Russian River flowing through Sonoma County, CA, is important to fisheries and recreations, as well as being essential to the water resources infrastructure of the county. An improved understanding of the manner in which streambed sediments impact rates of ground-water recharge is essential in optimizing withdrawals without increasing potential impacts on fishery habitats and recreational needs. Temporal and spatial variations of flux and vertical hydraulic conductivity (Kv) were measured in the streambed along the Russian River at multiple locations. In-situ flux and Kv measurements were made using a modified seepage meter equipped with piezometers during monitoring events performed in June 2003, September 2003, and March 2004. Additionally, bulk sediment samples were collected during the monitoring events to characterize the grain size distribution of the streambed. Three different streambed locations (near-bank, midpoint, and thalweg) were monitored and sampled at five different sample locales in a 20-km reach of the Russian River. Vertical hydraulic conductivity of the streambed ranged from 8.55x10-5 cm/sec to 1.52x10-1 cm/sec. Significantly (p<0.05) higher values of Kv were found near the banks of the Russian River, and Kv increased (30% to an order of magnitude) after the winter storm season of 2004. Flux varied from -240 to 600 cm/day, which indicates both gaining and losing reaches of the stream occur in our study area. These findings will assist in developing a MODFLOW ground-water flow simulation that incorporates the variable streambed conductance values determined along this reach of the Russian River.
DE: 1825 Geomorphology: fluvial (1625)
DE: 1830 Groundwater/surface water interaction
DE: 1838 Infiltration
DE: 1856 River channels (0483, 0744)
DE: 1895 Instruments and techniques: monitoring
SC: Hydrology [H]
MN: 2007 Fall Meeting