HR: 1340h
AN: H13D-1535    [Abstracts]
TI: Assessing Streambed Recharge Under a Wide Range of Flow Conditions Using Time-series Analysis of Streambed Thermographs
AU: Hatch, C E
EM: chatch@pmc.ucsc.edu
AF: UCSC Earth & Planetary Sci. Dept., E&MS A232, 1156 High Street, Santa Cruz, CA 95064, United States
AU: Hatch, C E
EM: chatch@pmc.ucsc.edu
AF: UNR Dept. of Geological Sci. & Engr., 1664 N. Virginia St., Reno, NV 89557, United States
AU: * Fisher, A T
EM: afisher@pmc.ucsc.edu
AF: UCSC Earth & Planetary Sci. Dept., E&MS A232, 1156 High Street, Santa Cruz, CA 95064, United States
AU: * Fisher, A T
EM: afisher@pmc.ucsc.edu
AF: IGPP UCSC, E&MS A232, 1156 High Street, Santa Cruz, CA 95064, United States
AU: Constantz, J
EM: jconstan@usgs.gov
AF: USGS, 345 Middlefield Road, Menlo Park, CA 94025, United States
AU: Sigler, R
EM: rsigler@pmc.ucsc.edu
AF: UCSC Earth & Planetary Sci. Dept., E&MS A232, 1156 High Street, Santa Cruz, CA 95064, United States
AU: Stemler, G
EM: gregstemler@gmail.com
AF: UCSC Earth & Planetary Sci. Dept., E&MS A232, 1156 High Street, Santa Cruz, CA 95064, United States
AB: We evaluate downward streambed seepage in Corralitos Creek, a second-order stream in central coastal California, using differential gauging and time-series analysis of long-duration, streambed temperature records. Discharge and thermal data were collected throughout the water year at multiple locations along a 9.73-km experimental reach. Differential discharge measurements were made at various locations along the reach using the velocity-area method andusing continuous gauges installed at fixed stations. The analytical method used to interpret streambed thermal data uses changes in the phase and amplitude of subsurface diurnal temperature variations to infer the direction and rate of seepage once per day. Differential discharge data indicate that Corralitos Creek loses 0.1 to 0.2 m ³/s when channel discharge into the reach is \?1.5 m³/s, with most of the loss occurring where the stream is in direct contact with permeable aquifer units. Higher channel discharges occur mainly in the winter rainy season, during and soon after precipitation events. Differential gauging is not practical in Corralitos Creek during high flow events, but seepage rates have been calculated from thermal data in the area of greatest differential discharge throughout the water year. Streambed seepage rates calculated from thermal data are -1 to -4 m/day at times when differential discharge data can be collected, and similarly large, negative seepage rates continue during periods of high discharge, when differential discharge measurements are not practical. The area of rapid streambed seepage goes dry for periods of weeks to months late in the water year, but seepage rates of up to -1 m/day are documented soon after the streambed rewets, indicating a rapid transition from dry to actively-recharging conditions in the streambed. Geochemical data indicate that much of the documented streambed seepage along this section of Corralitos Creek recharges regional aquifers. When summed overthe entire water year, channel losses on a short reach of Corralitos Creek (watershed area ~60 km²) comprise up to 20% of the sustainable yield of the Pajaro Valley Ground Water Basin (area ~390 km²).
DE: 1829 Groundwater hydrology
DE: 1830 Groundwater/surface water interaction
DE: 1832 Groundwater transport
DE: 1872 Time series analysis (3270, 4277, 4475)
DE: 1878 Water/energy interactions (0495)
SC: Hydrology [H]
MN: 2007 Fall Meeting