HR: 1340h
AN: H13D-1547    [Abstracts]
TI: Determining Water Fluxes Across Surface Water/Groundwater Interfaces Using Temperature Data and Numerical Models
AU: * Fleming, B J
EM: bfleming@geo.umass.edu
AF: Geoscience Department, University of Massachusetts, Amherst, 233 Morrill Science Center, 611 North Pleasant Street, Amherst, MA 01003,
AU: Boutt, D F
EM: dboutt@geo.umass.edu
AF: Geoscience Department, University of Massachusetts, Amherst, 233 Morrill Science Center, 611 North Pleasant Street, Amherst, MA 01003,
AB: Daily water releases from an upstream dam on the Deerfield River create significant differences in stage of up to .5 meters. These differences cause the river to change from a gaining stream to a losing stream on a daily basis. In this study, we use Thermochron iButtons to measure changes in groundwater temperature to assess water fluxes between the river and surficial aquifer. The causes for the temperature changes observed in the groundwater are (1) diurnal heating of surface water as air temperatures increase, and (2) changes in temperature caused by an influx of reservoir water from dam releases. We deploy a pressure transducer with iButtons which are inserted into the riverbed and riverbank at 10 cm intervals to create thermal cross sections. To account for heterogeneity in the riverbed material, the iButtons are installed along three cross section lines. One line is in coarse sand and gravel, another is in sand and silt, and the third, which is the control, is on an unregulated river that flows into the Deerfield. The control, which is downstream of the first two sites, only experiences temperature variations caused by diurnal air temperature changes. The temperature data are used to calibrate coupled numerical models of groundwater flow and heat transport. Through these models we can derive hydraulic conductivity estimates of the riverbed material, groundwater velocities during release events, and water fluxes across the surface water-groundwater interface. Groundwater velocity and flux estimates are useful for evaluating mass transport mechanisms and nutrient cycling in the near stream environment.
DE: 1808 Dams
DE: 1830 Groundwater/surface water interaction
DE: 1847 Modeling
DE: 1860 Streamflow
DE: 1878 Water/energy interactions (0495)
SC: Hydrology [H]
MN: 2007 Fall Meeting