HR: 1340h
AN: H23A-1105    [Abstracts]
TI: Using Borehole Ground Penetrating Radar to Monitor Transient Flow during Pumping of an Unconfined Aquifer
AU: * von Glinski, G
EM: ty@hwr.arizona.edu
AF: University of Arizona, 1133 E. North Campus Drive, Tucson, AZ 85721-0011
AU: Ferre, P
EM: ty@hwr.arizona.edu
AF: University of Arizona, 1133 E. North Campus Drive, Tucson, AZ 85721-0011
AB: The contribution of the unsaturated zone to the response of an unconfined aquifer to pumping remains an area of active debate and research in hydrology. It is generally accepted that water is released from storage above the water table relatively slowly and that this delayed drainage contributes to the unique shape of pumping test responses. However, the magnitude of this contribution is in question. Furthermore, it is not clear whether moisture release curves determined under static conditions can be used to characterize the vadose zone response. In this investigation, we use borehole ground penetrating radar (BGPR) to monitor the volumetric water content throughout the vadose zone and into the shallow saturated zone during pumping in an unconfined aquifer. We show that BGPR is uniquely capable of providing water content profiles with sufficient depth and temporal resolution to characterize the vadose zone response under these transient conditions. The measurements quantify both the rate and timing of delayed drainage. In addition, the results indicate that the moisture retention characteristics, measured in the subsurface before pumping, do not adequately describe the transient response of the vadose zone. The results of this study are a promising demonstration of the current and future utility of geophysical methods to help address long standing questions in the field of hydrology.
DE: 1866 Soil moisture
DE: 1875 Unsaturated zone
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting