Modeling transient streaming potentials in coupled saturated-unsaturated zone flow to a pumping well
Abstract
A semi-analytical model for transient response of streaming potentials (SP) to pumping in an unconfined aquifer, taking into account unsaturated zone flow, is presented. Flow in the unsaturated zone is modeled with a linearized Richards' equation with the moisture retention curve and unsaturated hydraulic conduc- tivity assumed to be exponential functions of matric potential. For the case presented here, the same sorption number is assumed for moisture retention and unsaturated hydraulic conductivity. The ratio of the unsaturated to satu- rated electrokinetic coupling coefficient is described by Cℓ,r = kr Sw-(d+1), where kr is relative hydraulic conductivity, Sw is saturation, and d is Archie's second exponent. Hence, based on the assumption of an exponential moisture retention curve, Cℓ,r is also an exponential function of matric potential. Model predicted responses in the saturated and unsaturated zones are compared with measured SP responses to pumping in a bench-scale experimental setup that simulates a radially bounded unconfined aquifer. Potential for using SP responses to esti- mate saturated and unsaturated hydraulic parameters is evaluated. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04- 94AL85000. This research is funded by WIPP programs administered by the Office of Environmental Management (EM) of the U.S Department of Energy.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.H43D1369M
- Keywords:
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- 1829 HYDROLOGY / Groundwater hydrology;
- 1835 HYDROLOGY / Hydrogeophysics