Tuesday, April 30, 2013: 2:55 p.m.
Regency West 4 (Hyatt Regency San Antonio)
We present measurements of transient streaming potentials in lab-scale simula-
tions of unconfined aquifer pumping tests and explore their use for estimating
subsurface hydraulic properties. The data were collected in a series of experi-
ments conducted in a cylindrical tank filled with an 85 cm thick layer of sand
saturated to a depth of 60 cm. A constant head boundary condition was main-
tained around the sand tank circumference. It is instrumented with 3 pressure
transducers, 40 Ag/AgCl and Pb/PbCl2 electrodes and 10 TDR soil moisture
sensors. These instuments provide direct measurements of drawdown, stream-
ing potential, and soil moisture response to pumping. A 5 cm slotted PVC
tubing at the center of the sand tank serves as the pumping well. A Keithley
2701 data logger, which serves as a high impedance voltmeter, is used to read
the voltage differences between the electrodes in the sand tank and a reference
electrode placed in the constant head annulus. Streaming potential data are
used to infer hydraulic head at the measurement points and directly estimate
hydraulic properties. These are compared to parameter estimates obtained di-
rectly from drawdown and soil moisture measurements. The work demonstrates
that streaming potentials have comparable information content to the more di-
rect methods of measuring the hydraulic system state. They have the potential
to serve as a substitute for, or provide complementary datasets to, these di-
rect methods, yielding spatially dense measurements of system state that are
otherwise impracticable with direct methods.
tions of unconfined aquifer pumping tests and explore their use for estimating
subsurface hydraulic properties. The data were collected in a series of experi-
ments conducted in a cylindrical tank filled with an 85 cm thick layer of sand
saturated to a depth of 60 cm. A constant head boundary condition was main-
tained around the sand tank circumference. It is instrumented with 3 pressure
transducers, 40 Ag/AgCl and Pb/PbCl2 electrodes and 10 TDR soil moisture
sensors. These instuments provide direct measurements of drawdown, stream-
ing potential, and soil moisture response to pumping. A 5 cm slotted PVC
tubing at the center of the sand tank serves as the pumping well. A Keithley
2701 data logger, which serves as a high impedance voltmeter, is used to read
the voltage differences between the electrodes in the sand tank and a reference
electrode placed in the constant head annulus. Streaming potential data are
used to infer hydraulic head at the measurement points and directly estimate
hydraulic properties. These are compared to parameter estimates obtained di-
rectly from drawdown and soil moisture measurements. The work demonstrates
that streaming potentials have comparable information content to the more di-
rect methods of measuring the hydraulic system state. They have the potential
to serve as a substitute for, or provide complementary datasets to, these di-
rect methods, yielding spatially dense measurements of system state that are
otherwise impracticable with direct methods.
