Event Title

Water Content and Electrical Conductivity Assessment Using Small-Scale Multifunctional Heat-Pulse Sensors

Presenter Information

Robert Heinse
Kelly Lewis
Scott B. Jones

Location

Eccles Conference Center

Event Website

http://water.usu.edu/htm/conference/past-spring-runoff-conferences

Start Date

27-3-2006 5:00 PM

End Date

27-3-2006 5:15 PM

Description

Water content and electrical conductivity are key parameters for predicting transport of water and solutes in hydrological sciences. Measurements of these dynamic physical characteristics are often needed at a small-scale that is masked by field-scale surveys. For example, measurements in the first few centimeters of the soil surface (e.g., remotely sensed measurement calibration) or within a root system (e.g., where plant uptake is critical) necessitate small-scale sensors that provide soil water content and electrical conductivity estimates within a comparable sampling volume. Under saline conditions, common in the Great Salt Lake Basin, measurements with state-of-the-art electromagnetic methods fail because of signal attenuation associated with the high electrical conductivity of the soil. Under these conditions sensors that predict water content using principles of heat dissipation are insensitive to salinity. Our objectives were to design, construct and test a novel sensor providing estimates of water content and electrical conductivity. The heat-pulse sensor is constructed of dual parallel needles, one of which serves as a heater while the other contains a thermistor for temperature measurement. We evaluated direct current electrical conductivity measurements in a four-electrode configuration formed by integrating two dual-probe heat-pulse sensors. The experiments monitored water content and electrical conductivity in samples of baked clay media. We will show data from the heat-pulse and electrical conductivity measurements using convective and diffusive solute transport experiments. Specifically, we advocate the use of the multifunctional sensors for non-invasive tomographical studies. Combining the heat-pulse water content determination with electrical conductivity measurements will provide improved environmental assessment capabilities.

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Mar 27th, 5:00 PM Mar 27th, 5:15 PM

Water Content and Electrical Conductivity Assessment Using Small-Scale Multifunctional Heat-Pulse Sensors

Eccles Conference Center

Water content and electrical conductivity are key parameters for predicting transport of water and solutes in hydrological sciences. Measurements of these dynamic physical characteristics are often needed at a small-scale that is masked by field-scale surveys. For example, measurements in the first few centimeters of the soil surface (e.g., remotely sensed measurement calibration) or within a root system (e.g., where plant uptake is critical) necessitate small-scale sensors that provide soil water content and electrical conductivity estimates within a comparable sampling volume. Under saline conditions, common in the Great Salt Lake Basin, measurements with state-of-the-art electromagnetic methods fail because of signal attenuation associated with the high electrical conductivity of the soil. Under these conditions sensors that predict water content using principles of heat dissipation are insensitive to salinity. Our objectives were to design, construct and test a novel sensor providing estimates of water content and electrical conductivity. The heat-pulse sensor is constructed of dual parallel needles, one of which serves as a heater while the other contains a thermistor for temperature measurement. We evaluated direct current electrical conductivity measurements in a four-electrode configuration formed by integrating two dual-probe heat-pulse sensors. The experiments monitored water content and electrical conductivity in samples of baked clay media. We will show data from the heat-pulse and electrical conductivity measurements using convective and diffusive solute transport experiments. Specifically, we advocate the use of the multifunctional sensors for non-invasive tomographical studies. Combining the heat-pulse water content determination with electrical conductivity measurements will provide improved environmental assessment capabilities.

http://digitalcommons.usu.edu/runoff/2006/AllAbstracts/42