HR: 1340h
AN: H23A-1017    [Abstracts]
TI: Comparison of Soil Moisture Content Estimated with Air-Launched and Ground-Coupled GPR Techniques
AU: * Kelly, B B
EM: kellybb@uwec.edu
AF: University of Wisconsin-Eau Claire, Department of Geology University of Wisconsin-Eau Claire, Eau Claire, WI 54702, United States
AU: Grote, K R
EM: grotekr@uwec.edu
AF: University of Wisconsin-Eau Claire, Department of Geology University of Wisconsin-Eau Claire, Eau Claire, WI 54702, United States
AB: Air-launched Ground Penetrating Radar (GPR) data are commonly used in assessment of pavement conditions for highway and bridge maintenance. These data can be collected over large distances very quickly and have relatively simple data processing requirements, so data processing is usually automated. In contrast, ground- coupled GPR data must be collected more slowly, and ground-coupled data used for soil moisture content estimation usually require a user who is experienced in GPR data interpretation. Thus, air-launched GPR data are used relatively easily for commercial applications, while ground-coupled GPR data used for soil moisture estimation have thus far primarily been employed in research applications. This experiment compares GPR data collected over wet and dry soil in the air-launched and ground-coupled modes to determine whether air-launched data could be used for accurate, field-scale soil moisture estimation. In this experiment, GPR data are collected using 250-, 500-, and 1000-MHz antennas in a large tank with controlled soil moisture conditions. The dielectric constant is determined using reflection coefficient theory for the common-offset air-launched data and electromagnetic velocity analysis of the variable-offset ground-coupled data. Data were initially collected using both the ground-coupled and air-launched modes over wet sand. Then, a 3-cm layer of dry sand was placed over the wet sand, and air-launched and ground-coupled GPR surveys were repeated. Repeated layers of sand, each 3-cm thick, were added until both air-launched and ground-coupled data show no change in dielectric constant with the addition of more dry sand. Analysis of these GPR data will allow comparisons of dielectric constants estimated from both ground-coupled and air-launched data for different frequencies and will indicate the suitability of air-launched GPR techniques for soil moisture estimation. These data will also provide experimental results for the depth of penetration of air-launched GPR signals for different frequencies.
DE: 0634 Measurement and standards
DE: 1835 Hydrogeophysics
DE: 1855 Remote sensing (1640)
DE: 1866 Soil moisture
DE: 1895 Instruments and techniques: monitoring
SC: Hydrology [H]
MN: 2007 Fall Meeting