GPR study of pore water content and salinity in sand

High-resolution studies of hydrological problems of the near-surface zone can be better accomplished by applying ground-probing radar (GPR) and geoelectrical techniques. The authors report on GPR measurements (500 and 900 MHz antennae) which were carried out on a sorted, clean sand, both in the laboratory and at outdoor experimental sites. The outdoor sites include a full-scale model measuring 5 x 3 x 2.4 m{sup 3} with three buried sand bodies saturated with water of various salinities. Studies investigate the capability of GPR to determine the pore water content and to estimate the salinity. These parameters are important for quantifying and evaluating the water quality of vadose zones and aquifers. The radar technique is increasingly applied in quantifying soil moisture but is still rarely used in studying the problems of water salinity and quality. The reflection coefficient at interfaces is obtained from the amplitude spectrum in the frequency and time domains and is confirmed by 1D wavelet modelling. In addition, the GPR velocity to a target at a known depth is determined using techniques of two-way traveltime, CMP semblance analysis and fitting an asymptotic diffraction curve. The results demonstrate that the reflection coefficient increases with increasing salinity of the moisture. Thesemore » results may open up a new approach for applications in environmental problems and groundwater prospecting, e.g., mapping and monitoring of contamination and evaluation of aquifer salinity, especially in coastal areas with a time-varying fresh-water lens.« less

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