Measuring the soil water content profile of a sandy soil with an off-ground monostatic ground penetrating radar
article
We explore the possibility of measuring a continuously variable soil moisture profile by inversion of a ground penetrating radar (GPR) signal. Synthetic experiments were conducted to demonstrate the well- posedness of the inverse problem for the specific case of identifying a soil moisture profile in hydrostatic equilibrium with a water table. In this case, the profile agrees with the water retention curve of the soil. The analysis subsequently extends to an actual case study in con- trolled outdoor conditions on a large tank filled with sand. Due to the presence of a discontinuity in the actual dielectric profile, inversion of the continuous model (Model 1) led to poor results. Only the surface soil moisture was well estimated. Including the observed dis- continuity in the model (Model 2) led to a good estimation of the water content profile. Finally, we observed that the surface water con- tent can be accurately estimated using a simplified three-layer model (Model 3). Generally, the observed confidence intervals on the esti- mated parameters are large, which denotes a lack of model sensitivity to the soil parameters. We attributed the low sensitivity to the high operating frequency range. Lower frequencies would have been re- quired to obtain more information from the larger depths. Never- theless, high frequencies allowed for an accurate estimation of the surface soil moisture, which offers particularly promising perspec- tives in humanitarian demining and agricultural applications. © Soil Science Society of America.
Topics
Frequency estimationGeological surveysGroundwaterInverse problemsMoistureRadarRadar measurementSoil moistureSoilsSurface watersGround Penetrating RadarGround penetrating radar (GPR)High operating frequencyHydrostatic equilibriumSoil moisture profilesVariable soil moisturesWater content profilesWater retention curveGround penetrating radar systems
TNO Identifier
953736
ISSN
15391663
Source
Vadose Zone Journal, 3(4), pp. 1063-1071.
Pages
1063-1071
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