Using GPR to Observe the Distribution of Soil Moisture and Reflector in Alpine Meadow of Urumqi Southern Mountain

Abstract

Rapid determination of soil moisture in the arid area has important ecological significance and practical value. This study carried out a series of measurements in the alpine meadow of Urumqi Southern Mountain on April 28th, 2011 right after the snow melt. Ground-penetrating radar (GPR), time domain reflectometry (TDR) were used simultaneously for measuring the soil moisture of a 50 × 50 m2 plot, and a vertical soil profile was dug for validation analysis. The results show that: (1) a clear and continuous reflective layer in the experimental plot can be found from the GPR radar data and have a depth range from 0.362 to 0.656 m, while the GPR calculated average soil moisture above this layer is approximate 0.191 ~ 0.341; (2) TDR derived soil moistures of surface 10 cm and 20 cm depth show a consistent distribution with GPR measurements, and the former is slightly higher than the latter is likely to be due to the snow melt water accumulated more in the surface layer and not transferred immediately to the deep; (3) the vertical soil profile displays a actual compacted layer which is just at same position with the corresponding GRP measured reflective layer, and the TDR measured average soil moisture above this layer is only 0.001 less than the GPR derived data. The results give fully demonstrates to the accuracy of GPR reflected wave model to measure soil reflector and average moisture, which provides a scientific and effective technique for field-scale soil moisture and structure studies.