Georadar for small-scale high-resolution dielectric property and water content determination of soils

To understand processes and dynamics linked to the volumetric water content of soils thorough knowledge of the water distribution inside soils is required. The applicability of the georadar technique for small scale soil heterogeneity mapping and monitoring is investigated using four different methods. Since the uppermost meter of the soil lacks a sufficient amount of spacious reflectors no standard georadar methods can supply adequate coverage of the investigated area under field conditions. Therefore four methods were evaluated to present an assortment of the most promising methods for different case specific problems. Owing to the averaging nature of the georadar technique the introduced methods needed to be adapted to small scale investigations. Based on numerical simulations and concise measurements new processing procedures are applied to achieve the required spatial resolution of less than 0.3 m. All four methods were successfully applied during realistic field measurement conditions. The transmission method is applied to a soil column experiment filled with undisturbed natural soil. In the course of an irrigation experiment the infiltration of the water front as well as the water dynamics afterwards were reproduced. The application of georadar transmission tomography provided spatial allocatable water content distributions over the time of the water seepage with spatial accuracies of approximately 0.1 m and a temporal resolution of approximately 30 min...thesi