On the reliability of current GPR ground wave methods for determining near-surface water contents

We explore the stability of the Ground-Penetrating Radar (GPR) ground wave signal and its applicability for measuring near-surface water contents along a 0.6 km long measurement line, crossing several vegetated sand dunes at a semi-desert site in Northwestern China. We find that the direct ground wave signal is a stable proxy for measuring near-surface soil moisture. However, the absolute water content may be difficult to establish without additional auxiliary information (e.g. through TDR point measurements). This is mainly due to limitations of the current feature-to-feature evaluation of the air- and ground wave wavelets.