Measuring Soil Water Content with Ground Penetrating Radar: A Decade of Progress

TLDR

Ground‑penetrating radar has advanced dramatically over the past 25 years, enabling reliable detection, mapping, and quantitative estimation of soil water content in vadose zone hydrology. This update critically reviews recent advances in vadose‑zone GPR, focusing on new acquisition and processing strategies. The review synthesizes developments in multi‑offset and borehole GPR, quantitative off‑ground methods, full‑waveform inversion, time‑lapse measurements, and instrumentation improvements. The authors conclude that GPR is a viable, powerful tool for soil‑water‑content determination and subsurface hydrological process elucidation, urging wider adoption by the hydrology community.

Abstract

Core Ideas There has been tremendous progress in GPR as a tool for soil water content determination. Numerous studies have shown the potential of GPR to detect and map SWC. We highlight new possibilities and achievements for GPR acquisition and processing strategies. Quantitative SWC detection and hydrological parameter estimation are possible using GPR. We encourages other communities to embrace GPR as a tool for SWC determination. Tremendous progress has been made with respect to ground penetrating radar (GPR) equipment, data acquisition, and processing since the establishment of GPR as a tool for soil water content determination in vadose zone hydrology about 25 yr ago. In this update, we aim to provide a critical overview of recent advances in vadose zone applications of GPR with a particular focus on new possibilities for multi‐offset and borehole GPR measurements, the development of quantitative off‐ground GPR methods, full‐waveform inversion of GPR measurements, the potential of time‐lapse GPR measurements for process investigations and hydrological parameter estimation, and recent improvements in GPR instrumentation. We hope that this update encourages the soil hydrology, groundwater, and critical zone community to embrace GPR as a viable tool for soil water content determination and the elucidation of subsurface hydrological processes.