| Description | Ground-penetrating radar (GPR) reflection tomography algorithms allow non-invasive monitoring of water
content changes resulting from flow in the vadose zone. The
approach requires multi-offset GPR data that are traditionally
slow to collect. We automate GPR data collection to reduce
the survey time significantly, thereby making this approach
to hydrologic monitoring feasible. The method was evaluated using numerical simulations and laboratory experiments
that suggest reflection tomography can provide water content
estimates to within 5 % vol vol−1–10 % vol vol−1
for the synthetic studies, whereas the empirical estimates were typically
within 5 %–15 % of measurements from in situ probes. Both
studies show larger observed errors in water content near the
periphery of the wetting front, beyond which additional reflectors were not present to provide data coverage. Overall,
coupling automated GPR data collection with reflection tomography provides a new method for informing models of
subsurface hydrologic processes and a new method for determining transient 2-D soil moisture distributions. | en_US |
