Automated water content reconstruction of zero-offset borehole ground penetrating radar data using simulated annealing

The automated inversion of water content profiles from first arrival travel time data collected with zero-offset borehole ground penetrating radar is discussed. The inversion algorithm sets out to find the water content profile that minimizes a least-squares objective function representing the difference between the modeled and measured first arrival travel time. Ray-tracing analysis is used to determine the travel time for direct and critically refracted paths to identify the first arrival travel time. This automated method offers improvement over a previously presented graphical solution that considers both direct and critical refractions. Specifically, this approach can identify thinner layers and allow for the incorporation of uncertainty in the travel time measurements to determine the depth-specific uncertainty of the inferred water content profile through multiple simulations using a stochastic approach.