A Practical Grid-Based Alternative Method to Advective Particle Tracking.

Advective particle tracking is a conventional groundwater modeling technique that is widely used as a screening tool but lacks robustness as a reliable method for general applications. In this work, we investigate the suitability of industry-standard, finite-difference, grid-based methods as an alternative to the conventional particle-tracking approach. The presented method is classified as a particular case of the more general forward- or backward-in-time advective-dispersive probabilistic transport approaches. The proposed method is used as a powerful screening tool to accurately delineate and visualize capture zones around abstraction wells or outflow boundaries, the swept zones formed by injection wells or inflow boundaries, and the partitions associated with injection-pumping well doublets or inflowing-outflowing boundary pairs. Moreover, we show that the forward or backward travel times and residence time distributions are robustly simulated and visualized on the computational grid with little computational effort. Two examples are given to illustrate the key advantages of this method in groundwater applications. The first example considers a synthetic pump-and-treat remediation system in an irregularly layered aquifer. The second example involves four doublet wells operating for heat extraction in the Dogger geothermal reservoir in the Paris Basin, a leading European scale project. The presented approach is far more comprehensive as a screening tool than the conventional method, providing a natural intermediate step before processing the more general time-dependent advective-dispersive simulations.