At the core of our Nonpoint Source Assessment Tool (NPSAT) is software for the simulation of a high-resolution steady-state flow solution in an unconfined and variably confined aquifer system. We have developed our own, highly efficient numerical algorithm to accurately solve the groundwater flow equation for such conditions. The algorithm is based on an adaptive mesh refinement approach that is both, highly efficient and very detailed where needed. This peer-reviewed paper in one of the most highly respected international water science journals describes our methodology, a thorough validation of the algorithm, and several example applications that demonstrate the utility of this software. The software is in the public domain and links to the software are provided in the paper.
The following figures show examples of the iterative mesh refinement implemented by the algorithm: