Teaching Numerical Groundwater Flow Modeling with Spreadsheets: Unconfined Aquifers and Multilayered Vertical Cross-Sections

The use of spreadsheets in numerical groundwater flow modeling, although not new, has yet to be fully exploited in educational settings. This teaching aid complements the one published earlier, broadening its scope from the numerical solution for a single-layer confined aquifer to include unconfined aquifers. It covers flow in horizontal layers and multilayered vertical cross-sections. The new spreadsheets can also handle hydraulic conductivity anisotropy, provided its principal directions align with the Cartesian axes. It can also manage irregular aquifer shapes, incorporate all three types of boundary conditions, and account for pumping and recharge in the modeling process. However, the flow regime remains at steady state. With the integration of these new features, the spreadsheet model becomes a versatile tool for simulating a great number of steady-state groundwater flow situations. This user-friendly platform enables students to swiftly experiment with diverse configurations, delve into the underlying mathematical expressions, and gain insight into the workings of more sophisticated numerical codes like MODFLOW. As a complement, and for verification purposes, Python Flopy scripts are provided for all examples in the GitHub repository where the spreadsheets can be accessed.