An Analytical Approach for Flow Analysis in Aquifers with Spatially Varying Top Boundary

Analytical models of groundwater flow with a spatially varying elevation of a top boundary are widely used. However, a vast majority of previous analytical studies truncated the irregularly shaped top section with little to no analyses of the shortcomings of the approximate solutions for the resulting rectangles or parallelepipeds. We present an analytical approach based on a perturbation technique that treats complete domains. It is especially accurate near the top boundary, where fluid circulation is most pronounced and higher accuracy is typically needed, such as in regional or hyporheic systems flow. The approach is illustrated by analyzing flow for a Tothian unit basin.