The paper presents exact closed-form analytical solutions describing a two-dimensional profile confined groundwater flow induced by areal recharge in a laterally bounded aquifer with anisotropic permeability, which decreases with depth. The mathematical formulation of the problem for a rectangular flow domain in terms of hydraulic head and stream function are free of the limitation of the Dupuit–Forchheimer assumption. Two different types of outflow boundary conditions associated with the aquifer discharge area, Dirichlet and Neumann, are explored. Analytical solutions with respect to stream function allow examining the distribution of recharge over depth (between contouring streamlines) for a variety of flow parameter combinations. The solutions are extended to allow the groundwater transit time distribution (TTD) to be calculated. It was found that the dependence of the transit time function on hydraulic conductivity anisotropy and depth-decay coefficients may exhibit non-monotonic behavior. The mathematical models introduced in the article are accompanied by computational simulations.
- Aquifer anisotropy
- Flow net structure
- Groundwater recharge
- Transit time distribution
- Vertical aquifer heterogeneity