On the flow behaviour of unconfined dual porosity aquifers with sloping base

Abstract

The flow in an unconfined double-porosity aquifer with a sloping base is investigated and equations are developed for its description. In order to obtain a relatively simple description of the problem, similar assumptions as in Moutsopoulos (2021) have been adopted; the pressure in the unsaturated zone, especially in the fractures’ network, is considered to be atmospheric, and the Dupuit-Forchheimer approximation is invoked, reducing the dimensionality by eliminating the vertical direction. The derived equations have been linearized and solved analytically for a problem involving interaction between an inclined aquifer and an adjacent surface water body similar to the one examined by Akylas and Koussis (2007). The analytical solution has been checked against results obtained with state-of-the-art numerical codes. The agreement between the two approaches is excellent. The solution tools were used to gain insight in the influence of the aquifer's base inclination on the flow quantities.