Steady phreatic flow over a sloping semipervious layer

The present work deals with steady phreatic flow above a thin semipervious sloping layer located at some distance below ground surface and above the water table of an underlying phreatic aquifer. Cases of both upsloping and downsloping semipervious layers are studied. A uniform recharge of constant rate and a semipervious layer of finite length are considered, either with length of flow shorter than the semipervious layer or with flow bypassing its edge. For each case, linearization is applied to the nonlinear continuity equation which governs the flow. Analytical solutions are then derived for the shape of the phreatic flow wedge, the length of the wedge, and the discharge rate. These results are compared with experimental ones obtained in a Hele‐Shaw analog. A good agreement is generally found between computed and observed results. Because of the analogy which exists between a phreatic surface and an interface in a coastal aquifer, the same results can also be applied to the steady freshwater flow above an interface in an aquifer divided into two subaquifers by a sloping semipervious layer.