Unconfined Transient Seepage in Sloping Banks

A finite difference scheme is used for the problem of unsteady flow with arbitrary variations in water levels in nonhomogeneous and anisotropic porous soils. The solutions are obtained by using the finite difference scheme for an approximate nonlinear and the linearized version of the free surface equation of flow. The phreatic surface at any time level is located by satisfying the special boundary condition at that surface. A special iterative scheme is employed to locate the point of exit of the phreatic surface at the entrance face. Numerical solutions are compared with experimental results with a large parallel-plate viscous flow model. Good agreement is obtained between the two results. A flow net is constructed for typical numerical results to indicate their application for field problems. On the basis of good comparisons, it is concluded that the proposed numerical method can be employed for the location of the free surface in riverbanks and embankments subjected to transient flow conditions.