Numerical Solution of 2D Free Surface Flow to Ditch Drains in Anisotropic Soils

A numerical solution of two-dimensional free surface flow to ditch drains in homogeneous and anisotropic soils is presented. The differential equation governing two dimensional ground-water flow in anisotropic soils is solved by the alternating direction implicit (ADI) method of finite difference. In the approach the method is modified to make it applicable for curved boundaries. This simplified approach does not involve any kind of smoothing or linearization technique. The model solutions for ditch drainage with constant replenishment and instantaneous drawdown are found to be in close agreement with the finite-difference and finite-element solutions proposed by other researchers.