Location of Free Surface in Porous Media

The boundary integral equation method (BIEM) is applied to the problem of locating the free surface in both steady and unsteady flow through porous media. The method is numerical in its application and uses boundary data only. Thus, the position of the free surface can be found without solving the complete flow problem. The method can be continued to find the solution to the complete problem. It is especially efficient when the solution is desired at a limited number of points (e.g., on a failure surface in determining slope stability) or in a limited area of the flow. Examples appear in the paper in which there is a free surface and a seepage surface and in which zones of different permeability appear.