Seepage design charts for flat bottom dams resting on heterogeneous media

Several researchers have developed numerical models that are capable of computing the flow in porous media by implementing the finite difference or the finite element method. In order to make an efficient use of such models, the results of flow estimates were compiled and plotted to form different sets of design charts. These design charts can be used to estimate the seepage quantity and exit gradient in heterogeneous media under flat bottom dams. A numerical model, employs the finite difference technique, was developed to solve for piezometric head and seepage velocity at all nodal locations within the permeable strata. The paper contains a description of the procedure adopted to calculate seepage quantity and exit gradient from the numerical results. The applicability and validity of the charts were examined and compared with flownets and relevant existing mathematical approximations. The present analysis yields accurate results in estimating seepage quantity and exit gradient compared with the mathematical approximation.