Seepage Analysis of Earth Banks under Drawdown

The problem of transient unconfined seepage under drawdown in riverbanks and dams is solved by using a finite element procedure. An iterative procedure is employed to compute movements of the free surface caused by time wise fluctuations in the external water levels. The finite element solutions are compared with laboratory experiments on a parallel-plate viscous flow model and field observations at a section along the Mississippi River. Correlation between the numerical solutions and observations is found to be good. Consideration is given to such special requirements of numerical techniques as discretization of infinite media and various possible flow situations at discretized end boundaries. An effort is made to obtain the numerical formulations and the computer codes that yield acceptable accuracy with economy. Some projections for use of the method for design analysis are presented.