TRANSIENT DRAINAGE TO PARTIALLY PENETRATING DRAINS IN SLOPING AQUIFERS

The nonlinear Boussinesq unsteady-state differential equation used for evaluating drainage of sloping lands with drains lying at a distance above the impermeable layer was solved. A combination of explicit and implicit difference methods was used to obtain a finite-difference solution for a linearized system of equations of Graute-Nicolson type on two time levels, ensuring the stability of the solution. The maximum height of the water tables was obtained as a function of time for different slopes varying from 0 to 70%. Model results were compared with the available experimental solutions of Luthin and Guitjens and Chauhan et al. as well as the numerical solution of Moody and were found to be in reasonable agreement.