Transient drainage to partially penetrating drains in sloping aquifers

The nonlinear Boussinesq unsteady-state differential equation used for eval uating drainage of sloping lands with drains lying at a distance above the impermeable layer was solved. A combination of explicit and implicit differ ence methods was used to obtain a finite-difference solution for a lineariz ed 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 Lu thin and Guitjens and Chauhan et al. as well as the numerical solution of M oody and were found to be in reasonable agreement.