Numerical Solution of 2D Free Surface to Ditch Drains in Presence of Transient Recharge and Depth-Dependent ET in Sloping Aquifer

Water table variations between drains have been investigated by various researchers in response to transient recharge. Recent studies have shown the importance of incorporating the effect of evapotranspiration (ET) in the design of subsurface drainage systems. In arid and semi-arid regions, ET plays a crucial role in lowering the water table resulting in increased drain spacing. In this paper, a numerical solution of two-dimensional free surface flow to ditch drains is presented in presence of transient recharge and depth-dependent ET from land surface for an aquifer with sloping impermeable base. The midpoint water table variations obtained from the proposed solution compare well with experimental results as well as already existing mathematical solution. When ET from the land surface is taken into account in combination with recharge, the model results can provide accurate and reliable estimates of water table fluctuation under complex situations, which are highly related to the hydrology of waterlogged and saline soils. Copyright Springer Science+Business Media, Inc. 2006