An analytical model for predicting water table dynamics during drainage and evaporation

Water table dynamics in tile-drained fields have been thoroughly investigated by numerous researchers. Recent studies have highlighted the importance of incorporating the effects of evaporation into the design of such drainage systems. In tropical areas, evaporation plays a particularly crucial role in lowering the water table in finely textured soils. In this paper, water table dynamics are investigated for the case of coupled drainage and evaporation. A simple analytical model that determines the relative contribution of the drainage component to the draw down of the water table is proposed. The modelʹs estimates compare reasonably well to field data, as well as those derived from numerical simulations conducted for various evaporation rates and soil types. When presented in a non-dimensional form, the modelʹs results can provide a quick estimate of the relative contribution of drainage to lowering the water table, which is highly relevant to the hydrology of acid sulphate soils.