A UNIFORM FLOW APPROACH TO DESCRIBE PERCHED WATER TABLES IN SLOPING UNHOMOGENEOUS SOILS

Aiming at better understanding the water–content dynamics related to a decrease of hydraulic conductivity at saturation with depth within the upper soil layers, the case of infiltration at constant rate, in a sloping anisotropic soil layer of finite depth, laying on a capillary barrier, was theoretically investigated. A uniform flow approach was proposed to describe the perched water table properties and the results were generalised in a dimensionless form by means of the Buckingham Pi–theorem. The infiltration thresholds for the perched water to onset and to lead the soil to waterlogging, the position and the magnitude of the maximum pressure head, and the stream function within the saturated layer were determined for any case of monotonically decreasing conductivity at saturation with depth. Numerical simulations corroborated the theoretical results obtained for exponentially decreasing conductivity at saturation.