Field assessments of the water redistribution process are time consuming and costly because hydraulic soil properties vary extensively in space and time. The present work proposes two analytical models to estimate the dynamics of this process, based on the use of the hydraulic unit potential gradient of Richard's equation. The first model estimates the soil water content and the second flow density, both as functions of time for internal drainage at a given depth. From statistical and physical points of view, there was agreement between the model and the measured values of water content and flow density at different depths during the drainage phase of a morphologically homogeneous beach sand. The only input required by the proposed models are the data of water retention and soil hydraulic conductivity at a given depth.
soil water redistribution; Richard's equation; analytical models
