The Numerical Analysis of Infiltration, Considering Hysteresis, Into a Vertical Soil Column at Equilibrium Under Gravity

Abstract

AbstractA numerical solution of the flow equation for water in soil was obtained for a flow system consisting of a vertical column of soil which had been drained from saturation to equilibrium with a water table. A thin layer of ponded water was assumed to be applied to the top end of the column. This meant that each point in the column wetted up along a different scanning curve of the moisture characteristic curves. The solution of the equation depicts the time and depth distributions of water content and pressure head during the resulting infiltration. The results show that for soils that have water content‐pressure head curves with regions of steep slopes, the wetting front advances as a steep, well‐defined front. In those soils with more gently sloping water content‐pressure head curves, the wetting front was more diffuse. If hysteresis was ignored, the position of the front at any one time was overestimated or underestimated—depending upon whether the drainage or wetting curve was used.