关键词: 非饱和土, 入渗过程, 解析解, Richards方程

Abstract: By utilizing exponential functions to describe the SWCC and the relation of hydraulic conductivity and water head, an analytical solution of Richards equation is presented for one-dimensional infiltration process in unsaturated soil. This solution can consider arbitrary initial condition, meanwhile overcome the sophisticated algorithms as in previous researches. When rainfall intensity is less than the saturated hydraulic conductivity of soil, a flux top boundary is adopted. In contrast, when the intensity is greater than saturated hydraulic conductivity, a transfer from flux boundary to water content boundary occurs at soil surface boundary. The analysis of a case study shows that initial condition not only affects the value of transient water content, but also the shapes of profiles. This analytical model can compute the soil water content at any time and any soil depth. The analytical solution is capable of figuring out the time point of water logging at the soil surface and the water content of any time and any depth, more importantly it could reveal the mechanism of infiltration and provide a check to numerical solutions.

Key words: unsaturated soil, infiltration process, analytical solution, Richards equation