Modelling soil water redistribution in unsaturated zone during evaporation process

Assessment of evaporation from soil surface is critical for studying soil-atmosphere interaction, and thus it is essential for many geotechnical problems, such as design of the soil cover system for hazardous waste sites, estimation of water content and suction profile in the embankment, studying soil salinization in arid and semi-arid region and so on. By utilizing exponential functions that describe the relation of hydraulic conductivity and water content on pressure head, an analytical solution of Richards' equation is derived for simulating the transient water content profile with arbitrary initial condition. Also, a series of column soil evaporation experiments were conducted under a climate control apparatus to validate the theoretical development. Good agreement between the proposed analytical solution and experimental result indicates that the analytical solution provides a reliable way to investigate the interaction of evaporation and soil water profile. Although the restricted assumptions for the solutions may limit the applicability, the solutions are relatively flexible and easy implement compared to other analytical and numerical schemes.