Evaluating the Impact of Nonisothermal Flow on Vadose Zone Processes in Presence of a Water Table

Although the coupled theory of heat and mass transfer movement in the unsaturated zone has been developed for a long time, the interaction between water and heat is considered mainly in the shallow vadose zone, but not commonly in deeper soil profiles. The goal of this article was to evaluate the role of soil temperature and water vapor in the water flow in the whole vadose zone in the presence of a shallow water table by using two models with and without considering these effects. Simulated water contents and recharges were compared with observation data collected at the Hanwang Hydrology and Water Resources Experimental Station in China. The atmospheric data observed at this station were used to drive the two models during a 1-year period. Results show that the nonisothermal model better represented observed data than the isothermal model. However, the isothermal model underestimated the soil water content during the dry season and overestimated it during the rainy season. Meanwhile, the isothermal model significantly overestimated the annual cumulative net recharge to groundwater and underestimated the annual cumulative evaporation from the surface layer.