Based on the equations of coupled heat-moisture anisothermal flow and the behaviors of stress-strain of unsaturated soil

an interaction model of atmosphere-unsaturated soil is established with the boundaries of actual evaporation and vegetation transpiration. The influence of climatic evaporation and vegetation transpiration on the suction and deformation of soil surface are analyzed by the interaction model. It is shown that the major governing factor for the suction and deformation of soil surface is outer climatic condition where solar net radiation and wind velocity are the most contribution

while the internal hydraulic and thermal parameters of soil property play a less role in the estimation of evaporation. With the cover of vegetation

the behavior of suction depends on the leaf area index (LAI)

while the magnitude of total evaporation and transpiration determines the deformation of soil surface.