中文摘要：

Phreatic evaporation is a great lose for shallow groundwater in the Taklimakan Desert. Given soil type and groundwater table, the limiting rate of phreatic evaporation is defined as the maximum of water transferred from groundwater to soil surface per unit time, which is a key parameter and control condition for phreatic evaporation model developing. The soil water characteristic curve for the aeolian sandy soil in the Taklimakan Desert was fitted with the least square method based on the formula of soil moisture characteristics curve proposed by Van Genuchten, using observed soil moisture and soil water suction data. The unsaturated hydraulic conductivity was determined by the instantaneous profile method in situ and the calculation formula for unsaturated hydraulic conductivity was established. According to the steady flow theory, the quasi-analytical solution of limiting rate of phreatic evaporation was derived on the basis of generalization of the formula of unsaturated hydraulic conductivity. The results show that the soil moisture characteristics in the Taklimakan Desert can be well described by Van Genuchten’s formula, and the limiting rate of phreatic evaporation declines by power function with the descending of groundwater table.

英文摘要：

Phreatic evaporation is a great lose for shallow groundwater in the Taklimakan Desert. Given soil type and groundwater table, the limiting rate of phreatic evaporation is defined as the maximum of water transferred from groundwater to soil surface per unit time, which is a key parameter and control condition for phreatic evaporation model developing. The soil water characteristic curve for the aeolian sandy soil in the Taklimakan Desert was fitted with the least square method based on the formula of soil moisture characteristics curve proposed by Van Genuchten, using observed soil moisture and soil water suction data. The unsaturated hydraulic conductivity was determined by the instantaneous profile method in situ and the calculation formula for unsaturated hydraulic conductivity was established. According to the steady flow theory, the quasi-analytical solution of limiting rate of phreatic evaporation was derived on the basis of generalization of the formula of unsaturated hydraulic conductivity. The results show that the soil moisture characteristics in the Taklimakan Desert can be well described by Van Genuchten’s formula, and the limiting rate of phreatic evaporation declines by power function with the descending of groundwater table.