Study on Modeling Soil Moisture Responses Under Steady-state Evaporation Conditions from a Shallow Water Table

Based on the model introduced by Gardner,the responses of soil moisture under steady-state evaporation conditions from a shallow water table for 5 different soils in Europe were numerically studied. Numerical experiments results showed that the distributions of soil water content and logarithmic absolute value of soil suction down the soil profile have a single inflexion and double inflexions,respectively. Under the same groundwater table,the maximum surface evaporation rate has negative correlativity with clay content for different soils. Two-rank polynomial could be used for modeling the relation between maximum surface evaporation rate and groundwater table. When surface evaporation rate is between 0. 01 ～ 0. 1 cm / d,the corresponding values of the maximum groundwater table could be used for the evaluation of referenced value of critical water table. Results modeled for relative evaporation rate coefficient is analogical with those of surface evaporation rate coefficient in the experiment recorded in some reference. Results predicted by the model introduced by Gardner are correct and reliable,which indicated that the simple model could be used for the responses of soil moisture under steady-state evaporation conditions from a shallow water table.