The rainfall infiltration replenishment and
redistribution process in sand dune and evaporation are studied by field observation
and rainfall simulation experiment in laboratory.The result shows that the infiltration characteristic of soil varies along the depth.It may be divided into three layers: surface dry sand layer,layer affected by rainfall and stable deep layer.The infiltration rate is dependent on the rainfall intensity.The depth of infiltration is linearly related to
precipitation and rainfall intensity.The rate of wetting front advancement increases at first and then tends to decrease.It reaches a steady state at last.The precipitation with 13.4mm is the critical amount dividing the useless rainfall or rainfall for supplying groundwater.When the precipitation is more than 20mm,the evaporation quantity has a little change with the increasing of rainfall.When the precipitation is more than 50mm,the soil layer of 120cm depth can reach saturated moisture capacity through
redistribution and the water will infiltrate into deeper layer forming saturated drainage.