ABSTRACT
Precipitation is held in the soil of the earth surface at a certain humidity before the moisture evaporates, flows to the river or infiltrates into the groundwater. The water in the soil is an important part of the land water cycle (Robock A et al.,2000).With the changes of climate and environment, dynamic changes of the soil water content affect the entire ecological system. Therefore, the fluctuation of soil moisture plays an important role on weather, climate and flood disaster forecast, as well as water resources circulation research.
