The survey of soil AWC is expensive due to cost consuming and time-consuming.Moreover, it is probably unfeasible because of extension of study area and spatial changes of soil.

• 通过实验的方法获得土壤有效含水量数据，不仅费用高、耗时多，而且往往因为研究尺度大，土壤在空间上高度变异而不可行。