In drought monitoring, due to the different surface physical characteristics of soil and vegetation, the retrieval of soil water content using optical remote sensing is affected by the vegetation coverage. Based on the spectrum reflectance of water, this paper developed a new index named USWI (Unified Soil Water Index) incorporating the affection of vegetation coverage to evaluate the soil water content accurately. Compared with the on-site rainfall and soil moisture data from CMA, the index reflects the actual contents and changes of soil water, and is especially applicable to the rapid soil water content monitoring in large areas.

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