Comparison of SMMI, PDI and its applications in Shendong mining area

Soil moisture has become the dominant factor in the Shendong mining area for vegetation growth and recovery. Soil moisture monitoring index (SMMI) and the Perpendicular Drought Index (PDI) were widely used to monitor soil moisture, which were all obtained from the NIR-Red spectral space. To validate whether SMMI and PDI were all can be applied to evaluate the soil moisture conditions, SPOT-6 images on October 5, 2015 in Shendong mining area are used to calculate the SMMI and PDI over ground measuring points. The SMMI and PDI are then compared to ground-measured soil moisture data with the satellite overpass. This study concludes that the SMMI and PDI provide quite similar results for soil moisture monitoring and they are quite suitable to assess the soil moisture statue in 0-5-cm-depth. The highest correlation of R2=0.54 for the SMMI and R2=0.52 for the PDI is obtained when compared with relative soil moisture from 0 to 5 cm soil depth. It is evident from the results showing the spatial distribution of drought in Shendong mining area that the SMMI and PDI are highly accordant with landform types and underlying.