An evaluation of the use of IMERG products for representing drought in a typical rocky karst region experiencing rocky desertification in Guangxi, China

Droughts are very common and threatening disasters in regions where groundwater storage is difficult. High-resolution satellite estimations such as the Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (IMERG) provide a new solution for drought monitoring in areas with this special terrain. In this study, the pre-evaluation of products is conducted before drought monitoring, then based on the Standardized Precipitation Index (SPI), the application in drought presentation is evaluated over Guangxi, a Chinese province where the karst areas are being eroded by rocky desertification. The main results are as follows: (1) The monthly estimating by IMERG products is reliable, and the best performance for daily scale appears in regions with rich rainfall and severe rocky desertification, while high errors occur in the same place. (2) IMERG products can be an alternative to gauge-based data in drought monitoring over karst rocky desertification regions like Guangxi, where multiple droughts happened from 2000 to 2017. The SPI of IMERG_F has the best spatial consistency, and better results are presented over humid rocky desertification regions.