Spatial gathering characteristics of drought in the Qinghai-Tibet Plateau

Due to climate change, drought has caused serious impacts on the eco-environment, hydrology and agriculture, and drought events in the Qinghai-Tibet Plateau (QTP) have become more severer and frequent; therefore, understanding the characteristics and variations of drought is crucial to reduce its eco-environmental and socio-economic impacts. This study used the Standardized Precipitation Evapotranspiration Index (SPEI) to identify drought and assessed its interannual changes from 1980 to 2020. Then, the Hurst exponent and intensity analysis were used to identify future drought trend and the characteristics of drought intensity. Moreover, Empirical Orthogonal Function (EOF) analysis was performed to examine the main spatial gathering characteristics. The results indicate that: 1) the QTP was becoming wetter in general, and drying places were mainly distributed in the southeast and northeast of the QTP, as well as the Qaidam Basin accounting for 27% areas of QTP. 2) The trend of wet and dry in the future in most regions would be the same as the present, only 10% of the regions would have the reverse trend. 3) The rate of wet/drought changes was faster in the 1980s and 2000s. 4) The EOF mode1 revealed a gathering distribution structure with negative values in the southeast and east of the QTP and positive values in the center and west. The west was more sensitive to the variation of dry and wet, and most areas will continue to be wet in the future. EOF mode2 and mode3 mainly indicated opposite gathering patterns of southwest-northeast and south-north. The results provide favorable evidence for policymakers to better understand and prevent drought.