Quantitative and detailed spatiotemporal patterns of drought in China during 2001–2013

Investigation of spatiotemporal patterns of drought is essential to understand the mechanism and influencing factors of drought occurrence and development. Due to the differences in designation of various drought indices, it remains a great challenge to obtain an accurate result in spatiotemporal patterns investigation of drought. In this study, a quantitative drought monitoring index (i.e., Integrated Surface Drought Index, ISDI) was used to identify spatiotemporal patterns of drought and the drought variation trend at the pixel level during 2001–2013 over China. Eco-geographical regionalization was used as an evaluation unit to distinguish the ecological and climatic background of drought over the whole country. The results showed that the spatial distribution of drought intensity has a strong correlation with eco-geographical regionalization in China. The severe drought areas were mainly concentrated in sub-humid regions and semi-arid regions of medium temperate zones, and humid regions of middle subtropical zones. The regions with higher drought probabilities were most distributed in the south and north of China, while the regions in central and western China exhibited lower drought probabilities. The most obvious decreasing trend of ISDI from 2001 to 2013 was located in the northeast of China and south of the Yangtze River. This decrease in ISDI over time indicates a trend for progressive aggravation of drought severity in these areas. This study shows great promise in informing the future drought prevention measures and management policies under the background of more frequent extreme climate events.