Spatiotemporal Variation in Catchment-scale Droughts from 1960 to 2019 Across China

Abstract

【Objective】 Drought is an abiotic stress affecting agricultural production in almost every country across the world. Understanding its spatiotemporal variation is essential to improving water management under climate change. The purpose of this paper to analyze the variation in droughts in the main catchments over the past 60 years (1960—2019) across China. 【Method】 The standardized precipitation evapotranspiration index (SPEI) was used as the drought index; the extreme-point symmetric mode decomposition (ESMD) method was used to decompose the periods and trend of the SPEI time series, from which we calculated the spatiotemporal variation in drought. 【Result】 ①The temporal changes in drought varied with sub-basins from 1960 to 2019, and the most noticeable drought increase occurred in the continental river basins, with the SPEI linear tendency rate being -0.192/10 a. ②The ESMD results showed that the drought had been in increase across China, with the first and second periodic cycles being 2.07 years and 5 years respectively. ③The average occurring frequency of mild drought, moderate drought, severe drought, extreme drought and drought was 13.5%, 10.4%, 5.5%, 2.3% and 31.8%, with their associated average intensity being 0.74, 1.23, 1.67, 1.86 and 1.18, respectively. ④ENSO was closely related to drought, while NAO did not show significant impact on drought. 【Conclusion】 Except for southeastern China, basins in other regions have seen an increase in droughts over the past 60 years.

Keywords

• drought
• spatio-temporal patterns
• spei
• china