Substantial increase in abrupt shifts between drought and flood events in China based on observations and model simulations

Yuqing Zhang; Qinglong You; Safi Ullah; Changchun Chen; Liucheng Shen; Zhu Liu

doi:10.1016/j.scitotenv.2023.162822

Substantial increase in abrupt shifts between drought and flood events in China based on observations and model simulations

Sci Total Environ. 2023 Jun 10:876:162822. doi: 10.1016/j.scitotenv.2023.162822. Epub 2023 Mar 14.

Authors

Yuqing Zhang¹, Qinglong You², Safi Ullah³, Changchun Chen⁴, Liucheng Shen⁵, Zhu Liu³

Affiliations

¹ Department of Atmospheric and Oceanic Sciences & Institute of Atmospheric Sciences, Fudan University, Shanghai 200433, China; School of Urban and Environmental Sciences, Huaiyin Normal University, Huai'an 223300, China. Electronic address: geonuist@foxmail.com.
² Department of Atmospheric and Oceanic Sciences & Institute of Atmospheric Sciences, Fudan University, Shanghai 200433, China; CMA-FDU Joint Laboratory of Marine Meteorology, Shanghai 200438, China. Electronic address: qlyou@fudan.edu.cn.
³ Department of Atmospheric and Oceanic Sciences & Institute of Atmospheric Sciences, Fudan University, Shanghai 200433, China.
⁴ School of Geographical Sciences, Nanjing University of Information Science and Technology (NUIST), Nanjing 210044, China.
⁵ School of Environmental and Geographical Sciences, Shanghai Normal University, Shanghai 200234, China.

PMID: 36921874
DOI: 10.1016/j.scitotenv.2023.162822

Abstract

Drought-flood abrupt alternation (DFAA) refers to the rapid transformation between droughts and floods, posing serious threats to ecological security, food production, and human safety. Previous studies have insufficiently investigated DFAA events at large regional scales using high-resolution observations and model simulations. In this study, the standardized precipitation evapotranspiration index was used to construct the DFAA magnitude index, which considers the asymmetric effects of drought and flood alternations. Four types of DFAA events were then investigated using high-resolution station observations and NEX-GDDP-CMIP6 model simulations. The results showed that hotspot areas of drought-flood and flood-drought alternation events were mainly in the northern and eastern parts of China, while the hotspot areas of drought-flood-drought and flood-drought-flood alternation events were obviously smaller than those of drought-flood and flood-drought alternation events. Drought-flood, flood-drought, and drought-flood-drought alternation events showed significant upward trends at rates of 0.075, 0.057, and 0.051 events/decade, respectively, and these increases were attributed to significant increases in moderate, severe, and extreme events across China during 1981-2020. Generally, the total number of DFAA events above moderate grade in the northern, central, and some areas in the southern parts of China increased obviously (>50 %) during 2001-2020 compared to 1981-2000. NEX-GDDP-CMIP6 can reasonably represent the multi-year averages and long-term trends of precipitation, temperature, and DFAA events in China. Except for the flood-drought-flood alternation events, the other three types of DFAA events showed significant increasing trends in the future, with higher rates under the SSP585 scenario than under the SSP245 scenario (e.g., drought-flood alternation events at rates of 0.033 and 0.046 events/decade under SSP245 and SSP585, respectively, during 1981-2100). DFAA events above the moderate grade were predicted to increase significantly in both 2032-2065 and 2066-2099 compared to 1981-2014, especially in northern China for the 2066-2099 under the SSP585 scenario.

Keywords: China; Drought-flood abrupt alternation (DFAA); NEX-GDDP-CMIP6; SPEI.