Identification of spatiotemporal changes and driving factors of ecological drought during 1982–2024 across the mainland China

Drought caused by long-term water shortage may lead to insufficient soil moisture and a decline in groundwater, affecting plant growth and species turnover, and thereby altering the structure and function of the ecosystem. The vast majority of regions in China are facing severe ecological water shortage pressure, which poses a challenge to the health of the ecosystem and the sustainable development of the economy and society. The standardized ecological water deficit index (SEWDI) adopts the actual water consumption of vegetation to characterize the ecosystem’s water supply, and calculates the ecological water deficit (EWD) as the difference between ecological water consumption (EWC) and ecological water requirements (EWR), thereby enabling dynamic assessment of regional drought stress status. Based on the SEWDI, this study used multi-source remote sensing data to reveal the dynamic changes and driving factors of ecological drought in China from 1982 to 2024, and the following main conclusions were obtained: (1) the changing trends of ecological drought in various regions of China were different, and the drought situation has been particularly severe since 2000. Except for the Huang-Huai-Hai Plain Region (HPR) and the Middle-Lower Yangtze Plain (MYP), SEWDI showed a downward trend in the other regions, indicating that ecological drought in China generally showed an increasing trend. (2) SEWDI had two seasonal mutation points, which occurred in January 2003 (confidence interval: December 2002 to March 2003) and April 2017 (confidence interval: June 2016 to March 2018). (3) The most severe ecological drought event occurred from July 2019 to April 2020, with a duration and intensity of 10 months and 9.15, respectively. The peak of the drought occurred in February 2020 (SEWDI= –1.21). (4) From spring to winter, the mean range of the grid trend feature Z s of SEWDI was –1.12 (in winter) to 0.13 (in summer), suggesting that drought in summer showed a decreasing trend, while drought in spring, autumn and winter showed an increasing trend. (5) Under the combined influence of climate change and human activities, the three optimal variable factors driving changes in ecological drought in China were evapotranspiration, soil moisture and irrigation water. The research results aim to provide a reference for the identification of ecological drought and its driving factors, and to offer a scientific theoretical basis for China’s response to climate change and ecological environment protection. • Ecological drought refers to a water shortage in the vegetation system. • Seasonal abrupt change of ecological drought was detected in January 2003. • The typical ecological drought event occurred from July 2019 to April 2020. • The effect of evapotranspiration showed the strongest explanatory power of ecological drought.