Abstract:
Affected by global climate change and human activities, extreme drought events are increasingly threatening China's water resource development, utilization, management, ecosystem construction, and economic and social development. In 2022, the Yangtze River Basin experienced an abnormal phenomenon of "severe drought during the flood season" and severe drought, which significantly impacted the production, living, and ecological water use in the basin. This article analyzes the measured precipitation and water level, and drought return period in the Yangtze River basin in 2022, introducing the joint reservoir operation strategy and benefits, and summarizes the causes of this drought event. The results indicate that: ①From the analysis of rainfall, water level, and drought return periods, it can be seen that extreme drought occurred in the flood season of the Yangtze River basin in 2022. From July to October, the cumulative rainfall in the Yangtze River Basin was 291.2 mm, accounting for only 61% of the annual average value, which is the lowest in history since 1961. The water level of the main control station reached the historical extremely low value from August to October, and the monthly average water level and monthly minimum water level are significantly lower than theannual average value. The inflow of Yichang and Luoshan station from July to October 2022 is the second smallest in the same period, with return period about 30-60 year; The inflow of Hankou and Datong stations is the lowest in the same period, with return period of about 70 year. ②The joint operation of reservoir groups alleviated the trend of low water levels during dry periods. In August 2022, the controlled reservoir group replenished 8.87 billion cubic meters of water, which raised the water level of the main control stations by 0.4-1.3m, effectively slowing down the trend of water recession in the middle and lower reaches of the Yangtze River. ③ The La Nina event has provided important climatic background conditions for the occurrence and development of high temperature and drought in the Yangtze River basin since June 2022. Abnormal atmospheric circulation, long duration of low water level and high temperature, and increased demand for water use along the river have contributed to the extreme drought in the Yangtze River basin during the 2022 flood season. The research results can provide technical support for drought analysis and research in the Yangtze River basin, strengthening the unified regulation and management of water resources, and effectively improve drought response capabilities.