How do Dongting Lake and Lake Poyang affect the Yangtze River's water levels?

Dongting Lake and Lake Poyang act as vital natural retention reservoirs that help regulate the Yangtze River's water levels.12

During the flood season (June to October), these lakes receive excess water from the Yangtze, which helps mitigate downstream flooding. Conversely, from October to April, the lakes discharge stored water back into the river, which helps maintain water levels during the dry season.12

The regulatory capacity of these lakes is significant, as runoff from their respective basins accounts for approximately two-fifths of the total water volume delivered to the mouth of the Yangtze. While Dongting Lake has been supplemented by artificial retention basins and floodgates to enhance its flood-control role, Lake Poyang functions primarily as a natural system without such artificial infrastructure. Over time, both lakes have experienced changes in their regulatory effectiveness due to factors like silting and land reclamation, prompting ongoing government efforts in soil conservation and bank reinforcement to preserve their critical hydrological functions.312