The Yangtze River and Poyang Lake have a complex relationship that affects water flow, sediment exchange, and the environment. By using energy theory, researchers found that the interaction between the river and lake has changed over time, with the lake's influence increasing. The Three Gorges Reservoir has also impacted this relationship, reducing the river's effects. Floods are more likely when river flow is high and the Yangtze River is blocked, while droughts occur when river flow is low and the Yangtze River can handle the water. The construction of the Three Gorges Reservoir has made the lake area more prone to droughts in September and October.