How could sediment affect flood control at the Three Gorges Dam?

Sediment accumulation is a significant concern regarding the long-term efficacy of the Three Gorges Dam as a flood-control tool. Critics argue that the buildup of sediment within the reservoir could cause water levels to rise too high, potentially reducing the dam's capacity to contain floodwaters effectively.1

The Yangtze River carries a massive amount of suspended material, estimated between 430 million and 500 million tons annually. When this sediment settles in the reservoir, it occupies space that would otherwise be available for water storage, thereby limiting the dam's ability to regulate flow during periods of heavy monsoon rains.21

Furthermore, there are concerns that the downstream environment may be adversely affected. Because the water released from the dam is largely free of its natural silt burden, it may possess increased erosive power, potentially causing the erosion of surrounding riverbanks and leading to land degradation downstream.1