The study looked at changes in water flow and sediment in the Yangtze river-lake system from 1956 to 2013. They found that sediment levels in the Yangtze River, Dongting Lake, and Poyang Lake have been decreasing significantly. The researchers also discovered regular patterns in water flow, possibly linked to climate cycles like El Niño. The Three Gorges Dam has captured a lot of sediment, leading to a major decrease in sediment downstream.