The researchers studied changes in water flow and sediment in the Yangtze River over the past 50 years. They found that sediment distribution is uneven, with more sediment in the upstream and less in the downstream. The construction of the Three Gorges Reservoir has led to a decrease in sediment downstream, causing changes in sediment size and distribution. The reservoir has also affected sediment deposition in Dongting Lake. Overall, the Three Gorges Reservoir has significantly altered the flow and sediment patterns in the middle and lower parts of the Yangtze River.