Flood control effect of the fluvial process in the middle and lower reaches of the Yangtze River

The amount of sediment discharge into the middle and lower reaches of the Yangtze River continues to decrease under the influence of multiple factors including sediment interception by reservoirs and soil and water conservation. The river channel in the middle and lower reaches of the Yangtze River is subject to long-distance and long-term scouring and siltation adjustments. The storage and discharge capacity of the river channel changes accordingly, which influences flood control in the middle and lower reaches of the Yangtze River. The changes of flood control operation of upstream reservoirs and excessive flood volume in the middle and lower reaches encountering the flood of 1954 were simulated based on the prediction of the fluvial process in the middle and lower reaches of the Yangtze River for the next decade. With the further degradation of the river channel in the middle and lower reaches of the Yangtze River, the river channel storage and discharge capacity increased. The Three Gorges Reservoir can reduce the discharge flow during flood control operations and decrease the total flood interception volume. The total excessive flood volume in the middle and lower reaches of the Yangtze River decreased, but some excessive flood volume shifted from upstream to downstream in the spatial distribution.