The impact of "flood season anti drought" on scouring and silting changes in main stream of middle and lower reaches of Changjiang River under Extreme Water Conditions

In 2022, the extreme "flood season anti drought" hydrological conditions occurred in the Changjiang river basin. And the middle and lower reaches of Changjiang River experienced the lowest water level in the flood season. This paper analyzed the scouting and silting change characteristic of the main stream of middle and lower reaches of Changjiang in 2022. The result showed that sediment discharge increases and decreases at various to June, and the overall sediment discharge is same. From July to December, sediment discharge at various stations decreases significantly. The sediment discharge from Yichang to Jiujiang is 23.91million t, the sedimentation from Hukou to Jiangyin is 46.57 million m3 (from Hukou to Datong is 12.11 million m3, from Datong to Jiangyin is 58.68 million m3), and the sediment discharge below Jiangyin is 63.35 million m3. The decrease of upstream flow and the influence of tidal level at the Changjiang Estuary are the reasons for the sedimentation from Hukou to Jiangyin. The results provide a basis and reference for further study on the variation of sediment discharge and sedimentation in the middle and lower reaches of the Changjiang River and the prediction of future sediment discharge and sedimentation trend.