Author(s): Jiao Jian; Ding Lei; Dou Xiping; Yang Xiaoyu; Wang Yifei

Linked Author(s):

Keywords: Discharge and Sediment Load Changes; Hysteresis; River Bed Volume; Response Law; South Branch of the Yangtze Estuary

Abstract: In recent years, the sediment load in the middle and lower reaches of the Yangtze River decrease continuously. Its effect on river bed erosion has gradually been reflected in the Yangtze Estuary. However, there is a lack of quantitative research on the variation characteristics of riverbed volume in the Yangtze Estuary. Furthermore, the spatiotemporal response to the decrease in sediment load is not clear. The discharge and sediment concentration of Datong Station and Xuliujing Station of the Yangtze River are analyzed. The time-dependent characteristics of river bed volume under different elevations were analyzed. The relationship between riverbed volume at different elevations and upstream sediment discharge was established. The results show that the annual sediment transport volume of Datong Station from 2003 to 2020 is significantly reduced compared to the period before the completion of the Three Gorges Project, which has a direct and significant impact on the sediment concentration of the Xuliujing Station during the flood season. The riverbed below 0m in the South Branch of the Yangtze Estuary is in a state of scouring and the riverbed scour rate has increased significantly after 2003. Among them, the erosion of the deep groove below -10m contributes the most. The riverbed volume of the main ebb channel in the South Branch has a significant correlation with the average incoming sediment volume of Datong in the previous year. Therefore, the decrease in sediment flux mainly caused the increase in the volume of the ebb channel bed in the Yangtze Estuary. Furthermore, the effect has a hysteresis of about one year.

DOI: https://doi.org/10.3850/iahr-hic2483430201-420

Year: 2024