Characteristics of sediment transport and erosion-deposition changes in the middle and lower reaches of the Changjiang River in 2022

In 2022, the Changjiang River Basin experienced an extreme hydrometeorological event characterized by drought conditions during the flood season, causing water levels in the middle and lower reaches of the Changjiang River to drop to the lowest on record for the same period. This extreme hydrological situation led to new patterns of erosion and deposition changes in these river reaches. Based on detailed monitoring data of water and sediment, as well as fixed cross-sectional data, this study conducted an in-depth analysis of the sediment transport and erosion-deposition characteristics in the main channel of the middle and lower Changjiang River under these extreme conditions in 2022. The results showed that sediment transport varied between stations from January to June, with overall stability. However, from July to December, there was a significant decline in sediment transport at all stations. Calculations based on sediment transport methods revealed that 23.91 million tonnes of sediment were eroded from the Yichang to Jiujiang section, while cross-sectional methods indicated that the Hukou to Jiangyin section experienced a deposition of 46.57 million cubic meters of sediment (with 12.11 million cubic meters of erosion from Hukou to Datong, and 58.68 million cubic meters of deposition from Datong to Jiangyin). Additionally, 63.35 million cubic meters of sediment were eroded downstream of Jiangyin. Reduced upstream inflows and tidal effects in the Changjiang River estuary were the primary causes of deposition in the Hukou to Jiangyin section. These findings provide crucial insights for further understanding the patterns of erosion and deposition in the middle and lower Changjiang River, and offer valuable references for predicting future trends.