Characteristics of channel erosion and trends in river sand resource in the Anhui section of the Yangtze River

In order to understand the characteristics of channel erosion and the trend of river sand resource in the Anhui section of the Yangtze River under the new water and sediment conditions, this study analyzed changes in the Yangtze River's sediment transport, channel erosion and deposition, and bank collapse based on hydrological and sediment data from the Anhui section of the Yangtze River, long-term hydrographic survey data, observations from bank protection projects, and monitoring data from areas prone to bank collapse. The results show that the sediment load in the Anhui section of the Yangtze River has significantly decreased, with the measured annual sediment load at the Anhui Changjiang Datong hydrological station in 2021 being 71% lower than the long-term average. The riverbed in the Anhui section of the Yangtze River has been continuously eroded, with a total erosion volume of 337.5 million cubic meters from 2016 to 2021, and an average annual erosion volume of 67.5 million cubic meters. Bank collapses in the Anhui section of the Yangtze River are accelerating, with a total length of collapsed banks reaching 418 kilometers, accounting for 37.6% of the total length of the Yangtze River banks in Anhui. The originally planned sand extraction areas have been severely eroded, with a total erosion volume of 12.971 million tons, exceeding the annual controlled extraction volume of 6.4 million tons. Based on the research results, it is suggested that the Anhui section of the Yangtze River should follow the principle of "no sand to be extracted from the riverbanks" and restrict the extraction of river sand resource until a comprehensive ban on Jiang sand extraction is implemented.