Synergistic evolution and attribution analysis of water-sediment in the middle and lower reaches of the Yangtze River

Study area: The Yangtze River Study focus: Climatic variation and anthropogenic factors have a far-reaching impact on the evolution of runoff and sediment in the middle and lower Yangtze River. We introduced IHA-RVA and Copula functions, and used Budyko and sediment decomposition method. Under the effect of climatic variation and anthropogenic factors, the co-evaluation system and attribution analysis of runoff and sediment change are established. This study clarified the synergistic evolution law of water-sediment. New hydrological insights for the area: We found that the interannual variation trends of sediment transport at various stations in the middle and lower reaches of the Yangtze River during the period from 1954 to 2019 were more pronounced compared to the variations in runoff. Moreover, the degree of changes in water-sediment consistency varied among these stations, with water-sediment consistency gradually recovering with an increase in distance from the upstream cascade reservoirs. Human factors contributed 52.68-74.16% to the changes in runoff and 89.40-94.15% to the changes in sediment transport. Variation of water-sediment and its con-sistency in the middle and lower reaches of the Yangtze River are mainly related to human factors. The research results can provide some assistance to decision-makers in formulating regional water-sediment regulation planning frameworks.