河流交汇水域水力特征与生态功能OACHSSCD

The river confluence serves as critical nodes connecting large river networks and their affiliated waters,acting as hubs for material transport,energy transformation,and biological aggregation and dispersal.From the hydraulic perspective,analyzing the driving mechanisms of the confluence waters on the community structure and the maintenance of biodiversity helps to better understand their ecological functions and provide theoretical foundations for the conservation of endangered aquatic species and ecosystem restoration in the Yangtze River.This paper summarized the latest research on the river confluence,and expound their hydraulic characteristics and ecological functions systematically from the perspectives of habitat heterogeneity,flow regime diversity and biodiversity of the confluence.(1)The confluence formed a physically discontinuous template composed of shallow beaches and deep pools,characterized by complex structures and high habitat heterogeneity,and can serving as vital refuges and suitable habitats for aquatic organisms;(2)The confluence featured with complex hydraulic flow patterns,where shear layers,second flows,and stratification interact with the riverbed,jointly influenced the flow regime,sediment transport and riverbed morphology within the region,as well as material transportation and energy conversion,thereby acting as key drivers of biological aggregation and dispersal;(3)The confluences sustained exceptionally high biodiversity.Factors such as habitat heterogeneity,substrate particle filtration,bioflocculation-driven aggregation,and bed shielding collectively promote the diversity and abundance of invertebrates,while abundant prey resources and energy-efficient flow conditions made these zones crucial for fish and freshwater cetaceans in terms of breeding,foraging,migration,or dispersal.The confluence performed functions of adsorption-filtration and nutrient retention effects,where diverse flow regimes aggregate numerous aquatic organisms.Additionally,the Yangtze finless porpoise captured fish which moving between upstream-downstream or tributary-lake more efficiently by taking advantage of the vortices.In conclusion,the confluences exhibited diverse geomorphic features,complex hydrodynamic characteristics and pivotal ecological functions,making them essential areas for river ecosystem conservation and biodiversity protection.