长江潮汐河段汊道相对稳定性及河势联动机理研究

The main stream of tidal river reaches frequently oscillates between the branches, forming interconnected branching reaches in a lotus-root shape. These branches have poor stability and high connectivity of river potential between the upper and lower reaches, making navigation and river potential conditions extremely unstable and restricting waterway navigation in multibranching tidal river reaches. Therefore, these reaches are the main focus both in China and other countries for waterway navigation in rivers and river channel regulation. Using the tidal reaches at the lower Yangtze river as examples, we use different research methods, including field-measured data analysis, mathematical modeling, and logical analysis to study the effects of variations in tidal runoff hydrodynamics on the range of fluctuations of tidal current, branch diversion ratio, branch morphology, the pattern of beaches and trenches, and the evolution of lateral and channel bars. Furthermore, we analyze the relative branch stability and intensity of river potential connectivity between the upper and lower reaches. It is expected that the internal mechanism of tidal runoff hydrodynamics in the evolution of lateral and channel bars and development and maintenance of reach branching will be determined and a quantitative index for evaluating the relationship between the relative branch stability of tidal reaches and river potential connectivities will be established. The results of this study are expected to supplement the existing theories on the evolution of riverbeds in tidal reaches. This study provides a theoretical background for tidal river channel regulation, construction, the maintenance of waterway regulation projects, dredging maintenance, as well as the planning of waterway regulation projects.

潮汐河段主流摆动频繁，塑造了藕节型连续分汊的河道形态，其汊道稳定性差且上下游河势联动性强，使得通航及河势条件极不稳定，制约着潮汐河段多汊通航目标的实现，是国内外通航河流河道与航道治理的重点河段。本项目以长江下游潮汐河段为例，采用实测资料分析、数学模型和理论分析等研究方法及手段，开展径潮流水动力变化对潮流界变动范围、汊道分流比、汊道形态、滩槽格局及边心滩演变等影响研究，分析汊道相对稳定性和上下游河势联动性强弱。预期揭示径潮流水动力在边心滩演变、汊道发育与维持中的内在机理，建立潮汐河段汊道相对稳定性和河势联动性量化评价指标方法。预期取得的研究成果，在理论上可丰富潮汐河段河床演变学研究内容，工程实践上可为潮汐河段河道治理，航道整治工程规划、建设与养护、疏浚维护等提供理论支撑。

潮汐河段的主流摆动频繁，塑造了藕节型连续分汊的河道形态，其汊道稳定性差且上下游河势联动性强，使得通航及河势条件极不稳定。准确把握历史时期及近期河道、航道演变规律，是河势控制与航道整治工程取得预期效果的前提，只有摸清其调整的成因，其整治措施才更有针对性，治理效果才能事半功倍。本项目以长江下游潮汐河段为研究对象，开展径潮流水动力变化对潮流界变动范围、分流比、汊道形态、滩槽格局及边心滩演变等影响研究，分析汊道相对稳定性和上下游河势联动性强弱。重点解决径、潮流水动力在潮汐河段汊道发育与维持中的作用关系、潮汐分汊河段与上下游河段联动关系的定量关系。依托本项目发表SCI期刊文章6篇（TOP期刊1篇），EI期刊4篇；授权国际专利1项，进入实质审查的国际发发明专利1项，国内发明专利2项；获得省部级科学技术奖2项，出版学术著作3部。通过本项目研究，阐明了潮汐河段边心滩周期性演变规律，揭示了径潮、流水动力在汊道发育和维持中的内在机理；建立了潮汐汊道相对稳定性及河势联动性评价指标方法。