闽江下游闽清河段河道演变分析

Evolution Analysis of Minqing Channel in the Lower Reach of Minjiang River

闽清河段位于闽江下游,受水库建设、河道采砂及航道整治等人类活动影响,水沙条件变化和河床演变较为剧烈,崩岸事故频发,给沿岸人民的生产、生活等带来较大影响。依据河道实测地形资料,从河道平面、深泓线变化及河床断面形态等方面对该河段的演变特征进行了分析。结果表明:受河道两岸山体及河中丁坝群制约,闽清河段平面变化受到限制,历年来的演变以纵向的刷深为主,且刷深幅度明显;其演变受到河道形态与河床边界、水库建设、河道采砂、涉河工程建设、大洪水、支流入汇及潮汐顶托等多个因素的影响;结合演变影响因素的变化趋势,预计今后一段时期内闽清河道仍将以纵向冲刷为主,应加强涉河工程基础的守护。

Minqing channel is situated at the lower reaches of Minjiang River ,due to the construction of the reservoir , sand excavation in river courses and waterway regulation ,the changes of the flow and sediment conditions and the evolu-tion of the riverbed are relatively strong ,which causes frequent riverbank collapses .These accidents affect the livelihood of people who live along the channel .Based on the measured topographic data of Minqing channel ,the evolution charac-teristics was analysed from aspects of the overall terrain variations ,the changes in thalweg and cross-section morphology , etc .The results showed that the evolution of Minqing channel in late decades were mainly in longitudinal scour with sig-nificant depth ;the influential factors of evolution include the channel morphology and riverbed border ,the construction of the reservoir ,the sand excavation ,the near-shore projects ,the big floods ,the inflow of branches and the tidal jacking . According to the change trend of the influential factors ,it is predicted that the evolution trend of Minqing channel will still mainly be longitudinal scour over a period of time in the future ,and the foundation of the near-shore projects should be protected and reinforced .