多个大型采砂工程对长江下游局部河段水流条件的影响

Influence of large-scale sand mining projects on flow conditions in the lower reaches of the Yangtze River

近年来,常在长江下游同一河段同时进行多个大型采砂工程。相对单个采砂工程,其对河道水流条件的影响更为复杂。采用平面二维水流数学模型研究了工程河段不同采砂方案下水位、流速及汊道分流比等的变化规律,并对多个采砂工程同时实施后的叠加效应进行探讨。结果表明:1)单一采砂工程对潮位和流速的影响主要局限于采砂区附近,多个采砂工程同时实施反而削减了单个工程导致的潮位及流速变幅。2)单个工程实施后,落潮分流比变化大于涨潮分流比变化,多个工程的实施对河段分流格局的叠加效应较小。3)此外,通州沙西水道采砂区工程由于位于支汊入口段,其对水流条件的影响最为明显。

In recent years,multiple large-scale sand mining projects have often been carried out simultaneously in the same river reach of the lower Yangtze River.Compared with a single sand mining project,its impact on river flow conditions is more complicated.In this paper,a two-dimensional mathematical model is used to study the changes in water level,velocity,and diversion ratio of the channel under different sand mining schemes,and the superimposed effects of multiple sand mining projects implemented simultaneously are discussed.The results show that:1)The effect of a single sand mining project on the water level and velocity is mainly limited to the vicinity of the mining area,and the simultaneous implementation of multiple sand mining projects has reduced the water level and velocity variation caused by a single project.2)After the implementation of a single project,the change of ebb tide diversion ratio is greater than that of flood tide diversion ratio,and the implementation of multiple projects has a small overlapping effect on the diversion pattern of the river section.3)In addition,Tongzhousha west waterway mining project which located at the branch entrance section has the most significant impact on water flow conditions.