长江浦口段江滩复绿对河道行洪能力的影响

Influence of environmental remediation project on the discharge capacity of the Pukou section of the Yangtze River

为分析长江浦口段江滩复绿工程对河道行洪的影响,基于MIKE21 FM建立工程区段二维水动力模型,采用Moghadam淹没植被明渠糙率公式模拟植被阻水作用,研究植被对滩面糙率的改变及对行洪阻力的影响。选取水位和流速为观测指标,分析复绿前后滩地、主槽水面线变化和流速分布变化,研究不同流量条件下,植被带对行洪影响能力的影响。结果表明,江滩复绿后,河段上游水位壅高,滩地流速减小,主槽流速增大;滩面淹没水深小于临界水深(1.3 m)时,上游壅高随流量增大而增大;滩面淹没水深大于临界水深时,上游壅高随流量增大而减小。

To analyze the influence of the environmental remediation project on the discharge capacity of the Pukou section of the Yangtze River,a two-dimensional hydrodynamic model of the engineering section was established based on MIKE21 FM.The Moghadam roughness formula for submerged vegetation in the open channel was used to simulate the water resistance of vegetation and the influence of vegetation on the floodplains roughness and flood resistance was studied.Water level and velocity were selected as the observation indexes to analyze the changes of water surface line and the velocity distributions of floodplains and main channel with and without the vegetation on floodplains.The influence of vegetation on the flood discharge capacity under different discharge conditions was studied.The results show that the vegetation causes the upstream water level to rise,the water velocity of floodplains to decrease and the water velocity of main channel to increase.When the water depth of floodplains is less than the critical water depth(1.3 m),the upstream banked up water level increases with the increase of the discharge.When the water depth of floodplains is greater than the critical water depth,the upstream banked up water level decreases with the increase of the discharge.