摘要
长江口作为上海市主要水源地,取水安全常受咸潮入侵威胁。为探究保障取水有效举措,应用MIKE21软件构建了长江口二维水盐耦合数值模型,结合实例设计了双因素梯级补水方案,通过对比不同补水策略下的环境响应变化量,对压咸效益进行综合评估。结果表明:梯级补水方案下,北港等盐度线向外海后退约为3.04~3.18 km/(10~3 m^(3)/s),南港约为3.5~3.84 km/(10~3m^(3)/s),陈行、青草沙水库水体盐度存在递减规律,衰减率大致为0.06‰/(10~3 m^(3)/s)和0.1‰/(10~3 m^(3)/s),且与补水流量基本呈线性相关;可取水窗口期时长与补水时长趋于非线性关系,表现出一定的边际效益,模拟结果显示补水流量在9 900 m^(3)/s水平下,维持13 d有望获得较优的取水效益;长江口杭州湾登陆台风倾向于对北港及青草沙水库补水效应产生显著干扰。该研究成果可为枯季极端工况下补水调度决策提供技术支撑。
[Objective]To safeguard freshwater intake security in the Yangtze River Estuary against frequent saltwater intrusion,this study aims to identify an optimal freshwater replenishment scheme that balances saltwater suppression effectiveness with water resource utilization efficiency.[Methods]To address extreme saltwater intrusion resulting from the combined effects of low runoff and strong tidal dynamics,a two-dimensional coupled hydrodynamic and salinity transport model was developed.Numerical scenarios incorporating various replenishment discharges and durations were designed based on actual dispatch strategies.Key evaluation indicators included the spatiotemporal distribution of salinity isolines and the duration of the available water intake window.The effectiveness of saltwater suppression was comprehensively evaluated by quantifying the variations in environmental responses under different replenishment strategies.[Results]Simulation results indicated that,influenced by the complex topography of the Yangtze River Estuary,the spatial distribution of replenishment effects exhibited non-uniform characteristics.Under cascade replenishment schemes,the seaward retreat rate of salinity isohalines was approximately 1.52-1.59 km/(500 m^(3)/s)in the North Channel and 1.75-1.92 km/(500 m^(3)/s)in the South Channel.Salinity levels at the intakes of Chenhang Reservoir and Qingcaosha Reservoir showed an overall decreasing trend,with decay rates of approximately 0.03‰/(500 m^(3)/s)and 0.05‰/(500 m^(3)/s),respectively.Intake salinity exhibited an approximately linear relationship with replenishment discharge,with the Qingcaosha Reservoir demonstrating a relatively higher degree of responsiveness.In contrast,the relationship between the available water intake window and the replenishment duration was non-linear,exhibiting characteristics of marginal utility.The findings suggested that maintaining a replenishment discharge of approximately 9900 m^(3)/s might provide strong assurance for water intake,while a replenishment duration of around 13 days was likely to achieve optimal benefits.Furthermore,strong offshore winds tended to amplify frontal saltwater intrusion in the North Channel.[Conclusion]Increasing discharge from the Three Gorges Reservoir effectively suppresses saltwater intrusion and contributes positively to mitigating salinity hazards in the Yangtze River Estuary.However,replenishment performance is constrained by multiple factors,including the replenishment mechanisms and offshore wind fields.Optimization of replenishment strategies should consider both discharge magnitude and duration,as prolonged duration does not necessarily result in proportional benefits.Moreover,compared with the North Branch and South Channel,replenishment effects in the North Channel and at Qingcaosha Reservoir are more susceptible to wind field influences.These findings provide technical support for decision-making on water replenishment scheduling during extreme dry seasons.
作者
张行南
蒋晓雯
吴碧琼
曹辉
曾志强
张文婷
张增信
ZHANG Xing-nan;JIANG Xiao-wen;WU Bi-qiong;CAO Hui;ZENG Zhi-qiang;ZHANG Wen-ting;ZHANG Zeng-xin(College of Hydrology and Water Resources,Hohai University,Nanjing 210098,China;China Three Gorges Corporation,Yichang 443133,China;Hubei Key Laboratory of Intelligent Yangtze and Hydroelectric Science,China Yangtze Power Co.,Ltd.,Yichang 443000,China)
出处
《长江科学院院报》
北大核心
2026年第4期34-44,共11页
Journal of Changjiang River Scientific Research Institute
基金
中国长江电力有限公司委托项目(Z242302054)。
关键词
咸潮入侵
MIKE21软件
二维水盐耦合数值模型
水动力模拟效应
压咸补淡效益
长江口
saltwater intrusion
MIKE21
two-dimensional water-salt transport model
hydrodynamic simulation
preventing saline water intrusion and storing fresh water
Yangtze River Estuary
