钱塘江河口咸水入侵长历时预测和对策

对钱塘江河口咸水入侵数值预测方法进行了分析，认为对短历时（15d）可联合求解一维水流运动和氯度对流扩散方程进行预测；对长历时（半年）高强度河床淤积、天文潮的月际变化，还要耦合不平衡泥沙输移和河床变形方程的动床数学模型或基于实测资料的统计模型。在实测资料分析和氯度验证的基础上，采用所建立的长历时预报模型研究了钱塘江河口的咸水入侵，结果表明，通过新安江水库增大下泄量，采用“大潮多泄、小潮少泄”的非均匀放水的顶潮拒咸对策，可以有效减少取水口处氯度值及连续超标天数和总超标时间。预报实践表明，采用本预报模型得到的富春江电站下泄的最小流量能满足杭州市各取水口不同时期超标时间的要求。

Long-term predictions and countermeasures of saltwater intrusion in the Qiantang estuary

This paper gives a brief introduction to the predictive method for saltwater intrusion in the Qiantang estuary.For the short period(15 days),the chlorinity can be described by one-dimension convective-dispersion equation.For the long-term(the second half year),riverbed deformation equation or empirical-statistical method should be used with the movement of riverbed sedimentation and monthly change of astronomic tides taken into account.As the Qiantang estuary is the main water source of the Hangzhou City,it is crucial to predict the salinity at the intake for corresponding countermeasures.Based on the model simulation,studies were made on the increase of release discharge from the Xin’anjiang Reservoir,and investigate the possibility of chlorinity and unqualified days could be effectively decreased by applying "large discharge at flood tide,small discharge at neap tide" as principle.Field data of practice showed that the minimum discharge from the Fuchunjiang Hydropower Plant calculated by the model(having been used for 30 years) can satisfy the chlorinity qualification requirements of the intake at different times,obtaining significant socio-economic benefits by saving substantial water resources.