强潮河口围海工程对水动力环境的影响

Effects of the reclamation projects on hydrodynamic environment in a strong tide estuary

针对强潮河口边界地形复杂、岛屿众多、悬沙分布在口门以上、河段存在高含沙量浑浊带以及底沙级配分布宽的特点,给出了贴体正交曲线坐标系下非均匀悬沙、底沙数学模型的基本方程、初始条件、边界条件及动边界处理技术,对计算中经常遇到的几个关键问题提出了解决方法。计算的18个潮位站潮位过程与原型吻合良好,8个断面的46条垂线同步流速、流向过程计算值与实测值吻合较好。在此基础上,探讨了多连通域复杂边界条件下非均匀不平衡悬沙与底沙的长时期的底床变形模拟问题。以瓯江口温州浅滩围海工程为例,应用二维潮流泥沙数学模型,研究了强潮河口围海工程对水动力环境的影响问题,包括该工程引起的潮量变化、各水道流速变化及长时期的底床变形。

A 2-D tidal current and sediment mathematical model has been developed according to the characteristics of the strong tide in the Oujiang Estuary and Wenzhou Bay,with complicated boundaries, multiislands, existence of turbidity, significant difference of the size distribution of bed materials. The governing equations based on boundaryfitted grid with orthogonal curvilinear coordinate for nonuniform suspended load and bed load are introduced. The numerical solutions, initial conditions, boundary conditions, and movable boundary techniques are presented. The solutions of some problems in calculations, such as critical condition of deposition or erosion, sediment carrying capacity, and nonuniform bed load transport rate, are suggested. The calculated tidal levels are in good agreement with the measured ones in 18 tidal level stations. The calculated velocities and flow directions still fit well to the measured values among the total 52 observed synchronous vertical lines distributed in 8 cross sections. The calculated input and output tidal discharges through Huangda'ao section are rather close to those measured. And the calculated values of bed deformation in both the area from Yangfushan to the estuary outfall and the outsea area are in good agreement with the observed from 1986 to 1992. By using this model, the changes of tidal influx through the estuary, velocities in different channels and the bed changes are predicted respectively under the influence of reclamation projects in the Wenzhou shoal.