近70年胶州湾水动力变化的数值模拟研究

Numerical simulation of the hydrodynamic evolution of the Jiaozhou Bay in the last 70 years

采用无结构三角形网格海洋模式FVCOM,基于胶州湾不同年代的岸线和水深地形条件,建立胶州湾及其邻近海域各年代的三维潮汐潮流数值模型,从数值模拟角度分析和比较胶州湾不同年代纳潮量、潮汐潮流、水交换率等水动力参数的变化。结果表明:随着胶州湾水域总面积不断缩小,纳潮量在逐渐减小,2008年全湾的纳潮量相对于1935年减少了31.5%,约合3.9×108 m3;海湾流场结构变化很小,流速呈减小趋势;胶州湾欧拉余流"团团转"的多涡结构基本保持不变,最大值都发生在团岛附近;海湾的水交换能力趋弱,对整个胶州湾水体的半交换时间进行海湾平均,不同年代5套岸线下海湾的水体半交换时间分别是37.0d,36.7d,39.2d,39.7d和40.8d。

A three dimensional tide and tidal current system was established using unstructured triangular grids for Jiaozhou Bay,based on a Finite-Volume Coastal Ocean Model （FVCOM）. With five different sets of coastlines and water depths in different decades,we compared the hydrodynamic changes of Jiaozhou Bayincluding tidal prism,tide and tidal currents as well as water exchange rate. The model results show that the tidal prism decreases gradually with the reducing of the water area of Jiaozhou Bay. To be more specif- ic,the tidal prism in 2008 reduces by 31.5 % compared with that in 1935, which is about 3.9 × 10^8 m3. The patterns of velocity fields in different decades are similar, however the velocity decreases. The multi-vortex pattern of the Eulerian residual currents remains with small changes of their positions and sizes. The stron- gest Eulerian residual current normally appears near Tuandao. The general trend of water exchange capaci- ty is decreasing. The averaged half-exchange time is 37. 0, 36.7,39.2,39.7,40.8 d in 1935,1966,1986, 2000 and 2008, respectively.