于桥水库浮游藻类时空分布规律的数值模拟研究

Numerical simulation of algae space-time distribution of Yuqiao Reservoir

于桥水库作为天津市重要的饮用水水源地,为改善水库环境、防治水华爆发,有必要研究其浮游藻类时空分布规律.本研究的主要方法是引入可以反映影响藻类生长的多个复杂非线性因子的综合参数——藻类综合生长系数,用于表征其生长变化趋势,该综合参数作为参变量添加到动力迁移模型中的对流—扩散传导方程中求解,实现生长模型与动力迁移模型的耦合,得到的耦合模型即可达到对藻类的生长规律和动力迁移作用同时兼顾的效果.应用耦合模型对于桥水库库区藻类进行模拟预测,模拟输出的时空分布图能够直观清晰地显示库区藻类浓度偏高时期和易富集区域,模拟值与实测值的平均误差为15.4%,在可以接受范围之内.模拟结果表明该模型可用于探索藻类的生长、富集和迁移规律,并为水库防治水华采取相应措施提供科学依据.

Yuqiao Reservior is the source water for the water supply of Tiajin City. It＇s therefore very important to study the spatial and temporal pattern of algae in order to improve the water quality against algae bloom. This paper introduced a comprehensive alage growth coefficient, which could reflect the influences of multiple complex non-linear factors regarding algae growth and could be used for characterizing the growth trend. The comprehensive coefficient, as the variables, was integrated into the convection-diffusion equation of a dynamic migration model to achieve the coupling of growth model and dynamic migration model. The new model can obtain, the results, which took into account both the effects of algae growth and transportation in water. The results of the spatial and temporal distribution of algae by using this model could clearly show the high concentration period and easily enriched region. The accuracy of predication was acceptable. The results indicate that the model could be used for predicting algae grpwth, enrichment and migration. It can provide scientific evidence for preventing algae bloom and taking timely responding measles.