白洋淀水循环特点及其对生态环境的影响

在理想假设下,利用MITgcm模式研究了风对白洋淀内水体循环流动的影响。研究指出:(1)风应力可看作是水体循环的主要驱动力;(2)在风应力的作用下,水体表层的流动主方向与风的方向一致,下层水体的流动方向与表层方向相逆或近似相逆;(3)表层以下水体流动复杂,次表层水平流动有明显的双漩涡结构;(4)淀底地形对水体垂向流动影响很大,垂向速度变化复杂,垂向上有双涡流动现象,靠近岸边多有上升流和下降流;(5)淀内水体流动沿着水平和垂向两个方向流动,在冬季和夏季流向相反。在分析以上流动特点的基础上,讨论了流动对各个不同子区域的生态环境可能造成的影响:I区域是一个相对独立的水体区域,该区域内的水体污染物自成系统,与外界交换较少。而对A、B、C、D四个区域内的污染物分布等要统一考虑,四个区域内的水体交换,可看作是一个统一的整体。E、F区域内的水体流动受到上述A、B、C、D四区内双涡流动的影响,但在这两个区域靠近岸边有强烈的上升流和下降流,有可能使得污染物的分布更加复杂。G、H水深很浅,水流速度缓慢,受到污染后污染物不易扩散。

THE WIND-DRIVEN WATER CIRCULATION IN BAIYANG LAKE, CHINA AND THE IMPLICATION TO ENVIRONMENTAL REMEDIATION

The distribution and influence of wind stress on the water circulation in Baiyang Lake was simu-lated with MITgcm model. The results show that wind stress was the main driving force on the water circulation,as the water of surface layer moved in wind direction,while in underneath deeper layers,it was reversal or nearly reversal to the upper one's in more complex circulation pattern. Double eddies were clearly shown in the second horizontal layer. The topography of lake bottom complicated further the patterns of vertical flow with double ed-dies. In overall,the lake water circulation was in two directions,horizontal and vertical,regardless of seasonal change. In specific,Area I was an isolated area with stagnant water,while open Areas A,B,C,and D should be treated as a whole in terms of water exchange when pollution is studied. In Area E and F,water circulation was affected by the double-eddy in above-mentioned four areas,and by additional upward and downward flows near lake bank,which made the pollutant distribution more complicated. In shallow Areas G and H,slow-moving water would hold contaminant from dilution. Understanding in detail the circulation in the lake will help protect local environment and ecosystem from pollution and deploy remediation implementation.