太湖不同湖区风浪的季节变化特征

为明晰太湖风浪的空间分布及季节变化,在湖心区设立波浪观测站,利用其记录的波浪数据证明SWAN模型能够较好地模拟太湖风浪.基于所建模型,对2013年自然风场条件下太湖不同湖区风浪季节动态进行模拟分析,结果表明:受岸线、地形和岛屿等地理因素影响,大太湖的风浪总是最强,其有效波高均值为0.523 m;而东太湖风浪最小,有效波高均值为0.305 m.受盛行风场季节变化影响,太湖春、夏季有效波高均值明显大于秋、冬季.太湖波浪的能量主要来源于风场,其有效波高随风速增大而增大,两者呈极显著正相关.而风向则可以通过改变风区长度来影响风浪生消.在偏东风作用下,太湖湖西区的风浪大于东部湖区;而受盛行于冬季的偏北风影响,太湖南部水域风浪要大于北部.同时,太湖风浪的时空分布特征是造成太湖水质参数、沉积物和水生植物空间分布差异的重要原因之一.

Changes in seasonal characteristics of wind and wave in different regions of Lake Taihu

To understand the spatial and temporal distribution of wind and wave in Lake Taihu, wave observatory was set up in the center of lake. It was found that SWAN model could simulate the waves well in Lake Taihu by using the wave data recorded. Based on the calibrated model, waves of different seasons in Lake Taihu were simulated under the natural wind conditions in 2013. The results showed that due to shoreline, topography and islands, waves in the large Taihu water always showed the strongest with the mean significant wave height of 0.523m, while waves in east Lake Taihu were the smallest with the mean significant wave height of 0.305m. The values of mean significant wave height were higher in spring and summer than in autumn and winter because of seasonal changes. Wave energy in Lake Taihu was driven mainly by wind, leading to the significant wave height increased with wind speed. A significant positive correlation was found between significant wave height and wind speed. The wind direction affected growth and extinction of waves with changing the length of wind fetch. Under the easterly wind, waves in western lake was greater than that in eastern lake; while under northerly wind in winter, waves in southern lake was greater than that in northern lake. Meanwhile, the spatial and temporal distribution of waves was one of the major reasons to form a different spatial distribution of water quality, sediment and aquatic macrophytes in Lake Taihu.