三门湾2003-2013年间围涂工程对水动力环境的影响研究

摘要

三门湾位于浙江沿海中部,为半封闭式海湾,发育着多条淤泥质舌状滩地,其间又存在着具有良好水深的港汊.这种滩、汊相间的形态构成了浙闽海岸特有的一种港湾淤泥质海岸地貌.大面积的滩涂为围海造地提供了条件.进入新千年以来,三门湾内围涂速度明显加快,其对水动力环境的累积影响也逐渐增大.本文利用2003、2013年两个年份的高分辨率水深地形和岸线资料,基于Delft3D建立数值模型,以此研究十年间水动力环境对围涂工程的响应,为资源可持续利用提供参考.计算结果表明:十年间围涂缩减了湾内滩涂面积,使纳潮量减小可达近7％;纳潮量的减小,使湾内落潮流优势整体减弱,但对涨潮流的影响相对较小;围涂工程还使得湾内的潮差略有增加;粒子追踪试验结果显示,不同释放位置对轨迹变化影响较大,会对湾内外的物质交换产生影响.%Sanmenwan Bay,located in the middle of Zhejiang coast,is a semi-enclosed bay which develops a number of muddy tongue-shape shoal with branching streams in good water depth.The shoal and inlet morphology forms a particular coastal landform in the coastal area of Zhejiang and Fujian Province.As large scaled shoals opened the way for reclamation,reclamation projects significantly increased in Sanmenwan Bay since 2000,with gradually increased cumulative effects on hydrodynamic environment.In this study,high resolution depth and coastal data in 2003 and 2013 were used to establish a numerical model,and hydrodynamics responses to reclamation projects during the 10 years were evaluated.The results indicated that the tidal prism was reduced by nearly 7％ during the 10-year period,which significantly weakened the overall flood current advantage while only slight impact was observed on ebb current.It was also showed that reclamation projects slightly increased tidal range.Besides,buoy tracking test results suggested that release location had great influence on trajectory change,as well as the exchange of substances inside and outside the Bay.