钦州湾潮流场及污染物输运特征的数值研究

【目的】钦州港作为广西重要的港口,港口快速发展的同时带来污染物排放量的不断增加。为保证钦州湾海洋生态的可持续发展,必须深入分析钦州湾的水交换与污染物输运特征。【方法】基于2010年秋季钦州湾的调查结果,应用ECOMSED模型构建了钦州湾三维潮流与污染物(以COD为例)输运模型。潮流模型的调和常数来自俄勒冈大学的中国海潮汐模型,污染物输运模型的开边界与初始值来自于调查结果。【结果】模型结果与海流调查结果吻合较好。钦州湾平均涨潮时与平均落潮时分别为11.4h与8.7h,对应落潮流大于涨潮流;平均潮差为2.8m,最大潮差4.25m,平均纳潮量约为10.8×108 m3;钦州湾的水体交换半周期为7d,而水体交换80%的时间约为28d;钦州湾COD浓度越往北越大,越靠近湾外越小,COD逐时浓度最大值约为1.27mg·L-1;钦州湾保税港区围填海后金鼓江北端和西侧的COD浓度分别上升约20%和10%。【结论】广西钦州湾保税港区的围填海工程对金鼓江的污染物浓度分布影响较大。

Numerical Study on the Characteristics of Tidal Current Field and Pollutant Transport in Qinzhou Bay

Objective] As an important port in Guangxi, the pollutants in the Qinzhou Bay are increased gradually as the rapid development of the port.In order to keep the sustainable development of the marine ecology in Qinzhou Bay, it is necessary to research on the characteristics of water exchange and pollutant transport.Methods] A three-dimensional numerical model for tidal current and pollutant transport (in the case of COD) is constructed in this study based on the in situ observation in the fall of 2010.The tidal harmonic constants in the model are distracted from the China Sea tidal model of Oregon State University, and the initial and open boundary value in the pollutant transport model is derived from the observed results in the fall of 2010.Results] The model results are consistent with the observations.And it can be concluded that the average periods of flood and ebb tides were 11.4h and 8h, respectively, corresponding to that the tidal speed averaged in the ebb tide was larger than that in the flood tide.Additionally, the average tidal range in Qinzhou Bay was about 2.8m whereas the maximum tidal range could be up to 4.25m.And the average tidal volume was about 10.8×10⁸m³.The half cycle of the water exchange between Qinzhou Bay and outside ocean was about 7d, whereas it needed about 28d to refresh 80% water in the bay.On the other hand, the COD concentration became larger as it draw closer to the northern shore, and the maximum hourly COD concentration was about 1.27mg·L^-1.After the reclamation engineering of the bonded port in Qinzhou Bay, the COD concentration in the northern and western parts of Jingujiang Bay increased about 20% and 10%, respectively.Conclusion] The reclamation engineering of the bonded port in Qinzhou Bay of Guangxi has large effect on the distribution of pollutant concentration in Jingujiang Bay.