基于MIKE21模型的入海排污口对澳门近岸海域水质影响分析

Analysis of the Impact of Sewage Outfall on the Water Quality of Coastal Waters of Macao Based on MIKE21 Model

采用MIKE21模型中的水动力模块(HD)和传输扩散模块(TR)模拟澳门氹仔岛某污水处理厂入海排污口对附近伶仃洋海域水质变化的影响;通过珠江河口区一、二维联解整体潮流模型,为工程局部二维潮流模型(由MIKE21搭建)提供边界条件。选取COD Cr(化学需氧量)、SS(总悬浮固体)和NH 3-N(氨氮)3项评价因子,在“2005·6”大洪水组合和“2001·2”枯水组合为最不利水文条件下,模拟正常排放及事故排放下排污口污染物扩散影响情况。在设计达标正常排放时,水域主干道水质可满足GB 3097-1997《海水水质标准》Ⅲ类标准,事故排放若做好防范措施,造成水质超标的区域小于0.2 km^(2)。模型对入海污染物在澳门近岸海域扩散模拟具有良好的适应性,可较好模拟在海洋潮汐作用下污水排放对海域水质的影响,可作为入海排污口设置论证的依据和研究方向。

This paper simulates the impact of the sewage outfall of the Macao Taipa Wastewater Treatment Plant on the water quality changes in the nearby Lingding Ocean by the hydrodynamic module(HD)and the transmission diffusion module(TR)of the MIKE21 model,provides the boundary conditions for the local two-dimensional tidal current model(built by MIKE21)through the one and two-dimensional integrated tidal current model of the Pearl River Estuary area,and analyzes the impact of pollutant diffusion under normal discharge and accident discharge in terms of the three evaluation factors,namely COD Cr(chemical oxygen demand),SS(total suspended solids)and NH 3-N(Ammonia-Nitrogen),under the“2005·6”flood combination and“2001·2”low water combination as the most unfavorable hydrological conditions.The results show that the water quality of main channel can meet the ClassⅢstandard among the Sea Water Quality Standards(GB 3097—1997).With proper preventive measure,the out-of-limit water area under accidental discharge is less than 0.2 km^(2).This model has good adaptability to the simulation of the diffusion of pollutants into the coastal waters of Macao,so it can better simulate the impact of sewage discharge on the water quality of the sea under the action of ocean tides,and serve as a basis and research direction for the establishment of sewage outfall.