The water exchange capacity of the encircled harbor has an important influence on the water quality of the harbor basin,adding water exchange channel is an effective measure to improve it.Taking the seawall reconstruction project of Zhapo fishing port as an example,the irregular triangular mesh and finite volume method were employed,based on the research results of tidal current numerical simulation,a two-dimensional convection-diffusion model was established.The numerical simulation research of water exchange capacity before and after the expansion of Zhapo fishing port was carried out,and the half exchange period and water exchange rate of the harbor before and after the project were evaluated.The results show that the water exchange capacity of Zhapo fishing port is strong,the half-life time of water body is 129 hours before the engineering,and 104 hours after the project.After the project,the Zhouzaixia breakwater is changed into a culvert-type bridge,so that the water body exchange channel is formed between the fishing port and the offshore,the water body interaction and water body exchange capacity inside and outside the harbor basin are increased,and the corresponding water body exchange capacity is enhanced.As a comparison, two aquaculture areas outside the harbor basin have strong water exchange capacity as they are well connected with the sea,so the limit change in water exchange capacity caused by the project is reasonable.%环抱式港池的水体交换能力强弱对港池的水质有重要影响,水体交换通道是改善港池水质的有效措施.本研究以闸坡渔港防波堤改造工程为例,采用不规则三角网格和有限体积方法,在潮流数模研究成果的基础上,建立平面二维对流-扩散数学模型,开展闸坡渔港扩建前后水体交换能力数值模拟研究,评估工程前后港内水体半交换周期和水体交换率.研究结果表明,闸坡渔港的水体交换能力较强,工程前水体半交换时间为129 h,工程后闸坡渔港水体半交换时间为104 h.工程后洲仔峡防波堤被改为涵洞式桥梁,使渔港与外海形成了水体交换通道,增加了港池内外水体相互作用和水体交换量,相应的水体交换能力增强.而港池外的两个水产养殖区域由于与外海相连,水体交换能力较强,工程前后该区域水体交换能力变化不大.
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