近60年围填海工程影响下厦门典型海域水龄的时空变化

发布时间：2018-05-03 04:13

本文选题：水龄 + 围填海工程　；参考：《国家海洋局第三海洋研究所》2016年硕士论文

【摘要】：厦门湾位于福建省东南部,是一个半封闭型海湾,岸线曲折,地形复杂。上个世纪五十年代厦门就开始了围海造田,围垦给地方带来巨大经济利益的同时也带来了很多负面效应。近年来,厦门湾湾内水质量逐步下降,水动力环境改变,纳潮量减小,海水自净能力下降,这些环境问题为将来地方经济的和谐持续发展埋下了隐患。环境流体动力学模型(EFDC)集水动力模块、泥沙输运模块、污染物运移模块和水质预测模块于一体,可以用于河流、湖泊、水库、湿地和近岸海域一维、二维和三维物理和化学过程的模拟。为了研究岛屿多、岸线地形及流态复杂的九龙江口-厦门湾水动力过程,本文将EFDC模型运用于该水域三维潮流及盐度场的数值模拟。对比实测资料校核了模型参数,利用实测潮位、流速和盐度数据对模拟结果进行了充分的验证,吻合度高。该水域属于规则半日潮类型,平均涨、落潮历时约6 h;潮流以往复流运动为主,表层流速最大可达2m/s;低平潮前后出现面积合计约74km2的多处露滩;发现河口区分层及不同类型的盐度锋现象均在低潮后1h时最显著。结果表明:该模式成功复演了九龙江口-厦门湾潮汐潮流和盐度场的时空变化过程,适用于模拟和分析河口及近海海域的水动力场。水体微团在空间某点的“水龄”定义为该水体微团自进入控制体以来到流经该点所需要的时间。“水龄”作为一个时间尺度变量,是表征物质交换和传输过程的重要评判指标。本文基于构建完备的九龙江口-厦门湾水域三维水动力场模型,进一步引入水龄变量,计算和揭示该水域水体年龄的空间分异特征及其在潮过程的时空变化规律,并分析其动力成因。结果表明:水平方向上,厦门湾水体年龄呈“西北高、东南低”的格局,水龄从外海向湾顶递增,由大、小金门海域的10~30天增加至同安湾顶的80~90天。湾内等水龄线大体上与潮波的入射方向相垂直,并随潮进退,但幅度不大。九龙江河口区由于受上游淡水注入和外海潮汐的影响,水龄呈“两端低、中间高”的特征,总体上介于10~25天之间,而在河口区及其邻近水域,存在一高龄水团(平均水龄为20天),该水团随涨落潮在河口区域往复运动;在垂向上,该水域的水龄分层过程受河口盐水楔锋面、咸-淡水剪切锋面及局域地形的控制,本文进一步揭示其成因。与此同时,该区域一些特殊的水体流态首次通过水龄的计算而得以明确表征,水龄概念的引入及水龄模型的应用有助于理解河口-近海复杂的水动力环境。基于九龙江口-厦门湾三维水动力-水龄耦合模型,本文最后根据厦门海域近60年来实际的岸线变化,设计了一系列的数值模拟实验,对研究区域各代表年代(1955年、1956年、1970年、1984年、2003年、2012年)的水动力和水龄进行全面的模拟,统计和分析了厦门同安湾在各代表年代的水龄大小及其分布特征,通过“水龄”的分布特征及其时空变化过程来揭示和量化围填海工程对该海域水动力(水交换)环境的累积影响。结果表明:近60年来厦门海域的围填海工程对同安湾水动力环境的影响很大,1955年以前,天然岸线条件下同安湾的平均水龄仅为57.19天,高集海堤、丙洲和东坑湾海域的围垦造成同安湾水龄剧增,1984年至2012年,同安湾的平均水龄保持在120天左右的高龄阶段,湾内水动力条件很差。
[Abstract]:Xiamen Bay is located in the southeast of Fujian province. It is a 1.5 closed Bay. The coastline is tortuous and the terrain is complex. In the 50s of last century Xiamen began to make fields around the sea, which brought great economic benefits to the place, but also brought many negative effects. In recent years, the water quality of the Gulf of Xiamen declined gradually, the hydrodynamic environment changed, and the tide was loaded. The environmental fluid dynamics model (EFDC), a sediment transport module, a sediment transport module, a pollutant transport module and a water quality prediction module, can be used in one dimension of rivers, lakes, reservoirs, wetlands and coastal waters, two The EFDC model is applied to the numerical simulation of the three dimensional tidal current and salinity field in this water area. The model parameters are checked by comparing the measured data, and the measured tidal level, velocity and salinity data are simulated by the measured data. The results have been fully verified with high consistency. The water area belongs to the regular semidiurnal tide type, the average rises, and the ebb time is about 6 h. The current reflow movement is mainly, the maximum surface velocity is up to 2m/s, and the area of the low tide is about 74km2 of about 74km2. It is found that the estuarine differentiation layer and the different types of salinity front are both 1h after the low tide. The results show that the model successfully reacts the spatio-temporal change process of tidal currents and salinity fields in the Kowloon estuary Xiamen Bay, which is suitable for simulating and analyzing the hydrodynamic fields in the estuaries and offshore waters. The water age of a water body at a certain point in the space is defined as the self entering control body of the water body to come to the need of the flow. As a time scale variable, "water age" is an important evaluation index for the characterization of material exchange and transmission process. Based on the construction of a complete 3D hydrodynamic field model in the waters of the Jiulong Estuary - Xiamen Bay, this paper further introduces the age of water age to calculate and reveal the spatial differentiation characteristics of the age of the water body and the time and space in the tide process. In the horizontal direction, the water age of Xiamen Bay is in the "northwest high, the southeast low" pattern. The water age increases from the sea to the top of the Bay, from the 10~30 days in the big and small Jinmen sea to the 80~90 days at the top of the bay. The water age line in the bay is generally perpendicular to the direction of the wave incident, and it goes with the tide. But the amplitude is not significant. Nine in Longjiang estuary area, due to the influence of the upstream fresh water injection and the tide of the sea, the age of water is characterized by "low ends and high middle", generally between 10~25 days. In the estuarine area and its adjacent waters, there is a high age water mass (the average age of water is 20 days). The water mass moves along with the rising and falling tide in the estuary area; in vertical direction, the water mass is vertical. The water age stratification process in the water area is controlled by the saltwater wedge front, the salty fresh water shear front and the local terrain. At the same time, some special water flow patterns in the region are clearly characterized by the calculation of the age of water. The introduction of the age of water age and the application of the age model of the water are helpful to understand the river. Based on the three-dimensional hydrodynamic and water age coupling model of the Jiulong River Estuary Xiamen Bay, this paper finally designs a series of numerical simulation experiments based on the actual coastline changes in the Xiamen sea area for the last 60 years, and the hydrodynamic and water of the study of the regional representative years (1955, 1956, 1970, 1984, 2003, 2012). The age size and distribution characteristics of the water age of Tongan Bay in Xiamen are statistically analyzed, and the distribution characteristics of "water age" and its spatio-temporal change process are used to reveal and quantify the cumulative effect of the reclamation project on the hydrodynamics (water exchange) environment in the sea area. The results show that the confining of Xiamen sea area in the last 60 years The sea engineering has a great influence on the hydrodynamic environment of Tongan Bay. Before 1955, the average water age of Tongan Bay was only 57.19 days under the natural shoreline condition. The reclamation of the high collection sea embankment and the reclamation of the sea area in the coast of the mainland of China and the East Keng Bay caused a dramatic increase in the water age of Tongan Bay. From 1984 to 2012, the average water age of Tongan Bay remained at the age of 120 days or so, and the water power bar in the Bay was in the bay. It's a bad piece.

【学位授予单位】：国家海洋局第三海洋研究所
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P753;P731

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