【作者】 郑敬云；

【导师】 陈永灿；

【作者基本信息】 清华大学 ， 水利工程， 2010， 博士

【摘要】 随着经济社会的快速发展,工业化、城市化的不断推进,人增地减的矛盾日益凸现,土地资源日益紧缺,河口促淤造地成为拓展城市空间的重要载体。而河口地区的水下地形和岸线形状复杂,波浪、水流、泥沙运动共存,水动力与泥沙条件十分复杂。论文以瓯江口为例,采用海域水文泥沙环境分析、海床冲淤演变分析、波浪潮流泥沙数值模拟等方法,研究河口地区围涂开发的水环境动力特征,为河口的治理开发提供有效的分析手段,为工程的可行性论证提供有力的技术支撑。基于翔实的原始数据,论文首次分析了灵昆潜坝、灵霓北堤、温州浅滩一期围涂工程等已建工程对河口水沙环境与河床演变的综合影响,揭示了瓯江河口水动力与泥沙的本质及河口演变规律,阐释了温州浅滩二期围涂开发对河口演变的影响。研究表明:(1)河口潮流动力特征是影响其演变的主要因素,温州浅滩的走向与瓯江南、北口潮流的主方向基本一致,对其进行圈围造地将局部改变河口的潮流动力,温州浅滩二期围涂开发将使南口水域呈冲刷加强的趋势,但不会引起河口河势明显变化,围涂开发符合河口自身演变规律;(2)温州浅滩二期围涂区域总体呈冲淤动态平衡状态,开发应采取必要的工程促淤措施。基于矩形网格有限差分数值方法,论文采用波浪及其破碎作用的波浪辐射应力、波流底切应力、波流挟沙力、破波切应力来描述泥沙运动机制,构建了波浪、潮流、泥沙、底床冲淤等多因素数学模型,模拟复杂河口的水沙特性具有更强的普适性。论文紧密结合工程实际,采用数值模拟的研究手段,首次对温州浅滩二期围涂开发进行了研究。研究表明:(1)促淤区内流速普遍减小,有利于泥沙的落淤,不留缺口的方案1、预留缺口的方案2平均淤积厚度分别为0.59m、0.51m,就泥沙落淤环境与促淤效果而言,方案1略优于方案2;(2)实施温州浅滩二期围涂开发,对瓯江河口的泄洪基本上没有影响,不会明显改变河口的分流比,对港口航道没有负面影响,对沙头水道与乐清湾水域没有影响,但在工程附近水域局部冲刷明显,在实施过程中应注意采取防冲措施,防止局部冲刷的不利影响。同时,应进一步加强围涂开发对河口生态环境影响及其对策研究。更多还原

【Abstract】 It is very significant for reclamation to meet new land requirement in estuarine cities with increasing population and decreasing land due to industrialization and urbanization. Nevertheless, the process of wave propagation, tidal movement and sediment transport, which provide the basic forces for reclamation, are very complicated in an estuary with irregular bedform and coastline.This dissertation focuses on investigating the impact of reclamation in Oujiang River estuary on dynamical characteristics of the water environment, and is carried out on the basic analysis of the observed data of water-sediment environment conditions and tidal flats processes. Moreover, it also employs a numerical model to study the sediment transport under currents and waves, which supplies an effective method for complicated estuary regulation and strong technical support for feasibility demonstration of the project.Comprehensive impact of the finished projects is first examined, which include submerged dyke of Lingkun, North dam of Lingni and the first phase reclamation of Wenzhou Shoal on estuarine water-sediment environment and evolution of the topography based on the measured data. From the gotten rules, the impact of the second phase reclamation is predicted and summarized into two points. First, the dynamical characteristics of the tidal currents have vital effect on the estuary processes. The direction of Wenzhou Shoal is nearly parallel to the main flow in the North and South mouths, where the reclamation would only partly change the tidal dynamics. The second phase of the reclamation will increase the erosion in the South mouth, but won’t remarkably affect the stability of estuary conditions, which corresponds to the inner processes. Second, it is highly recommended to enhance the sediment deposition and prevent the erosion in the second phase reclamation, and is on the whole in a dynamic equilibrium state of erosion and deposition.A multifactor mathematical model is established to predict the sediment transport, which is based on a rectangular mesh and the finite difference method, and consists of a wave module, a current module, a sediment transport module and a bedform topography-change module. All the radiate force, shear force, sediment transport capability of waves and the breaking effect are taken in account. The model provides an effective numerical technique for estuarine management and estuary regulation.In addition, present work has significant practical value in engineering, and numerical model has been applied for the first time to the second phase reclamation of Wenzhou Shoal. The results are as follows: (1) Two plans have been compared: plan I and II, which is with or without gap respectively. The velocity decreases widely in the silting-promotion zone, which is conducive to the sediment deposition. In terms of hydrodynamic condition of sedimentation and slit-promoting effect, plan I with an average silty depth of 0.59m is a little better than the gapped plan II with 0.51m. (2) The flux discharge and flux rate of the North and South river mouths are barely changed by the second phase project. There is no effect on Shatou Channel and Yueqing Bay, or negative effect on the port sea-route. Furthermore, in the process of implementation more measurements should be taken to prevent erosion. At the same time, it is needed to study more about the responses of the reclamation to preserve the ecological environment in the estuary.更多还原