粤东后江湾近岸长重力波特征分析

利用粤东后江湾近岸有限水深(包括碎波带)4个测点的压力波数据,依据波谱分析方法对4个测点的入射波有效波高、长重力有效波高、有效波陡、波面谱、谱宽度和谱尖度参量进行了统计和对比分析.分析认为,在近岸有限水深条件下,波浪由近岸(相对水深0.201)到破、碎波带运动过程中,(1)长重力波有效波高呈增大趋势,至破、碎波带位置增幅最为明显;(2)入射波有效波高至破、碎波带区域达到最大,在破波带外有限水深区域呈现先增大后减小的变化趋势;(3)有效波陡、谱宽度参数呈增大趋势;(4)波浪内部能量向高、低频段发生转移,至破、碎波带区域转移程度最为明显,在峰值频率的高、低频段形成谱峰;长重力波谱强度在破、碎波带区域明显高于对应有限水深测点.     

长重力波形成机制研究进展

简要介绍了长重力波的概念和它在近岸过程的重要性,概述和评析了长重力波形成的Munk与Tucker模式,BLW,Unoki和非线性作用模式,BFLW模式以及BLW和BFLW联合作用等6种模式,展望了长重力波综合研究的内容和必要性.     

近岸过程与海岸侵蚀机制研究进展

首先简单介绍了砂质海岸近岸地形动力过程的时空多尺度特征及其复杂性,海岸系统相互依存的3个方面和近岸带地形动力基本特征;进而从5个方面论述了国内外对砂质海岸侵蚀地形动力过程与机制研究的进展:1)长重力波运动与海岸侵蚀;2)近岸环流、波增水、底流运动与岸滩侵蚀;3)海滩-碎波带地形动力状态与岸滩侵蚀方式;4)波生沿岸流、沿岸输沙与海岸长期变化;5)海岸侵蚀终极平衡形态规律。最后概括了未来需优先探索的地形动力学问题和研究策略。     

近岸带三组成波耦合作用的观测与分析

利用近岸带两个测点的波浪同步观测资料，通过二阶谱分析了三组成波的非线性相互作用。对波谱峰频自相互作用的二阶相干系数b^2(fp，fp）及对应的二阶位相值β(fp，fp)、最大二阶谱幅值B最大(f1，f2)和最大二阶相干系数b^2最大(f1，f2)的组成波频率分析结果表明：(1)弱频散作用的过渡水深区存在着明显的非共振三组成波耦合作用；(2)包括谱峰频在内的自相互作用是近岸区波耦合作用的重要形式；(3)随着水深减小，趋近碎波带，非线性耦合作用进一步增强，谱能量以向低频转移为主变为向高、低频两侧转移，波形趋于前倾。     

近岸波、流作用下结构物附近海岸演变的数值模拟

针对与砂质海岸在波浪作用下的演变有关的波浪、近岸流及输沙问题进行了系统的研究,并对结构物附近海岸演变进行了数值模拟。考虑了波浪折射-绕射及波浪破碎的综合作用,在近岸流场的模拟中用沿水深积分形成的K方程模型确定涡粘系数。计算岸滩地形变化时,综合波浪、近岸流作用的底沙和悬沙输沙率,并考虑波浪对泥沙作用的影响。模型对防波堤和近岸沉船附近地形变化进行了模拟,效果良好。     

具有内波特性的渤海南部次重力波

次重力波(infragravity waves)是频率范围介于局地平均Brunt-V¾is¾l¾频率和0.05Hz(涌浪频率)之间的一种海洋波动,其能量在深水大洋中一般甚低,但在浅海中却很强.该波动的研究对于浅海海洋内部混合、近岸海洋工程、海洋生态学、海洋沉积学及军事海洋学均有重要的意义.Munk[1]很早就开始研究这类波动,然而主要由于观测技术的限制,对于该类波动的动力学机制的研究进展迟缓.     

我国海岸与近岸海域综合整治势在必行

海岸与近岸海域在国民经济、国家生态安全中占有重要地位,然而近年来由于自然灾害和人类过度开发等原因,海岸与近岸海域面临巨大压力.文章在分析海岸与近岸海域的重要地位和当前面临的主要问题的基础上,着重研究探讨海岸与近岸海域综合整治的必要性和可行性.     

近岸海域波浪场中污染物运动的实验研究

通过实验模拟,研究了缓坡海岸带(坡度为1:100和1:40)波浪场中污染物的运动.给出了污染物在波浪破碎区和非破碎区运动范围的变化,讨论了在规则波和非规则波作用下波浪破碎区和非破碎区污染物运动的宏观变化趋势.     

近岸补沙养护海滩研究综述

在海平面上升、风暴频率增加等自然因素和人工挖沙、河流水利及海岸工程建设等人为因素的影响下。海滩侵蚀的现象越来越普遍。我国厦门岛、北戴河、青岛汇泉湾等黄金海滩滩面变陡,颗粒粗化,岸线萎缩,可用沙滩面积大幅减少,海滩资源的损失已成为滨海城市旅游业发展的瓶颈。     

粤东后江湾涨落潮下的碎波带波能与滩面地形时空变化分析

利用涌浪和处于陡滩面、滩面下陡坎和深槽海滩地形条件下的海滩碎波带压力波和滩面地形资料,对碎波带中的入射总波能、长重力波能及两者比值随潮位涨落的变化关系,碎波带动力因子与滩面地形之间的作用关系及典型相关和多维偏交叉谱关系等作了初步分析。结果表明,碎波带中的入射总波能与潮位涨落呈现出一致的变化规律;而碎波带中的长重力波能变化与潮位涨落变化趋势相反;碎波带各动力因子、滩面潜水位和碎波带波浪、潮位及滩面地形引起的滩面陡坎处破波点位置变动等因素的耦合作用,对滩面向海发育和滩面地形变化有重要影响。     

Infragravity Waves Produced by Wave Groups on Beaches

The generation of low frequency waves by a single or double wave groups incident upon two plane beaches with the slope of 1/40 and 1/100 is investigated experimentally and numerically. A new type of wave maker signal is used to generate the groups, allowing the bound long wave (set-down) to be included in the group. The experiments show that the low frequency wave is generated during breaking and propagation to the shoreline of the wave group. This process of generation and propagation of low frequency waves is simulated numerically by solving the short-wave averaged mass and momentum conservation equations. The computed and measured results are in good agreement. The mechanism of generation of low frequency waves in the surf zone is examined and discussed.     

基于LPB1-2型声学测波仪资料的近岸浪特征分析

为研究近岸浪的形态特征,利用LPB1-2型声学测波仪在某海域所测得的海浪数据对近岸浪特征要素进行统计分析,利用最大"熵"原理推导出了波高的最大"熵"分布,研究了状态参量对波高分布和波高"熵"的影响。研究表明,该海域的波主要以波高0.3~0.7 m,周期2.5~5.5 s的波为主,表示离散程度的特征值平均差为0.267,日极差值主要在0.1~0.4 m区间内,最大值为1.0 m,分布较为集中,波高分布近似为正态分布。     

Infragravity waves with internal wave characteristics in the south of the Bohai Sea of China

The measurements by using ADCP (500 KH) and CTD were made during August 2000 in the south (37°55''N, 120°25''E) of the Bohai Sea, where the water depth was about 16.5m. The data of horizontal velocity with sampling interval of 2 min in 7 layers were obtained. The power spec-trum analysis of these data indicates that there are very energetic infragrvity waves with a period of about 6 min. The coherence spetrum analysis and the analysis of temporal variation of shear show that these infragravity waves are mainly the free wave model (properties of edge waves), in the meantimethey possess some characteristics of internal waves, which are likely due to the distinctive marine environment in this area. It is speculated on that the instability processes (chiefly shear instability) of sheared stratified tidal flow owing to the effect of sea-floor slope in the coastal area might be the main mechanism generating these infragravity waves.     

粤东后江湾冲流带滩面高频振动及动力作用分析

利用涌浪影响下短时段内的冲流带滩面高频高程数据和碎波带波流资料,在奇异谱分析(SSA)的基础上,以比研究了不同形态滩面的冲淤变化趋势、趋势分布形状、冲淤变化周期和冲淤变化强度,以及同一条剖面不同桩点间各因素间的变化关系;用交叉谱方法探索了每分钟滩面高频冲淤变化与碎波带长重力波间的作用关系.分析结果表明,滩角韵律地形引起的冲流分流作用促进了滩脊向滩谷的泥沙转运,冲流带滩面存在明显的长重力波频段的周期性冲淤振动,滩面冲淤振动强度由滩面下部向上部递减,碎波带长重力波对滩面高频冲淤变化起重要作用.     

Modelling the effects and economics of managed realignment on the cycling and storage of nutrients, carbon and sediments in the Blackwater estuary UK

A hydrodynamic model is developed for the Blackwater estuary (UK) and used to estimate nitrate removal by denitrification. Using the model, sediment analysis and estimates of sedimentation rates, we estimate changes in estuarine denitrification and intertidal carbon and nutrient storage and associated value of habitat created under a scenario of extensive managed realignment. We then use this information, together with engineering and land costs, to conduct a cost benefit analysis of the managed realignment. This demonstrates that over a 50–100 year timescale the value of the habitat created and carbon buried is sufficient to make the large scale managed realignment cost effective. The analysis reveals that carbon and nutrient storage plus habitat creation represent major and quantifiable benefits of realignment. The methodology described here can be readily transferred to other coastal systems.     

养马岛西南海域泥沙运移及近岸演化态势研究

养马岛西南海域近30年来发生普遍淤积,海域海底淤积速率平均为1．5cm／a,局部可达10cm／a。鱼鸟河以东岸线向海推进速度约1～6m／a。海域表层沉积物有整体细化的趋势,该海域的快速淤积与海岛的屏蔽消能以及海堤的拦截作用有关。海底淤积对取水口的设计方案有明显影响,分析了工程海域动力、泥沙、海岸及近岸演化态势,并对取水口设计方案进行了论证。     

Influence of offshore topography on the amplification of infragravity oscillations within a harbor

The main purpose of this article is to systematically investigate the influence of offshore fringing reef topography on the infragravity-period harbor oscillations. The infragravity (IG) period oscillations inside an elongated harbor induced by normally-incident bichromatic wave groups are simulated using a fully nonlinear Boussinesq model, FUNWAVE 2.0. Based on an IG wave decomposition method, effects of plane reef-face slopes, reef-face profile shapes and the existence of reef ridge on bound and free IG waves and their relative components inside the harbor are comprehensively studied. For the given harbor and reef ridge, the range of the reef-face slopes and the various profile shapes studied in this paper, results show that the amplitude of the free IG waves inside the harbor increases with the increasing of the reef-face slope; while the bound IG waves inside the harbor seem insensitive to it. The effects of the profile shapes on the IG period waves inside the harbor are closely related to the width of the reef face. The existence of the reef ridge can relieve the bound IG waves to some extent when the incident short wave amplitudes are relatively large, while its effects on the free IG waves are negligible.