海南岛万泉河口海岸动态及其整治对策

通过应用沉积动力学方法计算了万泉河口口门均衡过水断面面积和沿岸输沙率．计算结果表明,波浪对万泉河口沿岸沉积物的输送起着控制作用,南北向输沙作用强烈,同时潮汐汊道目前处于不稳定阶段,口门断面的变化很大。在分析了万泉河口的自然地理条件以及基本演变规律后,还从增加纳潮量、扩大纳潮水域面积、整治沙美内海及其周边生态环境、建设导堤工程改善拦门沙的浅滩航道等方面提出了万泉河口潮汐汉道口门和航道治理的一些工程和生态措施。     

胶州湾沉积环境与潮汐汊道演化特征

研究了胶州湾沉积物输运格局，沉积速率和潮汐汊道演化特征，结果表明，胶州湾口门水道内的悬沙净输运是从湾内指向湾外，湾内水体悬沙浓度终年较低，胶州湾的泥沙来源较少，沉积速率较低。历史上的围垦活动虽造成了纳潮量的减少，但口门过水断面面积并未减小。胶州湾是一个地貌演化缓慢，口站过水断面面积小于均衡状态面积的汊道系统。今后，可应用沉积动力学等方法确定维持港口和航道资源所需的纳潮量，结合纳潮海湾的环境保护和生态建设，定量地确定胶州湾的围垦潜力。     

海南岛万泉河口博鳌潮汐汊道演变及沿岸输沙率的计算

通过收集不同时期的遥感资料,结合已往的研究,分析了海南岛万泉河口博鳌潮汐汊道演变的年际与季节性变化规律;根据实测波浪资料计算了年沿岸输沙率及沿岸输沙率的季节变化。结果表明,博鳌潮汐汊道的演变具有周期性的规律,年际特征为南、北侧沙嘴分别向口门进积、口门总体变窄;从10a以上的尺度来看,封堵口门的趋势不断被洪季时的洪水和风暴潮增水所打断。另外通过沙嘴体积变化反推了博鳌近岸的沿岸输沙率,其结果与CERC公式计算结果一致,表明此公式在博鳌岸段有较好的适用性。     

柘林湾多口门潮汐汊道动力地貌的演变

潮汐汊道是连接内湾和外海、维持港口通航和水体交换的枢纽,其演变特征是整个澙湖、海湾地貌体系研究的基础。选取典型多汊型潮汐汊道系统——柘林湾为研究对象,以实测资料和历年海图、地形图为基础,结合SELFE(semi-implicit Eulerian-Lagrangian finite-element)模型,研究多汊型潮汐汊道水动力结构、泥沙运动及自然和人类活动影响下的演变特征。结果显示,20世纪70年代澄饶大联围之前,共享柘林湾125km2纳潮水域的5个汊道同时维持稳定;围垦工程后,西侧2个汇潮口门封闭,纳潮面积减少50%,导致湾内动力减弱,韩江来沙中断,湾外浅滩冲刷,泥沙向湾内输送,30多年来三百门水道显著淤积,小金门稳定,大金门冲淤调整,小门水道淤积不稳。围垦工程后小金门水道的纳潮面积变化甚少,水动力及输沙仍为落潮占优,汊道环流发育,汊道断面冲淤微调,维持稳定;大金门汊道所控制的纳潮面积减小1/3,口门涨、落潮流速不对称性减弱,汊道冲淤调整;小门水道纳潮面积剧减一半以上,汊道延长弯曲,大金门与小门水道的环流结构加剧了该汊道的淤积和不稳定。     

建立潮汐汊道P-A关系的沉积动力学方法

在均衡状态下，潮汐汉道系统的纳潮量(P)与口门面积(A)之间存在着较稳定的关系，通常用幂函数形式来表达。计算P-A关系的传统O’Brien方法因其统计性质无法给出单一潮汐汉道的P-A关系。根据沉积动力学原理，每个潮汐汉道的P-A关系都受涨落潮历时、断面平均流速、口门形态、纳潮量、淡水径流量、沿岸毛输沙量和沉积物粒度等因素的控制，对上述因素的每一种组合，都有对应的均衡态P-A关系。作者在前人工作的基础上，尝试着建立了计算单一潮汐汊道P-A关系的沉积动力学方法，并以山东半岛月湖为算例对该方法的应用进行了讨论。结果表明，均衡态潮汐汉道的P-A关系的指数n稳定在1．15左右，而系统C的变化较大。     

海南岛港湾演变与工程建设

海南岛沿岸多港湾，主要有3种类型的潮汐汊道型港湾：（1）沙坝-泻湖型潮汐汊道港湾主要分布在东南部海岸，以三亚港最为典型。三亚港原始岸线为基岩港湾海岸，由中生代花岗岩构成。花岗岩风化泥沙充填谷地港湾连成陆地，以沙坝-泻湖体系形式逐渐堆积成海积平原。（2）港湾型潮汐汊道主要分布在海南岛西部，起源于构造断裂带的港湾。其演化的主要因素是河流及海岸侵蚀向湾内供应的沉积物以及巨大的纳潮量形成的潮流动力。消费品流及海岸供沙使纳潮水域淤积，纳潮量相应减少，同时在口门内外形成潮流三角洲（拦门沙浅滩）。（3）溺谷型潮汐汊道主要分布在海南岛北岸、东北岸。其演化过程是：古河口溺谷，沿岸输沙发育海岸沙坝，古河口溺谷逐渐淤积衰退，潮流作用形成 口门外落潮流堆积体及涨潮带入海相细粒物质，使纳潮水域进一步淤浅缩小，目前这类汊道处于发育演化的晚期，接近汊道整体的消亡。     

多汊道潮汐通道狮子洋的纳潮量计算及演变分析

以狮子洋为例探究了多汊道潮汐通道的纳潮量计算方法,验证了海湾纳潮量计算公式应用在多汊道潮汐通道系统中的可行性,分别采用基于直接观测的流量计算法和基于卫星遥感资料与实测潮位订正的公式法,计算狮子洋1999-07及2005-01的纳潮量,2种方法计算结果误差在18%之内。为进一步研究近年来狮子洋纳潮量变化及其原因,采用公式法计算了2007—2016年每年7月狮子洋纳潮量,结合1999—2011年地形演变特征,说明地形对纳潮量变化的影响。研究发现:狮子洋纳潮量具有4a的周期变化规律,变化特征表现为1999—2007年因航道整治影响,纳潮量增大约10%;2007—2012年,河势较为稳定,纳潮量继续微幅增大;2013—2016年纳潮量小幅减小。     

纽约长岛一个小型潮汐汊道的水力学与地貌动力之间的短期相互作…

为了研究潮汐通道水力学与地形变化的机制及汊道对邻近海滩的影响，我们详细观测了一个小型潮汐汊道水力学与地貌的演变过程。由于波浪输沙大于潮流冲刷，汊道的水文与地貌发生了剧烈的变化，最后在观测的第八天就座淤闭了。波浪输沙形成汊道内的浅滩，汊道口门断面面积，引起了摩擦效应加大，使汊道水流经历了由落潮为主向涨潮为主的转化过程。     

潮汐汊道A-P关系中参数C和n的控制因素

与沿岸漂砂相联系的潮汐汊道系统达到均衡态时的Ａ－Ｐ关系可表示为Ａ－ＣＰ＾ｎ。根据对Ａ－Ｐ关系的模拟，本文提出在均衡条件下ｎ值必然大于１，潮汐汊道Ａ－Ｐ关系表现出弱分形现象。其原因是对应于一定强度的沿岸漂砂较小汊道以口门宽度减小，流速增大来维持均衡关系。模拟实验还表明，参数Ｃ的大小与沿岸输砂率、淡水径流量和潮汐类型有关，这些因素对参数ｎ稍有影响。前人研究有时遇到ｎ〈１的情况，这可能是由于统计分计的某     

黄渤海沿岸潮汐汊道的P－A关系

本文计算了１５个潮汐汊道的大潮潮棱体Ｐ及平均海面下口门最小过水断面积Ａ之间的回归方程式。黄渤海沿岸潮汐汊道的天然状态下的Ｐ－Ａ关系为：Ａ＝０．０８４５Ｐ１．０２０。Ｐ与Ａ不仅具有密切的相关性，还有相当大的离散性，这主要与潮汐汊道所获取的泥沙丰度及潮汐汊道的发育阶段有关。与南海、东海沿岸Ｐ－Ａ关系的对比表明，中国海和海区Ｐ－Ａ关系中的常数Ｃ和ｎ差别不大。研究也表明，泻湖型和海湾－溺谷湾型两种潮汐汊道可求得统一的Ｐ－Ａ关系。但与滨临深水区的半环抱形海湾不同。后者主要因为没有较充裕的泥沙供应及海湾水域较为开敞，而不应列入潮汐汊道的范畴。     

Assessment of tidal inlet evolution and stability using sediment budget computations and hydraulic parameter analysis

Research into the response of coastlines to the opening and stabilisation of inlets has been limited by the availability of suitable data, the shortcomings of existing formulae when applied to different inlets, and the difficulties particular to multi-inlet situations. Our appraisal of methodologies for studying inlet dynamics leads us to formulate a new approach for investigating inlet evolution and stability based on combining sediment budget computations (using best estimates and uncertainty analysis) and inlet hydraulic parameter analysis.The approach developed is applied to a stabilised inlet, located within a multi-inlet system (Faro-Olhão Inlet, Ria Formosa, Southern Portugal), which was opened starting 1929 and has since been dredged periodically to maintain navigability. A series of digital maps was produced based on multi-year data acquired from charts, surveys, and aerial photos. The maps were used to compute sediment volumes for six coastal cells delineated on the basis of the morphological features of the inlet. Cell volumes and fluxes were calculated for three periods (1929–1962, 1962–1978, and 1978–2001), and overall sediment budgets were calculated for the latter two periods. Inlet hydraulic parameters measured included tidal prism, inlet channel cross-sectional area and hydraulic radius, and maximum depth of the inlet throat, and were tracked over 9 bathymetric surveys from 1947–2004. The computed budget reveals that the inlet is only at present reaching volumetric equilibrium. However, the analysis of channel cross-sectional area and radius indicates parameter stability around 1978–1985, 20–25 years before the inlet started to reach volumetric equilibrium. It is hypothesised that the observed stability in parameters for the inlet post-1978 is related to the presence of fixed jetties and to a stratigraphic control that prevents further deepening, and not to the achievement of a dynamic equilibrium.The findings indicate that the coupling of sediment budget computation and inlet parameter analysis is useful for understanding historical sediment pathways and magnitudes, and for analysing the evolution of an inlet towards equilibrium. Although the analysis of inlet parameter evolution is valuable for examining the locational/geometrical stability of an inlet, it needs to be used in conjunction with sediment budget computations in order to properly infer inlet equilibrium. Moreover, existing formulae used to infer inlet stability, which relate cross-sectional area to tidal prism, should be reviewed with a view to including other external variables (e.g., stratigraphic controls) and to making their application more flexible to cope with the range of different inlet conditions. For multi-inlet systems, the coupling of morphology and hydrodynamics analysis should be extended to all inlets in order to infer the stability of the overall system based on the distribution of the tidal prism through time and the patterns of inlet circulation and sediment transport.     

洋浦港平面布置方案的数值研究比选

分析了洋浦港工程的建设将有可能引起洋浦港区的潮流、泥沙运动变化,而导致部分海岸线水域的泥沙淤积,采用了COHERENS-SED模型进行区域水流模拟,从纳潮量、流向与航道的夹角方面,对不同布置方案进行比较,比选出最佳工程布置方案。     

潮汐河口断面悬沙通量组分模式及其在长江口的应用

断面泥沙通量估算的误差主要来源于计算方法、测点布局等,通量模式应该建立在通量估算统计误差最小的原则基础之上.在断面网格设计中采用统计误差最小的等面积单元网格,在泥沙通量估算中采用泥沙组分浓度,在流速变量插值上垂向采用对数函数插值,横向采用第一边界三次方样条函数插值.这样建立的潮汐河口悬沙断面通量组分模式较以往的任何模式更完善,断面通量估算的误差最小.将该模式应用于长江河口南港断面悬沙通量估算及其输移机制分析,断面泥沙通量表现为大潮期大进大出、大出大于大进;小潮期小进小出、小出大于小进;主要输移机制是拉格朗日输移和潮泵.     

Net Sand Transport Direction in a Tidal Inlet, using Foraminiferal Tests as Natural Tracers

The relationship between the flux of exotic benthic foraminiferal tests (i.e. tests which are supplied from open-sea sources alone) in a tidal inlet and that of bulk sediment was analysed, which can be expressed as two first-order linear equations. According to this relationship, in order to determine net sediment transport directions in the entrance, the test concentration in surficial sediments of the tidal basin can be compared against a ‘ critical level ’. The critical level is determined for the conditions that no net transport of bulk sediment is present within the entrance. If the observed concentration (averaged over the tidal basin) is higher than the simulated critical level, then the net sediment transport is directed to landward. This method is applied to the analysis of net sand transport at Christchurch Harbour, a tidal inlet system located in southern England. In this investigation, concentrations of exotic foraminiferal tests in the surficial sediments of the tidal basin and ebb tidal delta area were obtained from the analysis of sea-bed sediment samples. A series of probable critical levels were calculated based upon the data sets with regard to: (1) sediment discharge from the rivers; (2) magnitude of sediment discharge within the entrance during the ebb; (3) the test concentration outside the harbour; (4) the thickness of the moving layer; and (5) two parameters associated with dispersive processes. The results show that the concentration in the tidal basin sediment is higher than a number of simulated critical concentrations for representative cases. Consequently, the high level of the concentration of exotic benthic foraminiferal tests within the harbour should be explained as a result of landward net transport of sands within the entrance.     

Sediment and hydrodynamics of the Tauranga entrance to Tauranga harbour

To relate the textural characteristics of the bottom sediments of a tidal inlet to hydrodynamics, 45 sediment samples from the Tauranga Entrance to Tauranga Harbour were analysed for textural parameters, and tidal currents and waves were monitored. Tidal currents dominate sediment transport processes near the Tauranga Entrance although swell waves are significant on the ebb tidal delta, and wind waves may influence intertidal sediments within the harbour. The bulk of the sediment is probably derived from marine sand from the Bay of Plenty continental shelf, but tidal currents and waves have changed its textural character. In areas of swift tidal currents, particularly in the inlet channel itself, sediment is coarser, more poorly sorted, and more coarsely skewed than that in areas of slower currents.     

An aggregate model for the adaptation of the morphology and sand bypassing after basin reduction of the Frisian Inlet

To study the adaptation of the morphology of the Frisian Inlet after basin reduction an aggregate model is developed. In the model, especial attention is given to the sand transport to the down-drift coast. In developing the model the inlet system is divided into three elements, the ebb tidal delta, the Zoutkamperlaag and the tidal flats. Based on observations during the first 18 years after basin reduction the adaptation time scale of the tidal flats is expected to be much larger than that of the ebb tidal delta and the Zoutkamperlaag, essentially reducing the inlet schematization to a two-element system. The dependent variables in the model are the sand volume of the ebb tidal delta and the water volume of the channel. The governing equations are non-linear and for quantitative accurate results are solved numerically. To demonstrate the nature of the solution the equations are linearized assuming the morphological state is close to equilibrium. The linearized equations are solved analytically and the solution is applied to a hypothetical case where the tidal prism of the Frisian Inlet is reduced by 10%. From the analytical solution it follows that the adaptation of the volumes of the two elements, delta and channel, is governed by two system time scales. These system time scales are functions of two local time scales. The local time scales pertain to the adaptation of one element assuming the other element has reached equilibrium. Because there are two system scales the adaptation of the volumes of the delta and channel is not exponential and is not necessarily monotonic. For example, initially the transport of sand to the down-drift coast is larger than the long-shore sand transport entering the inlet system from the up-drift coast, then becomes smaller and after some time increases again to reach the value of the up-drift long-shore sand transport. Comparison of the numerical solution for the actual reduction in tidal prism of 30% with the analytical solution for the 10% reduction in tidal prism shows qualitatively the same results.     

Process-based modeling of morphodynamics of a tidal inlet system

The morphodynamic evolution of an idealized inlet system is investigated using a 2-D depthaveraged process-based model,incorporating the hydrodynamic equations,Englund-Hansen’s sediment transport formula and the mass conservation equation.The model has a fixed geometry,impermeable boundaries and uniform sediment grain size,and driven by shore-parallel tidal elevations.The results show that the model reproduces major elements of the inlet system,i.e.,flood and ebb tidal deltas,inlet channel.Equilibrium is reached after several years when the residual transport gradually decreases and eventually diminishes.At equilibrium,the flow field characteristics and morphological patterns agree with the schematized models proposed by O’Brien (1969) and Hayes (1980).The modeled minimum cross-sectional entrance area of the tidal inlet system is comparable with that calculated with the statistical P-A relationship for tidal inlets along the East China Sea coast.The morphological evolution of the inlet system is controlled by a negative feedback between hydrodynamics,sediment transport and bathymetric changes.The evolution rates decrease exponentially with time,i.e.,the system develops rapidly at an early stage while it slows down at later stages.Temporal changes in hydrodynamics occur in the system;for example,the flood velocity decreases while its duration increases,which weakens the flood domination patterns.The formation of the multi-channel system in the tidal basin can be divided into two stages;at the first stage the flood delta is formed and the water depth is reduced,and at the second stage the flood is dissected by a number of tidal channels in which the water depth increases in response to tidal scour.     

Morphodynamics of the barrier-inlet system, west-central Florida

The barrier-inlet system along the Gulf Coast of peninsular Florida has one of the most diverse morphologies of any barrier system in the world. The delicate balance between tidal- and wave-generated processes on this low-energy coast permits only slight changes in either of these processes to result in significant and rapidly developing morphologic responses. Some of these responses are the result of natural phenomena such as hurricanes opening tidal inlets, closure of inlets due to longshore transport of sediment, and changes in the availability of sediment. Tidal prism is the primary factor in controlling inlet morphology and is greatly influenced by anthropogenic activities in the backbarrier area. Human activity has also modified the coast in many ways over the past several decades, beginning with the construction of the first causeways in the 1920s. The various modifications by development have resulted in important morphodynamic changes in the barrier-inlet system. These include hardening the coast on the beach and at inlets, dredging and filling in backbarrier environments, and construction of fill-type causeways connecting the islands to the mainland. Construction of seawalls and jetties has inhibited normal coastal processes. Examples include the downdrift erosion at Blind Pass and Big Sarasota Pass. Construction of fill-type causeways between the barriers and the mainland has created artificial tidal divides that reduce the tidal prism at some inlets, thereby resulting in instability or closure such as Blind Pass and Dunedin Pass. This is further exacerbated by dredge and fill construction that reduces tidal prism by reducing the area of open water in the backbarrier. Dredging of the Intracoastal Waterway also results in a negative impact on selected inlets by channeling tidal flux away from some inlets. Impacts of these changes inhibit the barrier/inlet environments from responding to open coast processes.     

基于解析解的长江口南港悬沙侧向捕集特征分析

为探讨长江口南港的水动力结构及悬沙侧向输运特征,本文从解析解的角度构建了潮汐河口水沙输运数学模型,并将其应用到长江口南港某横断面上。南港水动力主控于半日潮流,余流主要由陆相径流及本地非线性对流项驱动,悬沙分布上北侧副槽远大于南侧主槽,水沙分布的计算结果与实测结果在结构上基本一致。通过输沙函数进一步分析表明,潮流输沙和余流输沙是南港侧向输沙函数的两个主要部分。南港中强劲径流削弱了涨潮流,增强了落潮流,使得向河槽南侧的涨潮流输沙小于向河槽北侧的落潮流输沙,潮流输沙指向河槽北侧。径流驱动的南港侧向余流在涨潮流方向上为一逆时针环流结构,余流输沙指向河槽北侧。扩散输沙指向南侧主槽,因其总是指向悬沙浓度梯度的负方向。在各输沙因子的综合作用下,南港中大量悬沙捕集于河槽北侧,使得河槽北部底层潮平均含沙量值达到最大值。