福建沿岸海滩—沙丘系统地貌变化特征及关系模式

通过2007年7月至2010年2月对福建沿岸25个主要沙丘岸段的调查,以及代表性海滩-沙丘地貌系统地形变化的重复观测,针对福建海岸海滩类型和前缘沙丘地貌组合,从海滩动力地貌特征、沙丘形态及其变化角度出发,分析了海滩-沙丘地貌体系的变化特征,并进一步探索海滩动力地貌与沙丘地貌及其变化之间的关系模式。结果为:(1)福建沿岸海滩-沙丘系统的地貌变化可以归纳为3种类型:①海滩稳定-沙丘变化型;②海滩侵蚀-沙丘稳定型;③海滩侵蚀-沙丘后退型。(2)福建沿岸海滩-沙丘系统的动力地貌关系可以归纳为6种基本模式,主要表现为完全耗散型、过渡型和低潮阶地型3种海滩地貌与沙丘规模和形态的对应关系,海滩的沉积状态与海滩-沙丘系统内部的相互作用,也在某种程度上决定了其动力地貌关系模式。     

基于GPR图像的福建长乐海岸沙丘沉积构造与海岸环境演变

为了探讨福建长乐东部海岸环境演变,运用探地雷达(GPR)探测了研究区海岸沙丘的沉积构造,初步得出以下结论:(1)研究区海岸沙丘沉积构造主要由海滩沉积和海岸沙丘沉积构成,其中下伏沉积为海滩波浪作用形成的波状交错层理,上覆沉积为风成大角度倾斜的交错层理以及局部的水平层理;(2)上部发育的倾向向背的大角度风成交错层理,反映了研究区丰富的沙源、宽阔的海滩、植被扩张的进积海岸特点;(3)从沉积序列分析,研究区海岸地貌环境演变经历了早期的滨岸浅海到晚期的海岸沙丘带两个阶段,反映了海岸向东的进积过程中,外力作用由波浪作用为主演变为风沙沉积作用为主。     

海岸沙丘风暴侵蚀研究现状与展望

基于对海岸沙丘风暴侵蚀研究的简要回顾,概括了我国海岸沙丘风暴侵蚀概况,以及国外近期在海岸沙丘侵蚀机理、海岸沙丘风暴响应过程等方面的主要研究进展,提出了存在的科学问题。针对我国海岸风暴侵蚀研究的不足之处,应及时开展海岸沙丘资源现状调查与评估、典型岸段的风暴侵蚀机理拓展研究,以及海岸沙丘功能维持和生态养护技术示范和应用等,探究海岸沙丘风暴侵蚀机理,建立一套海岸沙丘风暴侵蚀评估和管理技术。     

海滩养护影响下的海岸风沙作用研究进展

海滩养护已经成为全球基于自然(nature-based)海岸防护的主要手段,并得到广泛应用。随着全球强风区海岸海滩养护工程数量的增加,海滩养护对海岸风沙过程产生的一系列影响逐渐得到重视。海滩养护工程形成了新的海滩地貌形态,扩大了海滩风区、增加了风沙物源、提高了滩面高程、改变了滩面沉积物,海滩地貌和沉积物组分变化引起了风沙运动过程的变化,与自然海滩风沙过程相比,有其独特的过程和特征,已经成为海岸风沙研究的热点之一。本文从海滩养护影响下的风沙环境变化、风沙活动变化以及养护海滩对沙丘的影响等3个方面梳理了国内外研究进展,提出养护海滩风沙研究存在区域不平衡以及风沙过程的综合性影响和定量化研究不足等问题,并结合我国海滩养护未来的发展趋势,从强风区养护海滩风沙运动规律、养护海滩风沙环境全要素的综合影响和风沙作用变化的模型评估等方面展望了我国养护海滩风沙研究的未来发展方向。     

近2000年来福建南部海岸沙丘记录的风沙活动序列

对福建南部漳浦地区赤湖海岸沙丘(CH)和大澳海岸沙丘(CDS)近2 000年以来海岸风沙活动历史及其东亚冬季风(EAWM)的关系进行研究。在野外沙丘剖面沉积构造考察基础上, 通过光释光(OSL)测年技术重建研究区海岸风沙活动序列。结果表明: (1)漳浦海岸有近2 000年来发育的多期海岸风沙沉积, 其中, CH沙丘记录的风沙活动期分别为BC100–AD300年、AD500–AD870年、AD1050–AD1380年; CDS沙丘记录了AD200年左右、AD1040–AD1280年以及AD1410–AD1710年3个风沙活动期。(2)研究区海岸风沙活动期与我国东部海岸、东北亚及西北欧海岸风沙活动期大体一致。可能反映了近2 000年以来北半球气候环境发生了大范围的阶段性变化, 各个区域海岸风沙活动起止时间的不同, 反映了各地所处大气环流系统位置的分异或是地方性因素的差异。(3)东亚冬季风对福建南部沿海的风沙活动有明显影响。一般来讲, EAWM强盛时, 海岸风沙沉积比较活跃。虽然在最近2000年的冷暖期都有海岸风沙沉积, 但在暖期仅限于EAWM相对强盛的时期。EAWM影响范围广阔, 是东亚海岸风沙活动周期具有准同时性的基本驱动因素。此外, 北大西洋涛动(NAO)通过影响EAWM的强度驱动海岸风沙活动的阶段性发生, 因而对研究区海岸沙丘发育产生间接影响。本文讨论近2 000年以来季风区海岸沙丘演变序列及驱动机制, 可提取百年尺度上的海岸沉积古环境信息, 探讨东亚冬季风演化特征。     

粤东靖海湾海岸地貌动力演变及其工程影响

受人为工程的影响,相对稳定的岬湾海岸地貌常经历显著的动态调整。本文以粤东靖海湾典型岬湾海岸为例,运用Mc Laren模型、波浪动力场数值模拟、等深线对比、冲淤计算等多种方法,从海岸地貌动力学角度,对人为岬角工程前后岬湾海岸地貌动力过程和冲淤演变进行综合分析。结果表明:1)海岸地貌动力系统内常存在负反馈机制以维持系统的稳定。岬角工程后上岬角防波堤沿SSW延伸,ESE和E向浪经过防波堤时发生绕射,波能削减,湾顶动力减弱,海滩沉积物从下岬角向湾顶反向运移;2)海滩的蚀积状态在工程前后发生了转换,工程前遮蔽段侵蚀、开敞段堆积;工程后遮蔽段堆积、开敞段侵蚀;3)海湾水下地形对岬角工程的响应敏感,工程后海湾水下地形冲淤剧烈。     

华南弧形海岸的分形和稳定性研究

弧形海岸是上、下岬角控制下的砂质海岸在泥沙供给不足的情况下优势波浪斜向冲击海岸形成的一种与波浪动力及其一定的沿岸输沙率相适应的海岸形态.它的弧形(或螺线形)湾顶偏于上岬角一侧,其海滩剖面平缓,呈上凹形,属“消散型”海滩性质;偏于下波侧方向的岸段(称切线段)十分平直,其海滩剖面较陡,呈上凸状,趋于“反射型”海滩性质.这是一种较为稳定或平衡的、在华南分布很广的海岸类型.     

秦皇岛市海岸风成沙丘的研究

秦皇岛市北戴河向南直至滦河河口发育着我国最长的沙丘海岸，沙丘高约20～30m，最高42m。在沙丘发育最充分的地区自岸向陆，沙丘按形态可分成岸前沙丘，沿岸主沙丘链，斜向沙丘链和平坦沙席等4种类型。沙丘由分选极好的中细砂组成，具有微弱的负偏态和双跃移特征。沙丘内部发育有高角度板状交错层理、低角度楔状交错层理等层理构造。滦河新三角洲和沿岸海滩的丰富沙源、向岸和离岸两盛行风的频繁交替以及适宜的空旷地形空间是塑造沙丘的主要条件。加强管理，保护沙丘的自然面貌是当务之急。     

黄、渤海海岸风沙地貌类型及其分布规律和发育模式

于１９９０－１９９４年，对黄，渤海海岸风沙地貌，风沙沉积，风沙灾害和土地沙漠化现象进行详细的外业调查，测量和填图，在此基础上，利用ＧＩＳ技术原理，对海岸岗沙地貌进行系统的分类研究，对海岸风沙地貌分布规律和发育模式进行较深入的探讨，结果表明，研究区风沙地貌，风沙灾害和土地沙漠化现象主要分布在冬，春季气候干旱，风力强而持久，砂源丰富的渤海海岸和山东半岛半岸的砂质海岸地区，海岸沙丘和风成砂地总面积达７０     

福建长乐东部海岸沙丘风蚀坑研究

沙丘风蚀坑是沙质海岸常见的风成地貌形态,是固定沙丘开始活化的明显标志.福建长乐东海岸风沙规模大、地貌类型多样,发育了许多典型的海岸沙丘地貌.由于各种自然和人为因素的作用,部分海岸沙丘发育了风蚀坑.根据对研究区风蚀坑的实地调查,本文论述了风蚀坑的形态特征、风蚀坑内的风速与风向变化,以及风蚀坑的风沙搬运与沉积过程,并对风蚀坑的成因和风蚀坑的演化阶段进行了讨论.文中得出以下几点结论:(1)研究区主要发育槽形风蚀坑,风蚀坑中轴线的方位多介于NE40°～NE65°之间,两侧侵蚀壁坡度介于35°～40°之间.(2)大型风蚀坑,风速在顶部最大.小型风蚀坑,较狭窄部位的风速可能大于项部.(3)大型风蚀坑,沿着中轴线上风向基本上保持不变,近侵蚀壁的风向则发生不同程度的改变.小型风蚀坑,从坑口到坑顶的风向变化明显.     

国外海岸沙丘形成与演化的研究

自20世纪80年代以来，国外对海岸沙丘的研究已从主要对其地貌形态的研究转向海岸海丘与海岸变迁尤其是全球变化关系的研究上，海岸沙丘形成与演化的研究倍受关注，进行了大量研究并取得了一定的研究成果。这里介绍了国外在海岸沙丘形成与演化研究方面的主要进展及其成果，并以此探讨了国内今后开展海岸沙丘形成与演化研究的主要方向与问题。     

Sediment facies and pathways of sand transport about a large deep water headland,Cape Rodney,New Zealand

Cape Rodney is a large headland that protrudes 3–4 km into deep water in the Hauraki Gulf and separates the Mangawhai‐Pakiri and Omaha littoral cells. Detailed swath mapping of seabed sediments around Cape Rodney was carried out using by side‐scan sonar and ground‐truthed by SCUBA, grab sampling, and video. Despite the barrier imposed by the headland two pathways of sand transport around the headland, separated by the topographic high of Leigh Reef, have been identified. One lies close to the headland, where sand from the beach and nearshore of the Mangawhai‐Pakiri embayment is driven by waves and currents along a 500‐m‐wide pathway in c. 20–25 m depth around the headland to the vicinity of Leigh Harbour. The other lies in 50 m water‐depth seawards of Leigh Reef. Here fine sand, sourced from the nearshore of the Mangawhai‐Pakiri embayment and driven offshore from the tip of the headland, is transported back and forth by tidal currents in 50 m water depth on the floor of the Jellicoe Channel. The sand bodies along both these pathways are thin and so sand leakage from the Mangawhai‐Pakiri embayment is thought to be small. Transport at these depths is dependent on both tide and wave generated currents and episodic occurring during storm events. The sediment facies associated with little sand transport about a headland in deep water is one of thin and discontinuous and patchy sand cover between rocky areas and over coarser megarippled substrate. Ocean swell, tidally driven phase eddies that spin up on both sides of the headland, and bathymetry all play a role in shaping those facies.     

Management of Mediterranean coastal dunes

This paper gives some theoretical concepts of dune management as well as practical examples of how actual measures should be carried out.Dune management is defined as all measures aimed at the preservation and restoration of the natural values of a coastal sand dune area. It is essential that beach and foreshore are seen as parts of a whole dune system. Management must take into account all processes within this system. It should aim at nature conservation and wise use of coastal resources and all forms of land use should be ecologically sustainable. Dune management should work as much as possible ‘with’ the natural processes and not ‘against’ them.Four types of Mediterranean dune systems (including Portugal and SW Spain) are distinguished:: mainland dunes, lagoon-bay barrier dunes, delta dunes and remnant dunes.Like in most parts of the world, Mediterranean dunes fulfill several functions at the same time. The following functions will be dealt with: nature management, coastal defence and erosion, dune stabilisation and afforestation, agriculture, tourism and urbanisation, recreation, golf, information and education. The concepts of management which are considered include: sustainable use, large and coherent units, compensation, management planning, environmental impact assessment and function analysis.Dune stabilisation is not always considered necessary. In case of stabilisation by planting, only indigenous species should be used, preferably pioneers and not trees. Planting of exotic species should be avoided.     

海岸新月形沙丘的表面粒度分异——以河北昌黎黄金海岸为例

河北昌黎黄金海岸是我国海岸沙丘的集中分布区,选择其中形态典型的新月形沙丘,分不同部位采集了42个沙丘表面沉积物粒度样品,通过对采集样品粒度及其参数的分析与计算,研究了其表面粒度分异。结果表明,昌黎黄金海岸新月形沙丘两翼、迎风坡脚、迎风坡、沙丘顶部、背风坡、背风坡脚的粒度总体上是中砂、分选好、偏度近对称和中等峰态,只有平均粒径在新月形沙丘表面的不同部位存在一定的差异,自迎风坡脚到沙丘顶部粒径变粗,背风坡粒径相对变细,到背风坡脚粒径又变粗,整个沙丘表面粒径顶部最粗、背风坡最细,其分布可以归入沙丘顶部砂物质最粗的分布模式。该粒度分布模式是本区域主风向与强风向交替变化及其风力差异、沙丘两侧不对称和凹型迎风坡形态等组合作用的结果。     

Morphological characteristics and sand volumes of different coastal dune types in Essaouira Province, Atlantic Morocco

Altogether three coastal dune fields, one located north and two south of the city of Essaouira, Atlantic Morocco, have been investigated to establish the distribution and overall sand volumes of various dune types. The purpose of the study was to characterize and classify the aeolian landforms of the coastal dune belt, to estimate their sand volumes and to assess the effectiveness of coastal dune stabilization measures. The northern dune field is 9 km long and lined by a wide artificial foredune complex fixed by vegetation, fences and branches forming a rectangular grid. Active and ephemeral aklé dunes border the inner backshore, while some intrusive dunes have crossed the foredune belt and are migrating farther inland. The total sand volume of the northern dune belt amounts 13,910,255 m³. The central coastal sector comprises a much smaller dune field located just south of the city. It is only 1.2 km long and, with the exception of intrusive dunes, shows all other dune types. The overall sand volume of the central dune field amounts to about 172,463 m³. The southern dune field is characterized by a narrower foredune belt and overall lower dunes that, in addition, become progressively smaller towards the south. In this sector, embryonic dunes (coppice, shadow dunes), tongue-like and tabular dunes, and sand sheets intrude from the beach, the profile of which has a stepped appearance controlled by irregular outcrops of old aeolianite and beach rock. The total volume of the southern dune field amounts 1,446,389 m³. For the whole study area, i.e. for all three dune fields combined, a sand volume of about 15,529,389 m³ has been estimated. The sand of the dune fields is derived from coastal erosion and especially the Tensift River, which enters the sea at Souira Qedima some 70 km north of Essaouira. After entering the sea, the sand is transported southwards by littoral drift driven by the mainly north-westerly swell climate and the Trade Winds blowing from the NNE. This sand feeds the beaches along the coast, from where it is blown obliquely onshore to generate the dune fields. The maximum sand input occurs in the north, from where it gradually decreases southwards, this being also reflected in the grain size and dune typologies. The study shows that dune stabilization measures have been reasonably effective along most of the coast, with the exception of a large area immediately north of Essaouira where the almost complete destruction of the plant cover has reactivated sand mobility—this may in the future threaten the city.     

河北七里海外海岸沙丘群成因新探

七里海有中国第一大潟湖之称,多数学者认为七里海外的海岸沙丘群是在滨外沙坝的基础上发育形成的。研究认为,七里海外的海岸沙丘群是在末次冰期时期风成沙丘群的基础上演化形成的继承性沙丘综合体。七里海也不是科学意义上的潟湖,它没有形成海岸沙坝这一潟湖形成的过程,其前身是晚更新世末期由风暴活动形成的风蚀洼地。应加强七里海外海岸沙丘群的形成、发育类型及演化过程的研究,从多角度探究七里海外海岸沙丘群的演化机理和发育趋势。     

Design and performance of headland bays in Chesapeake Bay,USA

The use of headland-breakwater systems along the shore of Chesapeake Bay began in the early 1980s. Properly designed and installed headland breakwaters with beach fill and wetlands plantings provide shore protection and create a “full” coastal profile of beach/backshore/dune which enhances habitat. They create a tertiary buffer for upland runoff and groundwater and provide access and recreation. The wetland grasses also create an erosion resistant turf. The coastal profile accommodates environmental permitting requirements of habitat enhancement for shore protection structures.     

Calculation of beach change under interacting cross-shore and longshore processes

This paper presents a mathematical approach and numerical model that simulates beach and dune change in response to cross-shore processes of dune growth by wind and dune erosion by storms, and by gradients in longshore sand transport that will alter shoreline position. Sub-aerial transport processes are represented, whereas sub-aqueous transport is neglected. The system is tightly coupled morphologically, with the berm playing a central role. For example, the potential for sand to be transported to the dune by wind depends on berm width, and sand lost in erosion of the dune during storms can widen the berm. Morphologic equilibrium considerations are introduced to improve reliability of predictions and stability of the non-linear model. An analytical solution is given under simplification to illustrate properties of the model. Sensitivity tests with the numerical solution of the coupled equations demonstrate model performance, with one test exploring beach and dune response to potential increase in storm-wave height with global warming. Finally, the numerical model is applied to examine the consequences of groin shortening at Westhampton Beach, Long Island, New York, as an alternative for providing a sand supply to the down-drift beach. Results indicate that the sand will be released over several decades as the shoreline and dune move landward in adjustment to the new equilibrium condition with the shortened groins.