山东半岛北岸现代海滩层理及动态解释     

曹立华  栾天  庄振业  李兵  董威力  孙羽涵 《海洋地质前沿》2011,(9):1-5,31

海滩层理由冲、回流塑造的向海倾前滨楔状交错层理和冲越流形成的向陆倾后滨斜层理组成,二者构成假背斜构造.近年在烟台—莱州岸段海滩上开挖了10个垂岸探槽,揭示出这里海滩以向陆倾后滨层理为主,并且被暴风浪侵蚀面所斜切,该面向海的前滨层理只留下几十厘米的薄层,说明近几十年海岸持续遭受侵蚀,海滩的前滨层理被多次暴风浪切割掉;按暴...  相似文献   

海岸沙坝剖面和滩肩剖面特征研究     

张洋  邹志利  苟大荀  罗年鹏  尹晶 《海洋学报》2015,37(1):147-157

通过物理模型实验研究了海岸沙坝剖面和滩肩剖面的形成和演化过程,给出了稳定的沙坝剖面和滩肩剖面的几何特征。实验中考虑了两种初始坡度(1∶20和1∶10)和不同波高的规则波和不规则波,讨论了不同初始坡度海岸上破碎波空间分布特征。结果表明,沙坝产生后存在向岸和离岸两种运动形态,但最终将停留在稳定位置。稳定的沙坝剖面对应不同初始坡度和波浪存在不同的大沙坝和小沙坝分布。沙坝剖面由长时间小波高波浪序列作用后可转化为稳定滩肩剖面,该剖面不依赖于波浪和初始坡度。实验也给出了平衡剖面与理论曲线的对比以及剖面上泥沙粒径的分布。  相似文献   

深圳大鹏半岛南岸西冲海滩的沉积物来源、平面形态稳定性及横向变化   总被引：1，自引：0，他引：1  

ZHANG Song  WANG Wei  HUANG Rihui  XU Liubing 《海洋学报(英文版)》2015,34(3):76-89

The coast of the Dapeng Peninsula has been honored as one of "the eight most beautiful coasts in China". The most precious tourism resource for the peninsula is headland bay beaches, among which the beach at Xichong on the southern coast of the peninsula is the longest and the most important one. The information of the stability, sedimentary source and shape change of the beach is very important for maintaining the beach in terms of sustainable development of the peninsula. Heavy minerals in the sand of the beach and the inland stream at Xichong are compared with those of a nearby beach on the same coast to determine the beach sand source; with help of a computer software, MEPBAY, the equilibrium planforms of the beaches on the peninsula are compared with those of an island without rivers to evaluate the stream’s effects on the beach stability; cross shore profiles along the Xichong beach are also surveyed in different seasons of a year to assess the annual shore normal beach changes affected by the stream input, and the relation between the equilibrium planform state and cross shore changes of the beach. It is shown that(1) stream is the main sedimentary source of the beach and the weathering materials of the rocky headlands on both sides of the bay transported by waves are the second source for the beach but it is limited, sand from an inner shelf is not the sedimentary source for the beach at present and was not even during the Holocene transgression;(2) the Xichong beach cannot reach static equilibrium around the entire bay shoreline, the segment of the shoreline where a stream outlet is located is in dynamic equilibrium, and the unstable section occurs in the wave shadow region in the lee of an offshore island;(3) no matter whether the section of the beach shoreline at Xichong is in an equilibrium state or not, it is eroded in the typhoon season and recovered after the season, the maximum change in erosion and accretion occurs in the unstable segment;(4) the Xichong beach can only have small sand body since it is supplied with sand mainly form inland streams, resulting in a possible danger in which sand loss induced by human activities or huge storms cannot be replenished naturally.  相似文献   

基于地形动力学的华南海滩裂流风险研究   总被引：2，自引：0，他引：2       下载免费PDF全文

李志强 《热带海洋学报》2015,34(1):8-14

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砂质海滩地形动力分类研究进展     

于吉涛  陈子燊 《热带地理》2011,31(1):107-112

海滩状态是一个地形与水动力相互作用的三维地形动力问题.国外对海滩状态的地形动力分类已开展了大量卓有成效的研究工作,既包括波控、小潮、开阔海岸海滩状态的研究,也包括波控、不同潮差海岸海滩类型的研究和岬间海岸海滩类型的研究.文中回顾并概括了自20世纪70年代至今国外在砂质海滩地形动力分类方面代表性的研究工作,这些对于我国的...  相似文献   

Evolution and Morphodynamics of a Prograded Beach‐Ridge Foreland,Northern Baffin Island,Canadian Arctic Archipelago          下载免费PDF全文

Dominique St‐Hilaire‐Gravel  Donald L. Forbes  Trevor Bell 《Geografiska Annaler: Series A, Physical Geography》2015,97(3):615-631

Landward retreat (marine transgression) is a common response of coastal systems to rising relative sea level. However, given sufficient sediment supply, the coast may advance seaward. The latter response of gravel barriers has been recorded in parts of southeastern and northwestern Canada, where seaward‐rising sets of beach ridges are observed in areas of Holocene RSL rise. Cape Charles Yorke, northern Baffin Island, is a 5 km long gravel foreland characterized by seaward‐rising beach‐ridge crest elevations. The prograded morphology of the Cape Charles Yorke foreland is a prime example of coastal response to a combination of rising RSL and abundant sediment supply, an unusual and little‐documented pattern in the Canadian Arctic. The main gravel supply to Cape Charles Yorke is likely from eroding bedrock and raised marine deposits southwest of the foreland. Although not the dominant sediment source, the Cape Charles Yorke delta contributed to the formation of the foreland by sheltering it from easterly storm waves and providing an anchor point for the prograding ridges. The truncation of relict ridges by the modern shoreline suggests a recent regime shift from continuous deposition to predominant erosion. The cause and timing of this shift are unknown but could result from a recent dwindling in sediment supply, increased accommodation space, increased wave energy, and/or an accelerated rise of relative sea level.  相似文献   

Physical determinants of intertidal communities on dissipative beaches: Implications of sea-level rise     

Tsuyuko Yamanaka  Dave RaffaelliPiran C.L. White 《Estuarine, Coastal and Shelf Science》2010

Sea-level rise is likely to cause significant changes in the morphodynamic state of beaches in the higher latitudes, resulting in steeper beaches with larger particle sizes. These physical changes have implications for beach invertebrate communities, which are determined largely by sediment particle size, and hence for ecosystem function. Previous studies have explored the relationships between invertebrate communities and environmental variables such as particle size, beach slope and exposure to wave action, and often these physical variables can be integrated in various indices of morphodynamic state. Most of these studies incorporated a full range of beach types that included wave-dominated surf beaches, where the wave action is harsh enough to enable reliable estimates of breaker height, a parameter included in several of the indices, and concluded that more dissipative beaches with gentler slopes and finer particle sizes often support a higher number of species and greater abundance than more reflective beaches. Whether these predictions remain valid for less wave-dominated beaches, where breaker height is more difficult to determine, is uncertain. In the present study, the abundance of meio- and macrofauna was quantified across a range of beaches in the UK, which are generally towards the lower energy end of the morphodynamic gradient, and their relationships with beach physical properties explored. No significant relationships were found between abundance and the standard morphodynamic indices, but significant relationships were found for both macro- and meiofaunal abundance when these indices were combined with an exposure index (derived from velocity, direction, duration and the effective fetch). All the relationships identified between abundance and combined morphodynamic indices indicated a higher abundance of both macro- and meiofauna on the more dissipative beaches. The reverse was however found for species richness. If predictions that accelerated sea-level rise will move beaches towards a more reflective morphodynamic state are correct, this could lead to declines in the abundance of meio- and macrofauna, with potential adverse consequences for ecosystem functioning.  相似文献   

Uncertainty in the application of the parabolic bay shape equation: Part 2     

Robert Lausman  Antonio H.F. Klein  Marcel J.F. Stive 《Coastal Engineering》2010

This paper attempts to highlight issues that are relevant in the application of the Parabolic Bay Shape Equation (PBSE) to a non-equilibrium bay. For this case, the bay of Imbituba in southern Brazil was chosen. The construction of a breakwater to shelter the port of Imbituba in the south of the bay was accompanied by an increase in sedimentation to the port area from an eroding downdrift beach. Superimposed plots of the coastline of the Bay of Imbituba from different years confirm a general trend of accretion of the southern part of the bay accompanied with a retreat of the coastline in the northern part. After the application of the PBSE it became clear that the breakwater caused a change in the equilibrium state of the bay. Between 1947 and 2001 the Bay of Imbituba has changed from a dynamic equilibrium to a natural beach reshaping or self-reshaping. The tendency of the sedimentation of the southern part of the bay can be explained by the SEP associated with the new updrift diffraction point (tip of the breakwater): The seaward position of the SEP predicts a need for additional sediment in order to achieve a stable plan form.  相似文献   

Static bay beach concept for scientists and engineers: A review     

John R.-C. Hsu  M.-J. Yu  F.-C. Lee  Lindino Benedet 《Coastal Engineering》2010

Headland-bay beach (HBB) is one of the most prominent physiographic features on the oceanic margin of many countries in the world. Under the influence of a predominant swell, its curved periphery in natural environment may reach static equilibrium and remains stable without sediment supply from updrift and/or a riverain source within its own embayment. Coastal scientists and engineers have attempted to develop mathematical expressions to quantify this ideal bay shape since the 1940s. As the scenario with depleting sediment supply has become a common reality on many parts of the world coastline in more recent time, some coastal engineers have advocated a rational approach to mimicking the static bay shape found in nature in order to mitigate beach erosion as well as for coastal management. Nowadays, many useful applications have emerged since the publication of the parabolic bay shape equation (PBSE) developed for static equilibrium planform (SEP) in late 1980s. The advance in modern computer technologies and international collaboration has further facilitated the exchange of knowledge and applications of this static bay beach concept (SBBC).  相似文献   

Lessons from a Disturbance Experiment in the Intertidal Zone of an Exposed Sandy Beach     

D. S. Schoeman  A. Mclachlan  J. E. Dugan 《Estuarine, Coastal and Shelf Science》2000,50(6):869

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