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1.
《Coastal Engineering》2006,53(1):65-79
Submerged coastal structures are widely perceived to be capable of providing beach protection, without the adverse impacts (including loss of beach amenity and aesthetic considerations) often associated with more conventional structures such as revetments and groynes. In addition, there is growing interest in the concept that the layout and cross-section of submerged coastal protection structures can be optimised to also enhance local surfing conditions. However, as submerged structures have only rarely been adopted for beach protection, the shoreline response to these structures is not well understood at present. Therefore, this review of the available published literature was undertaken with the aim of investigating the environmental and structural parameters governing shoreline response to submerged structures, gleaned from the results of field, laboratory and numerical studies undertaken to date.The review reveals that, contrary to expectations, a majority of the submerged structures constructed to date have resulted in shoreline erosion in their lee. Furthermore, the key environmental and structural parameters governing the mode (i.e. erosion or accretion) and the magnitude (i.e. size of salient) of shoreline response to submerged structures are yet to be identified. Although submerged coastal structures offer the potential for low aesthetic impact incorporating multi-function design, until the response of the adjacent shoreline to submerged structures is better resolved, their use is likely to remain relatively limited. 相似文献
2.
Spatial Modeling and Analysis for Shoreline Change Detection and Coastal Erosion Monitoring 总被引：3，自引：0，他引：3
Coastal erosion presents a serious problem throughout U.S. coastal areas. The Ohio Geological Survey estimates that more than 3,200 acres of Ohio's Lake Erie shore have been lost to erosion since the 1870s, resulting in economic losses exceeding tens of millions of dollars per year. This article presents research results of a project that monitors shoreline erosion using high-resolution imagery and examines erosion causes. Spatial modeling and analysis methods are applied to the project area along the south shore of Lake Erie. The shoreline is represented as a dynamically-segmented linear model that is linked to a large amount of data describing shoreline changes. A new method computes an instantaneous shoreline using a digital water level model, a coastal terrain model, and bathymetric data. This method provides an algorithm for deriving the Mean-Lower Low Water (MLLW) and the Mean High Water (MHW) shorelines that are essential to navigation charts. The results describe a part of our effort towards a coastal spatial information infrastructure to support management and decision-making in the dynamic coastal environment. 相似文献
3.
长久以来,人们采用各咎护岸工程保护遭受侵蚀的岸段,却忽视了由这些护岸建筑引起的负面效应－－干坝、突堤、离岸堤可导致邻近岸段的蚀退;海提、护岸至少经岸下蚀;海滩的人工再塑难以解决沙源,一个护岸工程,不仅要在工程上可行,还应地周边环境产生负面影响,本文就此提出了几点建议。 相似文献
4.
P. Yunus Ali 《Marine Geodesy》2013,36(1):26-39
The tsunami waves generated during the Sumatra-Andaman earthquake of 26 December 2004 devastated the coastal area along Trinkat Island, causing sudden changes to the morphology of the landforms. This study uses a series of satellite images to record the short-term morphological response and shoreline changes as well as the recovery of coastal land after its destruction. Results indicate that the island experienced substantial erosion and a significant reduction in land area. Shoreline erosion is more prevalent than accretion at an average linear regression rate of ～?9 m per year between 2004 and 2013. The major morphological changes at Trinkat Island were observed in coastal inlets, beaches, and bay head-lands. Straight beaches had almost recovered eight years after the tsunami; however, erosion is continually observed in other areas. Our study will help understanding the response and recovery of shorelines in Indian Ocean regions after the 2004 tsunami. 相似文献
5.
为加强海洋生态环境保护,强化围填海和自然岸线生态环境监管制度建设,切实解决我国围填海的突出生态环境问题,文章基于2002—2018年全国围填海和自然岸线现状,分析当前我国围填海和自然岸线生态环境监管存在的不足,并提出具有针对性的对策建议。研究结果表明:全国大陆自然岸线保有率达标形势严峻;违规审批、处罚不力和监管不到位等导致大量围填海闲置以及自然岸线受损严重等问题;法律层面的滞后是造成监管不足的因素之一,建议尽快启动《中华人民共和国海洋环境保护法》的修订工作,从强化围填海事前审查、完善围填海事中事后监管、加强自然岸线监管保护、提高围填海生态环境损害成本和强化地方监管责任5个方面完善法律制度建设。 相似文献
6.
《Coastal Engineering》2006,53(11):879-895
Shore erosion is currently causing millions of dollars worth of damage to shorelines and public properties not only along the east coast of Korea but also around the world. Little else needs to be said to emphasize that, without adequate protection, a very significant part of our coastline will fall prey to the ravages of the sea and to man himself. In recent years, because of the shortage of natural rock, traditional forms of river and coastal structures have become very expensive to build and maintain. Therefore, the materials used in hydraulic and coastal structures are changing from the traditional rubble and concrete systems to cheaper materials and systems. One of these alternatives employs geotextile tube technology in the construction of shore protection structures, such as groins, jetties, detached breakwaters and so on. Recently, geotextile tube technology has changed from being an alternative construction technique and, in fact, has advanced to become the most effective solution of choice.This paper presents the various issues related to the geotextile tube construction for shore protection at Young-Jin beach on the east coast of Korea. A new approach to a stability analysis by 2-dimensional limit equilibrium theory is highlighted and the hydraulic model test results and case history of Young-Jin beach projects are described. Based on the results of stability analysis and hydraulic model tests, a two line geotextile tube installed with zero water depth above crest was found to be more stable and effective for wave absorption than other design plans. Also, the shoreline at Young-Jin beach was extended by about 2.4–7.6 m seaward, and seabed sand was gradually accumulated around areas covered by the geotextile tube. 相似文献
7.
The shoreline is one of the most important features on earth's surface. It is valuable to a diverse user community. But the dynamic nature of the shoreline makes it difficult to be represented in a naturally dynamic style and to be utilized in applications. The officially used shoreline, for example in nautical charts, is the so-called tide-coordinated shoreline. It is also the shoreline that makes the computation of shoreline changes and associated environmental changes meaningful. Mapping of the tide-coordinated shoreline has been very costly. On the other hand, instantaneous shorelines extracted from different data sources may be available. Also, high-resolution satellite and airborne imagery have the capacity of stereo imaging and can be used to extract instantaneous shorelines at a high accuracy and low cost. This article proposes an approach to derivation of digital tidecoordinated shorelines from (a) those instantaneous shorelines and (b) digital coastal surface models and a digital water surface model. Some preliminary study results, analysis, and the potential of the approach are discussed. 相似文献
8.
Bypassing of the coastal sediment at inlets is required to prevent downdrift erosion or the filling in of navigation channels. When coastal structures such as jetties or terminal groins are placed along the inlet boundaries, bypassing is reduced but not eliminated. Bypassing solutions such as Pelnard-Considere (1956) [Pelnard-Considere, R., 1956. Essai de Theorie de l'Evolution des Forms de Rivages en Plage de Sable et de Galets, Fourth Journess de l'Hydralique, les energies de la Mer, Question III, Rapport No. 1, pp. 289–298.] are known although the effect of existing background erosion on such bypassing is not so well known. The occurrence of existing erosion due to offshore sand loss complicates the bypassing situation. The following note reviews existing analytical bypassing solutions and presents a solution and nomograms for solving a bypassed amount when existing erosion occurs along a shoreline and the sand which bypasses the updrift structure is assumed to reach the downdrift shoreline without being trapped in shoals or inlet channel. 相似文献
9.
Studies of shoreline progradation along low-energy vegetated shorelines have been limited, as these environments are generally experiencing erosion rather than deposition, with extreme erosion rates frequently found. This study examined yearly changes along a vegetated shoreline at Calaveras Point Marsh, South San Francisco Bay, California, using aerial photography, to determine the roles of climatic, watershed, and coastal process in driving shoreline changes. In addition, sediment accumulation was monitored on a yearly basis at 48 locations across the marsh to determine the role of geomorphic factors in promoting accumulation. Calaveras Point Marsh was found to have expanded from 49.26 ± 5.2 to 165.7 ± 4.7 ha between 1975 and 2005. Although the rate of marsh expansion was not positively correlated with yearly variability in precipitation, local streamflow, delta outflow, water level observations, population growth, or ENSO indices, marsh growth was greater during years of higher than average temperatures. Warmer temperatures may have promoted the recruitment and growth of Spartina foliosa, a C4 grass known to be highly responsive to temperature. Other factors, such as the formation of a coastal barrier, a recent change in the location of the mouth of the Guadalupe River, and channel readjustment in response to diking are credited with driving the bulk of the marsh expansion. Sediment accumulation was found to be high closest to channels and to the shoreline, at low elevations and in recently vegetated marsh. Globally, the pace of sea level rise exerts the primary control on wetland development and persistence. However, at local geographic scales, factors such as tectonic events, modifications to natural sediment transport pathways or land use changes may overwhelm the effects of regional sea level rise, and allow for wetlands to develop, expand and persist despite rapid sea level rise. 相似文献
10.
This paper presents a new numerical model for shoreline change which can be used to model the evolution of shorelines with large curvature. The model is based on a one-line formulation in terms of coordinates which follow the shape of the shoreline, instead of the more common approach where the two orthogonal horizontal directions are used. The volume error in the sediment continuity equation which is thereby introduced is removed through an iterative procedure. The model treats the shoreline changes by computing the sediment transport in a 2D coastal area model, and then integrating the sediment transport field across the coastal profile to obtain the longshore sediment transport variation along the shoreline. The model is used to compute the evolution of a shoreline with a 90° change in shoreline orientation; due to this drastic change in orientation a migrating shoreline spit develops in the model. The dimensions of the spits evolving in the model compare favorably to previous model results and to field observation of the Skaw Spit in the north of Denmark. 相似文献
11.
Digital Tide-Coordinated Shoreline 总被引：4，自引：0，他引：4
The shoreline is one of the most important features on earth's surface. It is valuable to a diverse user community. But the dynamic nature of the shoreline makes it difficult to be represented in a naturally dynamic style and to be utilized in applications. The officially used shoreline, for example in nautical charts, is the so-called tide-coordinated shoreline. It is also the shoreline that makes the computation of shoreline changes and associated environmental changes meaningful. Mapping of the tide-coordinated shoreline has been very costly. On the other hand, instantaneous shorelines extracted from different data sources may be available. Also, high-resolution satellite and airborne imagery have the capacity of stereo imaging and can be used to extract instantaneous shorelines at a high accuracy and low cost. This article proposes an approach to derivation of digital tidecoordinated shorelines from (a) those instantaneous shorelines and (b) digital coastal surface models and a digital water surface model. Some preliminary study results, analysis, and the potential of the approach are discussed. 相似文献
12.
James Flocks Michael D. Miner David C. Twichell Dawn L. Lavoie Jack Kindinger 《Geo-Marine Letters》2009,29(6):359-378
The barrier-island systems of the Mississippi River Delta plain are currently undergoing some of the highest rates of shoreline
retreat in North America (~20 m/year). Effective management of this coastal area requires an understanding of the processes
involved in shoreline erosion and measures that can be enacted to reduce loss. The dominant stratigraphy of the delta plain
is fluvial mud (silts and clays), delivered in suspension via a series of shallow-water delta lobes that prograded across
the shelf throughout the Holocene. Abandonment of a delta lobe through avulsion leads to rapid land subsidence through compaction
within the muddy framework. As the deltaic headland subsides below sea level, the marine environment transgresses the bays
and wetlands, reworking the available sands into transgressive barrier shorelines. This natural process is further complicated
by numerous factors: (1) global sea-level rise; (2) reduced sediment load within the Mississippi River; (3) diversion of the
sediment load away from the barrier shorelines to the deep shelf; (4) storm-induced erosion; and (5) human alteration of the
littoral process through the construction of hardened shorelines, canals, and other activities. This suite of factors has
led to the deterioration of the barrier-island systems that protect interior wetlands and human infrastructure from normal
wave activity and periodic storm impact. Interior wetland loss results in an increased tidal prism and inlet cross-sectional
areas, and expanding ebb-tidal deltas, which removes sand from the littoral processes through diversion and sequestration.
Shoreface erosion of the deltaic headlands does not provide sufficient sand to balance the loss, resulting in thinning and
dislocation of the islands. Abatement measures include replenishing lost sediment with similar material, excavated from discrete
sandy deposits within the muddy delta plain. These sand bodies were deposited by the same cyclical processes that formed the
barrier islands, and understanding these processes is necessary to characterize their location, extent, and resource potential.
In this paper we demonstrate the dominant fluvial and marine-transgressive depositional processes that occur on the inner
shelf, and identify the preservation and resource potential of fluvio-deltaic deposits for coastal management in Louisiana. 相似文献
13.
H. Lantuit V. Rachold W.H. Pollard F. Steenhuisen R. Ødegård H.-W. Hubberten 《Marine Geology》2009,257(1-4):1-10
Changing environmental conditions in the Arctic will affect patterns of coastal erosion processes and thus modify the carbon cycle in the Arctic Ocean. To address this issue, a coastal classification of the Arctic was established to provide the first reliable estimate of organic carbon input from coastal erosion to the Arctic Ocean. The calculation relies on geomorphic parameters and the length of the coastline in the form of a line dataset used in geographical information systems (the World Vector Shoreline). The statistical self-similarity of Arctic shorelines (i.e. the fact that they exhibit similar features and hence different lengths at different scales) hampers the calculation process. Delineating the same section of shoreline at different spatial scales produces changes in the calculated length of the coastline and therefore in the volume of sediment released by up to 30% in some cases. The amount of change differs depending on the type and morphology of the coastline. The length of the World Vector Shoreline does not correlate well to any one scale and is inappropriate for use at the global level. Computations of erosion based on areas instead of lengths (i.e. buffers instead of shoreline lengths) provide a valuable yet simple substitute to the length-based method. Differences in quantities of eroded sediment are, on average, 70% less affected by scale changes when areas are used. Area-based methods are therefore recommended for circum-polar, computation-demanding, shoreline-based erosion calculations. 相似文献
14.
1973 年以来射阳河口附近海岸蚀淤变化遥感分析 总被引：1，自引：0，他引：1
以射阳河口北部扁担港口和射阳河口南部斗龙港口之间的海岸作为研究区,基于1973,1987,2000和2013年四期Landsat影像提取了该岸段岸线,并进行了时空变化分析。结果表明,射阳河口以北的扁担港口—射阳河口岸段仍处于侵蚀状态,呈现侵蚀—淤积—缓慢侵蚀的变化格局,40 a间侵蚀面积为12.6 km2,淤积面积为1.0 km2;射阳河口以南的射阳河口—斗龙港口岸段处于淤积的态势,呈现淤积—快速淤积—缓慢淤积的格局,40 a间淤积的面积为223.1 km2,仅在2000~2013年间该岸段北部出现了侵蚀。结论是虽然射阳河口以南岸段仍总体处于淤积的过程中,但是近年来江苏海岸的侵蚀范围已经扩展到了射阳河口以南,这证明了江苏海岸侵蚀岸段有进一步扩大的趋势。 相似文献
15.
Numerical study of shoreline changes by emergency beach nourishment project at the Middle Beach of Beidaihe, China 总被引：1，自引：1，他引：0
ZHANG Yu HE Lulu KUANG Cuiping PAN Yi GU Jie YANG Yanxiong ZHANG Jiabo 《海洋学报(英文版)》2012,31(1):125-133
Beach nourishment is a common coastal management strategy used to protect beach from erosion along the sandy coastlines. This method has been successfully applied to an emergency project at the West Beach of Beidaihe in the summer of 2008 and the full West Beach nourishment project in 2009-2010, which is the direct base of this study. Some basic information about the emergency engineering area at the Middle Beach is firstly described. The shoreline change of this area, including the analysis of beach width in five monitoring profiles in the bathing places of Middle Beach, is then discussed. After that a numerical model based on one-line theory is established and the numerical results agree well with the measured shorelines, which indicates that the model is appropriate and is qualified to predict the shoreline change of the Middle Beach. With the same model and parameters, long-term performance of the project is predicted, and the result shows that without follow-up nourishment and project, the bathing places can remain suitable for bathing for about 10 a. It is suggested to nourish the beach in time and carry out the beach nourishment project for the full Middle Beach in Beidaihe. 相似文献
16.
Amaia Ruiz de Alegría-Arzaburu Adrián Pedrozo-Acuña José M. Horrillo-Caraballo Gerhard Masselink Dominic E. Reeve 《Coastal Engineering》2010
This paper describes the application of Canonical Correlation Analysis (CCA) to derive forcing–response relations between the wave climate and shoreline position on a macrotidal gravel barrier located in the southwest of the U.K., and to develop a tool to determine shoreline positions from wave records. The data sequences comprise wave climate recorded by a nearshore directional wave buoy and video-derived shorelines over a time span of one year and a half. The hydrodynamic conditions are used to determine the probability density function of wave heights and alongshore energy fluxes. These are then related to shoreline change through a CCA analysis. The CCA analysis identifies patterns of behaviour of the wave conditions and the shoreline position, and the relation between both patterns is found to provide useful information about the beach response to wave action. The analysis shows that the movement of sediment is greater at the southern end of the study area and that there is an immediate shoreline response to the wave action. In the case of coastal management it is more often the case that wave forecasts are available on a routine basis. The ability of the CCA to provide useful estimates of shorelines from wave conditions was tested by using measured waves to calculate the corresponding shoreline position from additional data at the end of the sequences. Shoreline positions determined with the CCA agreed well with the measured ones. Thus, the CCA is found to be a useful tool to determine unknown shoreline positions and support effective coastal management if good quality hydrodynamic and morphological data are available to input into the initial set-up of the technique. 相似文献
17.
海岸带地区自然岸线具有极其重要的资源价值和独特的生态价值。一些海岸的人工岸线经过整治修复或长时间的海陆相互作用，逐渐恢复了自然海岸的形态和功能。此类岸线本该被认定为新增自然岸线并严格管控，然而长期以来新增自然岸线的认定并无技术规范或标准，致使其游离于监管边缘且仍按照普通类型人工岸线的要求进行管理，一定程度上制约了海岸线的严格保护和有序利用。文章将新增自然岸线分为两类，即人工岸线整治修复成自然岸线和人工岸线自然恢复成自然岸线，并给出了典型岸线类型的认定标准。同时，提出新增自然岸线的管理要求，为推动构建科学合理的自然岸线格局提供了重要技术支撑。 相似文献
18.
Mapping shoreline changes along coastal regions is critically important in monitoring continuously rising sea surface heights due to climate change and frequent severe storms. Thus, it is especially important if the region has very high tidal ranges over very gentle tidal flats, which is a very vulnerable region. Although the various remote sensing platforms can be used to map shoreline changes, the spatial and temporal resolutions are not enough to obtain it for a short time. Accordingly, in this study we introduce the newly developed low altitude Helikite remote sensing platform to achieve much better resolutions of shorelines and a bathymetry. The Helikite stands for Helium balloon and Kite, which is a kind of aerial platform that uses the advantages of both a Helium balloon and a kite. Field experiments were conducted in the Jaebu Island, off the coast of the west Korean Peninsula in January 29, 2011. In order to extract shorelines from the consecutive images taken by the low altitude Helikite remote sensing platform, active contours without edges (ACWE) is used. Edges or boundaries exist primarily on places between one type of objective and the other. Since the hydrodynamic pressure has an effect everywhere, the locations of the waterlines can be the isobath lines. We could map several waterlines, which would enable us to complete a local bathymetry map ranges from 35 to 60 cm depth. The error resulting from applying ACWE algorithm to the imagery to determine the waterline is approximately less than 1 m. Therefore, it is very unique way to obtain such high resolutions of bathymetry with high accuracy for the regions of extremely high tidal ranges for a short time. 相似文献
19.
海岸建筑退缩线是科学有效保护和管理海岸线的重要措施之一。为促进我国海岸线资源的可持续开发利用,文章兼顾海岸线的自然和社会等属性,采用德尔菲法、层次分析法和聚类分析法相结合的方法,构建我国海岸建筑退缩线退缩距离的综合评价指标体系,提出退缩距离的计算方法,并以秦皇岛沿岸为例划定海岸建筑退缩线。研究结果表明：海岸建筑退缩线退缩距离的综合评价指标体系包括海岸线类型、海岸线开发利用类型、海洋经济效益、防灾效果和生态环境质量5类影响因素以及16项主要指标;在确定退缩线起算基线、综合评价指标分级和退缩距离等级的基础上,海岸建筑退缩线退缩距离是随综合评价值的增大而敏感性增强的连续分段函数;在秦皇岛沿岸的27个岸段中,海岸建筑退缩线的退缩距离等级分布较广,最小和最大退缩距离分别为25 m和500 m,其中河口和基岩等岸线的退缩距离较小,旅游娱乐岸线的退缩距离基本为200～300 m,保护区岸线的退缩距离较大。 相似文献
20.
Equilibrium headland-bay beach systems have been mathematically described by logarithmic, parabolic and hyperbolic curve functions. The largest system of this type reported to date has a shoreline length of about 62 km. In the present study, an apparent headland-bay system is presented which has a shoreline length of about 500 km. It was discovered on satellite images, and is located between Cabo de Santa Maria in Portugal and the coastal city of Rabat in Morocco. It appears to be controlled by long-period North Atlantic swells diffracting around Cabo São Vicente at the south-western tip of Portugal, in combination with SW–SE wind wave climates impinging on the northern shoreline of Cádiz Bay. The coast shows two marked departures from the equilibrium shoreline along its central section north and south of the Strait of Gibraltar, which are easily explained. Thus, the promontories to the north of the strait still exist because there has not been sufficient time to erode these back to the equilibrium shoreline since postglacial sea-level recovery. The coastal indentation to the south is explained by an insufficient sediment supply from terrestrial sources to facilitate the required beach accretion. Perfectly adjusted planimetric headland-bay shoreline shapes represent situations where wave orthogonals approach the coast at right angles everywhere, i.e. there is no longer any alongshore sediment transport. Equilibrium shorelines form independently of the grain size of the beach sediment, whereas morphodynamic beach states are indirectly affected by the shoreline shapes because the latter are modulated by wave period and breaker height which also control the morphodynamic response of the beach in combination with the local grain size. 相似文献