Statistical modelling of the barrier height fronting a coastal lagoon and the impact of sea-level rise

A temporal stochastic modelling method for predicting exceedance probabilities of the beach barrier elevations fronting intermittently closed and open coastal lagoons is developed. The method incorporates synthetic tides generated from measured tidal harmonics, and randomly sampled values relating to rainfall, beach face slope, lake opening period, and wave height, direction and period. Samples are derived from distributions of each of these parameters formed from standard long term data records. The method is applied to Tabourie Lake, on the south coast of New South Wales. This entrance is sheltered from the dominant wave climate by an island close to shore, the impact of which is separately assessed by phase averaged wave modelling. The barrier elevation is determined from the 2% run-up level arising from constructive waves. The sensitivity of results to a variety of assumptions is tested. The methodology is applied to determine the probabilistic distribution of barrier heights for both stationary and non-stationary (i.e. sea level rise (SLR)) scenarios. Such probabilities can be adopted in a risk based assessment of catchment flooding behind an enclosing barrier for present conditions, or provide management guidelines for future climate scenario, i.e. changes in rainfall, wave climate, sea level. The model can also be used to investigate different management strategies and how these alter the barrier elevation for given probabilities of exceedance.     

Potential for sustainable sea transport: A case study of the Southern Lomaiviti,Fiji islands

This paper outlines research on the sea transport need and potential options for the future for the islands of Gau, Batiki and Nairai, Southern Lomaiviti, Fiji. Sea transport is vital for this island group but is limited to infrequent commercial ferry services and outboard driven punts. The Fiji Government subsidises the ferries through its Shipping Franchise Scheme to ensure commercial operators service the route. The absence of commercial development within the group has meant high biodiversity and cultural values have been preserved and there are a number of projects, especially on Gau, with a common aim of building resilience or ‘climate change proofing’ the communities and their island environments. These projects are focused on supporting local communities to maintain well-being through improved reliance on local and natural assets. It is logical to add analysis of low carbon sea transport options to these initiatives. Lomaiviti has been selected as representative of a number of isolated Maritime Provinces in the Pacific. This paper is expected to pave the way for greater research in this field and assist in solving the crippling effect of the region's current fossil fuel dependency.     

未来海平面上升对江苏沿海水利工程的影响

研究探讨表明,未来海平面上升将导致江苏沿海水利工程本身风险性的显著增大,表现为工程遭受破坏程度的增强和受到破坏次数的指数性增多。海面上升还严重影响苏北沿海水利工程效用的发挥,表现为海堤防护标准的降低,抗御风暴潮的能力减少,以及沿海挡潮闸排水能力的降低,加剧这一地区的洪涝灾害。最后,为减轻未来海平面上升对苏北沿海水利工程造成的不利影响,提出了一些看法和建议。     

Coastal vulnerability in barrier islands: The high risk areas of the Ria Formosa (Portugal) system

Coastal vulnerability in barrier island systems is extremely high. The barrier island shoreline is exposed to many threats, such as storm erosion, reductions in sediment longshore drift and sea level rise. Many of these threats to coastal areas, such as Ria Formosa, are likely to increase in the near future. The main objectives of the present study are to identify the areas in the system that are at most risk by assessing the evolution of the Ria Formosa barrier island system since the 1940s, and determine which interventions would be necessary to protect these areas.The coastal vulnerability of the system was assessed based on current literature, data available from official institutions, and aerial and terrestrial in situ examination. The results obtained for the evolution of the Ria Formosa coastal system reveal that there are several vulnerable areas that have very dynamic processes, such as extremely high evolution rates of islands and inlets. Human actions that affect the whole system, namely the construction of many physical structures, are the main cause of the instability. Moreover, as several stakeholders are involved, efficient management of the coastal system is imperative. Extensive and careful interventions are urgently needed to avoid irreversible negative impacts on the barrier island system. Three types of techniques could be adopted to deal with the threats to barrier islands: hard stabilization, soft techniques, and non-structural alternatives. However, using hard techniques has many negative effects compared to soft techniques, and as a result it is necessary to remove existing structures from the areas at most risk.     

Relative Sea Level Changes in Maldives and Vulnerability of Land Due to Abnormal Coastal Inundation

Oceanic Islands in the Pacific and Indian Oceans have extremely small land areas, usually less than 500 km2, with maximum height about 4 m above sea level. The Republic of Maldives is an independent island nation in the Indian Ocean south of Sri Lanka which stretches vertically in the Indian Ocean from 07° 06'N - 0° 42'S. The land area of this island country is about 300 km2, and none of Maldives' 1190 islands has an elevation more than 3 m above sea level. In fact the Maldives has the distinction of being the flattest country on earth, making it extremely vulnerable to the effects of global warming. Of the south Asian countries, the Maldives is the most vulnerable nation, facing severe consequences as a result of global warming and sea level rise (SLR). Because of their obvious vulnerability to SLR, the Government of Maldives is very much concerned about climate change. As global warming and the related SLR is an important integrated environmental issue, the need of the hour is to monitor and assess these changes. The present article deals mainly with the analysis of the tidal and Sea Surface Temperature (SST) data observed at Male and Gan stations along the Maldives coast in the northern and southern hemispheres, respectively. The objective of the analysis is to study the trends of these parameters. Trend analysis is also performed on the corresponding air temperature data of both stations. The results show that Maldives coastal sea level is rising in the same way (rising trend) as the global sea level. The mean tidal level at Male has shown an increasing trend of about 4.1 mm/year.Similarly at Gan, near the equator,it has registered a positive trend of about 3.9 mm/year.Sea level variations are the manifestations of various changes that are taking place in the Ocean-Atmosphere system. Therefore, the variations in SST and air temperature are intimately linked to sea level rise. It is found that SST and air temperature have also registered an increasing trend at both stations. The evidence of rising trends suggest that careful future monitoring of these parameters is very much required. Tropical cyclones normally do not affect the Maldives coast. However, due to its isolated location, the long fetches in association with swells generated by storms, that originated in the far south have resulted in flooding. Thus the rising rate of sea level with high waves and flat topography have increased the risk of flooding and increased the rate of erosion and alteration of beaches.     

基于高分遥感的西沙群岛典型海岛时空变化分析

高分辨率卫星遥感技术已成为有效监测海岛动态变化的主要手段。本文以西沙群岛社区驻地海岛、领海基点所在海岛和自然保护区所在海岛为研究对象,利用 2005 年以来的高分辨率卫星遥感影像,分析了各类海岛的时空变化情况。结果表明：社区驻地海岛变化普遍较大,特别是永兴岛、赵述岛、筐仔沙洲和银屿,主要都是由于吹沙填岛和岛上开发利用活动日益增多造成的,变化主要发生在 2012 年三沙市成立之后;领海基点所在海岛和自然保护区所在海岛相对较稳定,岛上地形、地貌及植被等基本保持原有的自然状态,变化区域主要分布在各个海岛的端头,主要是由自然因素导致的。海滩岩对海岛起到了极大的保护作用,海滩岩发育好的海岛基本保持稳定状态,而没有海滩岩发育或海滩岩被破坏的海岛则变化较大。     

青岛市崂山区海岛资源的持续利用

青岛市崂山区海岛及其周围海域资源丰富,有较大的开发潜力。首先对崂山区海岛的资源特点进行了分析,并指出了制约崂山区海岛经济发展的因素,在此基础上,提出了合理保护与利用崂山区的海岛资源的对策和建议,为崂山区充分利用海岛的自然资源和加速海岛经济与社会的可持续发展提供了科学依据。     

Relative Sea Level Changes in Maldives and Vulnerability of Land Due to Abnormal Coastal Inundation

Oceanic Islands in the Pacific and Indian Oceans have extremely small land areas, usually less than 500 km2, with maximum height about 4 m above sea level. The Republic of Maldives is an independent island nation in the Indian Ocean south of Sri Lanka which stretches vertically in the Indian Ocean from 07° 06'N - 0° 42'S. The land area of this island country is about 300 km2, and none of Maldives' 1190 islands has an elevation more than 3 m above sea level. In fact the Maldives has the distinction of being the flattest country on earth, making it extremely vulnerable to the effects of global warming. Of the south Asian countries, the Maldives is the most vulnerable nation, facing severe consequences as a result of global warming and sea level rise (SLR). Because of their obvious vulnerability to SLR, the Government of Maldives is very much concerned about climate change. As global warming and the related SLR is an important integrated environmental issue, the need of the hour is to monitor and assess these changes. The present article deals mainly with the analysis of the tidal and Sea Surface Temperature (SST) data observed at Male and Gan stations along the Maldives coast in the northern and southern hemispheres, respectively. The objective of the analysis is to study the trends of these parameters. Trend analysis is also performed on the corresponding air temperature data of both stations. The results show that Maldives coastal sea level is rising in the same way (rising trend) as the global sea level. The mean tidal level at Male has shown an increasing trend of about 4.1 mm/year.Similarly at Gan, near the equator,it has registered a positive trend of about 3.9 mm/year.Sea level variations are the manifestations of various changes that are taking place in the Ocean-Atmosphere system. Therefore, the variations in SST and air temperature are intimately linked to sea level rise. It is found that SST and air temperature have also registered an increasing trend at both stations. The evidence of rising trends suggest that careful future monitoring of these parameters is very much required. Tropical cyclones normally do not affect the Maldives coast. However, due to its isolated location, the long fetches in association with swells generated by storms, that originated in the far south have resulted in flooding. Thus the rising rate of sea level with high waves and flat topography have increased the risk of flooding and increased the rate of erosion and alteration of beaches.     

海平面上升的风险评估研究进展与展望

海岸带是海陆交互作用的集中区域,人类活动密集,面对未来海平面上升带来的影响具有敏感性和脆弱性。评估未来海平面上升对海岸带的风险,具有理论与实际意义。根据海平面上升风险评估研究框架,总结了海平面上升、海岸侵蚀、风暴潮淹没、海水入侵、湿地丧失等方面的研究现状,在此基础上,分析了目前研究存在的不足,并提出了海平面上升风险评估未来研究的关键问题。     

Holocene evolution of Apalachicola Bay,Florida

A program of geophysical mapping and vibracoring was conducted to better understand the geologic evolution of Apalachicola Bay. Analyses of the geophysical data and sediment cores along with age control provided by 34 AMS ¹⁴C dates on marine shells and wood reveal the following history. As sea level rose in the early Holocene, fluvial deposits filled the Apalachicola River paleochannel, which extended southward under the central part of the bay and seaward across the continental shelf. Sediments to either side of the paleochannel contain abundant wood fragments, with dates documenting that those areas were forested at 8,000 ¹⁴C years b.p. As sea level continued to rise, spits formed of headland prodelta deposits. Between ∼6,400 and ∼2,500 ¹⁴C years b.p., an Apalachicola prodelta prograded and receded several times across the inner shelf that underlies the western part of the bay. An eastern deltaic lobe was active for a shorter time, between ∼5,800 and 5,100 ¹⁴C years b.p. Estuarine benthic foraminiferal assemblages occurred in the western bay as early as 6,400 ¹⁴C years b.p., and indicate that there was some physical barrier to open-ocean circulation and shelf species established by that time. It is considered that shoals formed in the region of the present barrier islands as the rising sea flooded an interstream divide. Estuarine conditions were established very early in the post-glacial flooding of the bay.     

广西海岛海岸线变迁与动态变化及影响分析

海岛不仅具有很高的资源、生态和经济价值,而且对维护国家海洋权益具有重大意义。近年来,全球气候异常,海平面上升、海水入侵的出现改变了岛陆岸线和岛滩的生态环境,同时也使高程较低的海岛面临存在的威胁。文章通过选取广西省具有代表性的海岛,研究了海岛海岸线的变迁与动态变化的成因,同时,对海岛岸线变迁作出了预测及影响分析。     

Coastal erosion and village relocation: a Colombian case study

Because of its tectonic setting, the Pacific coast of Colombia is subject to a variety of geological hazards, including earthquakes, tsunamis and associated phenomena such as regional and local coastal subsidence, flooding and soil liquefaction. Erosional trends are prevalent along much of the 700 km long, low barrier island's shorelines of the Pacific littoral and land losses are enhanced by factors such as 30 cm regional sea level rises associated to the occurrence of El Niño. Marine erosion is threatening more seashore littoral villages and worsening the already difficult socioeconomic conditions of most part of the inhabitants. Because of diverse and strong motivations to stay near the sea, the responses of barriers island's inhabitants to marine erosion has consisted in most cases of repetitive in-shore and along-shore directed relocations of villages, rather than definitive abandonment of the islands. In the long run, this procedure only has postponed the problem and led to repetitive relocations and economical losses. The recent inland relocation of El Choncho village, on the San Juan River delta, illustrates a different response to marine erosion. Although a new along-shore relocation was physically possible, inhabitants decided to abandon the barrier island and migrate to an interior, ancient beach ridge complex, applying a prudent solution which will be the most appropriate for other threatened villages of the Pacific littoral. A detailed geomorphologic mapping program must be conducted in order to identify appropriate sites for inland relocation of existing villages on the barriers islands of the Colombian Pacific coast.     

Integrated coastal resources management and community participation in a small island setting

The concept of integrated coastal zone management must be rethought to adapt it to the geography and social conditions of small islands. Because of their size, all small islands are in the coastal zone. Defining the whole of the island and its coastal waters as the management area may weaken a program's effectiveness. An alternative may be to adapt special area management planning to the socio-spatial organization found on small islands. Social conditions on islands, where people live in relatively small cohesive communities, makes resource user participation in planning and management particularly germane. This paper outlines an argument for small islands to use participation as a central strategy of coastal management based on experience with natural resource management efforts on the island of Pohnpei in the Federated States of Micronesia.     

岬湾海岸中人工岛建设对岬角涡旋及海湾地形冲淤的影响——以海南岛铺前湾为例

岬湾海岸中一般在岬角的右侧与左侧（面向大海方向）分别发育顺时针与逆时针涡流。这些涡流的存在对泥沙输运、海底地形演变、污染物扩散等都具有重要影响。而在海洋中岛屿的存在将产生局部的岛后尾流。如岛屿与岬角距离较近,岛后尾流可能与岬角涡旋相互作用,反之则相互影响较小。本文以海南岛铺前湾为例,研究在岬湾海岸中湾口处的人工岛建设对湾内涡旋的影响,并进一步分析人工岛建设对整个海湾海底冲淤变化的效应。本项研究主要采用COAWST模型进行研究。结果表明,大潮期在海湾内发育大范围的顺时针涡旋,小潮期涡旋发育不明显,以东向余流为主。人工岛建设并未影响整个海湾的涡旋结构,但人工岛分隔了湾内顺时针涡旋,且在周围产生局部的逆时针与顺时针涡旋。海底冲淤变化的基本格局为湾内以淤积为主,人工岛建设加强了这种趋势,但在人工岛与岸线之间的狭窄通道内,海底出现冲刷。本项研究对岬湾海岸的科学开发管理具有一定意义。     

Modifications of the shore line in the Society islands (French Polynesia)

The people living on the mountainous islands of the Society archipelago have the good luck to benefit from peaceful lagoon waters. The narrow littoral plain is protected from the assaults of the sea by a barrier-reef and the temptation to live by the sea-side is strong. It is all the more stronger as the mountains, although splendid, are not easy places to settle. As an interface between the terrestrial and lagoon environments, the shore line of the mountainous islands is mainly occupied by high vegetation in its natural configuration. Rocks, sandy beaches and muddy areas can be accounted for by geomorphologic factors directly linked to the transformation process of each mountainous island becoming an atoll. While the shore line in the mountainous islands of the Society archipelago is mostly natural, more than 40% has been directly modified by man. But nevertheless this anthropogenization does not correlate with population density or economic development. It results from the complex interactions between human and natural factors. Embankment works and excavating coral materials from the fringing reef are particularly destructive activities for the environment. Current concerns related to rising sea levels emphasized the quality of the shore line for human activities and development of the littoral in the future. Only joint management encompassing the lagoon and terrestrial environments will maintain the natural and human balances, and thus, the harmonious development of the islands’ populations.     

Studies on island intertidal benthic ecology in Fujian

lNreomicrlowIntertidal zone is an important type of wetIand easystem on the earth as it is in the tranai-tion zone between 1and and the and subject to frequent human interferences. Since the inter-tidal sone is subject to a1ternative physical and chemical actions of land and as, the intertidalzone has a compticated and changeable environment. The studies on intertidal zon ecobeyhave always attracted much attention for the past decades (Stephensons, l972; MOrtons,l983: Huang and Zhu, l998; Y…     

Holocene sedimentation of a wave-dominated barrierisland shoreline: Cape Lookout, North Carolina

The sedimentary record of 130 km of microtidal (0.9 m tidal range) high wave energy (1.5 m average wave height) barrier island shoreline of the Cape Lookout cuspate foreland has been evaluated through examination of 3136 m of subsurface samples from closely spaced drill holes. Holocene sedimentation and coastal evolution has been a function of five major depositional processes: (1) eustatic sea-level rise and barrier-shoreline transgression; (2) lateral tidal inlet migration and reworking of barrier island deposits; (3) shoreface sedimentation and local barrier progradation; (4) storm washover deposition with infilling of shallow lagoons; and (5) flood-tidal delta sedimentation in back-barrier environments.

Twenty-five radiocarbon dates of subsurface peat and shell material from the Cape Lookout area are the basis for a late Holocene sea-level curve. From 9000 to 4000 B.P. eustatic sea level rose rapidly, resulting in landward migration of both barrier limbs of the cuspate foreland. A decline in the rate of sea-level rise since 4000 B.P. resulted in relative shoreline stabilization and deposition of contrasting coastal sedimentary sequences. The higher energy, storm-dominated northeast barrier limb (Core and Portsmouth Banks) has migrated landward producing a transgressive sequence of coarse-grained, horizontally bedded washover sands overlying burrowed to laminated back-barrier and lagoonal silty sands. Locally, ephemeral tidal inlets have reworked the transgressive barrier sequence depositing fining-upward spit platform and channel-fill sequences of cross-bedded, pebble gravel to fine sand and shell. Shoreface sedimentation along a portion of the lower energy, northwest barrier limb (Bogue Banks) has resulted in shoreline progradation and deposition of a coarsening-up sequence of burrowed to cross-bedded and laminated, fine-grained shoreface and foreshore sands. In contrast, the adjacent barrier island (Shackleford Banks) consists almost totally of inlet-fill sediments deposited by lateral tidal inlet migration. Holocene sediments in the shallow lagoons behind the barriers are 5–8 m thick fining-up sequences of interbedded burrowed, rooted and laminated flood-tidal delta, salt marsh, and washover sands, silts and clays.

While barrier island sequences are generally 10 m in thickness, inlet-fill sequences may be as much as 25 m thick and comprise an average of 35% of the Holocene sedimentary deposits. Tidal inlet-fill, back-barrier (including flood-tidal delta) and shoreface deposits are the most highly preservable facies in the wave-dominated barrier-shoreline setting. In the Cape Lookout cuspate foreland, these three facies account for over 80% of the sedimentary deposits preserved beneath the barriers. Foreshore, spit platform and overwash facies account for the remaining 20%.     

Using Shoreline Video Assessment for coastal planning and restoration in the context of climate change in Kien Giang,Vietnam

Kien Giang, bordering Cambodia in the Mekong River Delta, is one of the two most vulnerable provinces in the region to coastal erosion and flooding. Coastal protection can conflict with current land use and economic development activities. The conditions of the mangrove forest and mainland coastline of the Kien Giang province were assessed using the Shoreline Video Assessment Method (SVAM) backed up with information from satellite images. Half of the 206 km Kien Giang coastline has been eroded or is being eroded. Protective mangrove forests naturally occurred in 74% of the coastline but have been under threat from illegal cutting, erosion and coastal retreat. Accurate information on the state of the coastline and mangrove forest health provided invaluable data for developing a new coastal rehabilitation plan to guard against future sea level rise. In contrast to the current boundary management of land and natural resources, this plan divided the provincial coastline into 19 sections based on the landscape condition and exposure to erosion. Priority strategic actions for erosion management, mangrove restoration and sustainable livelihood development for local communities for each section of coast were developed based on an integrated cross sectoral approach and practical experience in the Conservation and Development of the Kien Giang Biosphere Reserve Project.

     

山东沿海岛屿概况及其开发

山东沿海共有305个岛屿,大部分岛屿的面积小于O.1km~2。,高度小于20m。按岩性分为基岩岛(包括岛、群岛和陆连岛)和冲积沙岛(包括沙岛和贝壳沙岛)。根据海岛的不同特点,可综合开发为海珍品基地和旅游避暑胜地。