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1.
The Charisma of Coastal Ecosystems: Addressing the Imbalance   总被引：1，自引：0，他引：1  
Coastal ecosystems including coral reefs, mangrove forests, seagrass meadows, and salt marshes are being lost at alarming rates, and increased scientific understanding of causes has failed to stem these losses. Coastal habitats receive contrasting research effort, with 60% of all of the published research carried out on coral reefs, compared to 11–14% of the records for each of salt marshes, mangrove forests, and seagrass meadows. In addition, these highly connected and interdependent coastal ecosystems receive widely contrasting media attention that is disproportional to their scientific attention. Seagrass ecosystems receive the least attention in the media (1.3% of the media reports) with greater attention on salt marshes (6.5%), considerably more attention on mangroves (20%), and a dominant focus on coral reefs, which are the subject of three in every four media reports on coastal ecosystems (72.5%). There are approximately tenfold lower reports on seagrass meadows in the media for every scientific paper published (ten), than the 130–150 media reports per scientific paper for mangroves and coral reefs. The lack of public awareness of losses of less charismatic ecosystems results in the continuation of detrimental practices and therefore contributes to continued declines of coastal ecosystems. More effective communication of scientific knowledge about these uncharismatic but ecologically important coastal habitats is required. Effective use of formal (e.g., school curricula, media) and informal (e.g., web) education avenues and an effective partnership between scientists and media communicators are essential to raise public awareness of issues, concerns, and solutions within coastal ecosystems. Only increased public understanding can ultimately inform and motivate effective management of these ecologically important coastal ecosystems.  相似文献   

2.
After the 2004 Sumatra?CAndaman tsunamigenic earthquake, waters from the ocean moved upstream along rivers, bays, harbors, and lagoons and inundated many coastal and inland locations in the southern, eastern, and northern parts of Sri Lanka. The tsunami waters were observed to move upwards inland and then recede downwards to the ocean after varying inundation periods in different coastal areas. Subsequent massive tsunami waves came with the wave height varying from 3 to 8?m inland with speed of about 30?C40?kmph. The oceanic waves carrying heterogeneous sediments with water deposited them in coastal as well as inland locations about 1?km from the present coastline. Given the chaotic nature of tsunami oceanic waves, pre-tsunami deposits, such as beach sands, debris from coral reefs and buildings, parts of vehicles and ships, and tree trunks are found incorporated in authentic tsunami sediments. Thus, the texture, structure, and composition of sediments deposited by tsunami waters differed from one location to another. Therefore, in identifying paleo-tsunami sediments, care was taken to compare them with diagnostic unmixed uncontaminated recent tsunami sediments having characteristic textures and marine microfossil assemblages, such as foraminifera, radiolarians, and diatoms where preserved in coastal depressions. The radiocarbon ages of the carbonate and the organic fractions of these sediments are stratigraphically inconsistent, indicating mixing of sediments by the tsunami waves. The concentrations of organic carbon and nitrogen and their isotopic signatures confirm marine origin of these sediments.  相似文献   

3.
Coastal ecosystems such as mangroves fringing tropical coastlines have been recognized as natural protectors of the coastal areas against destructive attack of a tsunami. In this paper, the authors aim to investigate the interaction of a tsunami wave on a typical mangrove forest and to determine its performance in reducing the run-up. A laboratory experiment using a hydraulic flume with a mangrove forest model was carried out in which tests were conducted by varying the vegetation widths of 0, 1, 2 and 3?m and average densities of 8, 6 and 4 trees per 100?cm2 using a scale ratio of 1:100. Two conditions of water levels were considered in the experiments at several tsunami wave heights between 2.4 and 14?cm. The dam break method used in the experiments produced two types of waves. At low water condition, a bore was developed and subsequently, a solitary wave was produced during high water. The results of the experiments showed that in general, vegetation widths and densities demonstrate a dampening effect on tsunami run-up. A larger vegetation width was found to be more effective in dissipating the wave energy. The first 1?m width of mangrove forest could reduce 23?C32?% during high water and 31?C36?% during low water. Increasing the mangrove forest width to 2 and 3?m could further increase the average percentage of run-up reduction by 39?C50?% during high water and 34?C41?% during low water condition. It was also observed that densities of the mangrove forest do not influence the run-up reduction as significantly as the forest widths. For mangrove forest densities to be significantly enough to reduce more tsunami run-up, an additional density of 4 trees/100?m2 needs to be provided. The experiments also showed that mangrove roots are more effective in reducing the run-up compared to the trunks and canopies. The experiments managed to compare and present the usefulness of mangrove forests in dissipating wave energy and results produced are beneficial for initiating design guidelines in determining setback limits or buffer zones for development projects in mangrove areas.  相似文献   

4.
The statigraphy in 25 coastal lakes shows that most of the Norwegian coastline was impacted by a large tsunami about 7200 14C BP. The methodology has been to core a staircase of lake basins above the contemporary sea level in several areas and to map the tsunami deposit to its maximum elevation. The tsunami was identified in the sedimentary record as an erosional unconformity overlain by graded or massive sand with shell fragments, followed by redeposited organic detritus. The greatest recorded runup along the coast (10–11 m above high tide) is found in areas most proximal to the Storegga slide scar on the Norwegian continental slope (Sunnmøre). To the north and south, runup is less, about 6–7 m at Bjugn (250 km north of Sunnmøre) and about 3–5 m in Austrheim (200 km to the south of Sunnmerre). This runup pattern supports the suggestion that the tsunami was generated by the Second Storegga Slide. The recorded runup heights are consistent within and between the investigated areas, and imply that the tsunami wave was not significantly influenced by the local topography, suggesting a very long wave length. The mapped runup estimates are in good agreement with a numerical model of the tsunami generated by the Second Storegga slide, and indicate that the slide was a single major event rather than a set of smaller slides.  相似文献   

5.
Sea surface temperature trends in Kuwait Bay,Arabian Gulf   总被引：1，自引：0，他引：1  
The magnitude 8.1 earthquake and subsequent tsunami killed 52 people when it hit the Solomon Islands on 2 April 2007. That number would have likely been considerably higher were it not for the appropriate reaction of the indigenous coastal populations and a helpful physical geography. Buffering coral reefs reflected some wave energy back to sea, reducing the power of the wave. Hills a short distance behind the coastal villages provided accessible havens. Despite this beneficial physiography, immigrant populations died at disproportionately high rates in comparably damaged areas because they did not recognize the signs of the impeding tsunami. The indigenous population of Tapurai, which lacks a steep barrier reef to reflect the incoming energy, experienced a much more powerful wave, and the population suffered heavy losses. Indigenous knowledge as an integral tool in basin wide tsunami warning systems has the potential to mitigate disasters in the near field. Community-based disaster management plans must be cognizant of educating diverse populations that have different understandings of their environment.  相似文献   

6.
热带生物海岸对全球变化的响应   总被引：2，自引：0，他引：2  
张乔民 《第四纪研究》2007,27(5):834-844
以热带生物海岸现代过程研究成果为基础,结合国内外相关资料,分析我国红树林海岸和珊瑚礁海岸对全球变暖、海平面上升、大气CO2浓度升高和海洋酸化的响应.其中,全球变暖和大气CO2浓度升高总体上有利于红树林生长发育,海平面上升对红树林和珊瑚礁的影响取决于红树林潮滩淤积速率和珊瑚礁礁坪堆积速率与海平面上升速率之间的对比关系.海平面加速上升将威胁部分红树林、珊瑚礁及其后的海岸堤防.全球变暖海表异常高温导致珊瑚白化、海洋酸化导致珊瑚和珊瑚藻钙化率降低将成为21世纪珊瑚礁的重大威胁.全球变化的不确定性和生态系统响应机制仍然有待进一步研究.主要是人类不合理开发活动导致目前红树林和珊瑚礁的广泛严重破坏,加强海岸带综合管理和生态环境保护,加强生态系统恢复重建,是有效适应本世纪全球变化影响的重要措施.  相似文献   

7.
Although hurricane disturbance is a natural occurrence in mangrove forests, the effect of widespread human alterations on the resiliency of estuarine habitats is unknown. The resiliency of mangrove forests in southwest Florida to the 2004 hurricane season was evaluated by determining the immediate response of mangroves to a catastrophic hurricane in areas with restricted and unrestricted tidal connections. The landfall of Hurricane Charley, a category 4 storm, left pronounced disturbances to mangrove forests on southwest Florida barrier islands. A significant and negative relationship between canopy loss and distance from the eyewall was observed. While a species-specific response to the hurricane was expected, no significant differences were found among species in the size of severely impacted trees. In the region farthest from the eyewall, increases in canopy density indicated that refoliation and recovery occurred relatively quickly. There were no increases or decreases in canopy density in regions closer to the eyewall where there were complete losses of crown structures. In pre-hurricane surveys, plots located in areas of management concern (i.e., restricted connection) had significantly lower stem diameter at breast height and higher stem densities than plots with unrestricted connection. These differences partially dictated the severity of effect from the hurricane. There were also significantly lower red mangrove (Rhizophora mangle) seedling densities in plots with restricted connections. These observations suggest that delays in forest recovery are possible in severely impacted areas if either the delivery of propagules or the production of seedlings is reduced by habitat fragmentation.  相似文献   

8.
Ten years after the Indian Ocean tsunami in 2004 and following a long process of rehabilitation and reconstruction, Aceh has finally recovered. After the tsunami, Aceh experienced a dramatic migration of its coastal population away from the city; however, after 10 years, the population has mostly recovered. As new houses have been built and new economic activities commenced in the coastal areas, there is now concern regarding potential future tsunami risks for the city. The initial rehabilitation and reconstruction plan sought to prevent the construction of any new houses 500 m from the coastline; however, this failed to happen. This paper elucidates the reasons why these new coastal communities chose their new housing areas and examines the coastal land use changes around Banda Aceh 10 years after the Indian Ocean tsunami. Questionnaires were distributed to 457 respondents, and multiple logistic regressions were used to examine the reasons for household location selection and whether a possible future tsunami was a deciding factor. To examine the coastal land use changes, a series of aerial images from the Banda Aceh coastal area were digitised. It was found that tsunami history was not a major factor in new household selection; rather, rents and land prices, distance from work, and family connections were the top three reasons motivating households to select new living places. These changes and new settlements have given the city’s disaster management agency the challenge of building more emergency infrastructure in the coastal areas.  相似文献   

9.
Rapid development of shrimp farming may lead to unrecognized and undesirable changes of land cover/land use patterns in coastal areas. Of special concern is the loss of mangrove forest in coastal areas such as Quang Ninh, Vietnam, which is adjacent to the World Heritage-listed Ha Long Bay. Understanding the status and changes of land cover/land use for coastal shrimp farms and mangrove forests can support environmental protection and decision-making for sustainable development in coastal areas. Within this context, this paper uses the 1999/2001 Landsat ETM+ and the 2008 ALOS AVNIR-2 imagery to investigate the contraction and expansion of shrimp farms and mangrove forests in coastal areas of Ha Long and Mong Cai, which now have a high concentration of intensive and semi-intensive shrimp farms. Images were separately analyzed and classified before using post-classification comparisons to detect land cover/land use changes in the study area. The results of this study found that the area of mangrove forest has been reduced by an estimated 927.5 ha in Ha Long and 1,144.4 ha in Mong Cai, while shrimp farming areas increased by an estimated 1,195.9 and 1,702.5 ha, respectively, over the same period. The majority of shrimp farms in Mong Cai were established at the expense of mangrove forest (49.4 %) while shrimp farms in Ha Long were mainly constructed on areas previously occupied by bare ground (46.5 %) and a significant proportion also replaced mangroves (23.9 %). The remarkable rate of mangrove loss and shrimp farming expansion detected in this study, over a relatively short time scale indicate that greater awareness of environmental impacts of shrimp farm expansion is required if this industry is to be sustainable, the important estuarine and coastal marine ecosystems are to be protected over the long term, and the capturing and storing of carbon in mangrove systems are to be enhanced for global climate change mitigation and for use as carbon offsets.  相似文献   

10.
Laboratory experiments were carried out to study tsunami flow dynamics in the presence of patchy macro-roughness, representing coastal forest, on a 1:10 steep beach. The experimental setup included four cross-shore rows of roughness patches affixed to the dry beach in a staggered array, such that 12 % of the staggered array region had higher roughness. The flow field during run-up and withdrawal was quantified using point measurements of velocity and flow depth at 20 locations, while high-resolution video was used to track bore position during run-up. Data analysis revealed that while inundated area was marginally impacted when patchy roughness was present, flow depths and flow force were, respectively, increased by more than 40 and 30 % in some areas within the patch array; a decrease in flow force was also observed in some areas. Alongshore variation in flow depth, induced by the roughness patches, was most pronounced during withdrawal. These findings suggest that patchy macro-roughness, like that created by coastal forest, will simultaneously lead to increased protection in some areas and decreased protection in others.  相似文献   

11.
Tsunami deposits have been found at more than 60 sites along the Cascadia margin of Western North America, and here we review and synthesize their distribution and sedimentary characteristics based on the published record. Cascadia tsunami deposits are best preserved, and most easily identified, in low-energy coastal environments such as tidal marshes, back-barrier marshes and coastal lakes where they occur as anomalous layers of sand within peat and mud. They extend up to a kilometer inland in open coastal settings and several kilometers up river valleys. They are distinguished from other sediments by a combination of sedimentary character and stratigraphic context. Recurrence intervals range from 300–1000 years with an average of 500–600 years. The tsunami deposits have been used to help evaluate and mitigate tsunami hazards in Cascadia. They show that the Cascadia subduction zone is prone to great earthquakes that generate large tsunamis. The inclusion of tsunami deposits on inundation maps, used in conjunction with results from inundation models, allows a more accurate assessment of areas subject to tsunami inundation. The application of sediment transport models can help estimate tsunami flow velocity and wave height, parameters which are necessary to help establish evacuation routes and plan development in tsunami prone areas.  相似文献   

12.
Co-seismic phenomena along the south coastline included liquefaction, subsidenceand tsunami. Construction on areas composed of fluvial and alluvial sediments aswell as unconsolidated fill increased the risk by creating potential for amplificationof seismic waves. Cyclic mobility liquefaction was common along the coastline, andlevel-ground liquefaction was observed. Flow liquefaction is held forth as a possibilityin the Deirmendere submarine landslide. Damage to structures was markedly more in areas of unconsolidated sediments. One or more tsunami struck immediately after the event; the uniformity of tsunami impact indicating a wave coming from 310° suggests that submarine faulting was the major source of tsunami. Over 800,000 m2 of subsidence resulted from sediment slumping, fault controlled subsidence, and possibly post-liquefaction sediment compaction. After a brief period of post-event abandonment, reclamation and use of coastal areas is well underway. This creates a tension between human desires pushing for quick and inexpensive re-inhabitation of the coastal areas, and the needs for zoning and building codes for risk reduction. In this high-risk area suchcontrary cultural mandates cannot yield ideal results. It is suggested that an alternativemodel of immediate post-event creation of parks and natural areas that would yield benefit is preferable in coastal areas rather than the enforcement approach currently favored.  相似文献   

13.
Natural disasters can neither be predicted nor prevented. Urban areas with a high population density coupled with the construction of man-made structures are subjected to greater levels of risk to life and property in the event of natural hazards. One of the major and densely populated urban areas in the east coast of India is the city of Chennai (Madras), which was severely affected by the 2004 Tsunami, and mitigation efforts were severely dampened due to the non-availability of data on the vulnerability on the Chennai coast to tsunami hazard. Chennai is prone to coastal hazards and hence has hazard maps on its earth-quake prone areas, cyclone prone areas and flood prone areas but no information on areas vulnerable to tsunamis. Hence, mapping has to be done of the areas where the tsunami of December 2004 had directly hit and flooded the coastal areas in Chennai in order to develop tsunami vulnerability map for coastal Chennai. The objective of this study is to develop a GIS-based tsunami vulnerability map for Chennai by using a numerical model of tsunami propagation together with documented observations and field measurements of the evidence left behind by the tsunami in December 2004. World-renowned and the second-longest tourist beach in the world “Marina” present in this region witnessed maximum death toll due to its flat topography, resulting in an inundation of about 300 m landward with high flow velocity of the order of 2 m/s.  相似文献   

14.
The Storegga tsunami, dated in Norway to 8150±30 cal. years BP, hit many countries bordering the North Sea. Run-ups of >30 m occurred and 1000s of kilometres of coast were impacted. Whilst recent modelling successfully generated a tsunami wave train, the wave heights and velocities, it under-estimated wave run-ups. Work presented here used luminescence to directly date the Storegga tsunami deposits at the type site of Maryton, Aberdeenshire in Scotland. It also undertook sedimentological characterization to establish provenance, and number and relative power of the tsunami waves. Tsunami model refinement used this to better understand coastal inundation. Luminescence ages successfully date Scottish Storegga tsunami deposits to 8100±250 years. Sedimentology showed that at Montrose, three tsunami waves came from the northeast or east, over-ran pre-existing marine sands and weathered igneous bedrock on the coastal plain. Incorporation of an inundation model predicts well a tsunami impacting on the Montrose Basin in terms of replicate direction and sediment size. However, under-estimation of run-up persisted requiring further consideration of palaeotopography and palaeo-near-shore bathymetry for it to agree with sedimentary evidence. Future model evolution incorporating this will be better able to inform on the hazard risk and potential impacts for future high-magnitude submarine generated tsunami events.  相似文献   

15.
Study on contamination of tsunami sediments deposited on 26 December 2004 conducted shortly after the tsunami in coastal zone of Thailand revealed elevated contents of salts in water-soluble and some heavy metals and arsenic in bioavailable fractions (Szczuciński et al. in Env Geol 49:321–331, 2005). Few months later rainy season started and effected in total rainfall of over 3,300 mm. This paper presents results of survey repeated 1 year after the tsunami. To assess the effects of rainy season on mobilization of previously determined potential contaminants, the same locations were sampled again and analysed with the same methods. The tsunami deposit layer was well preserved but in many locations the sediments were coarser than just after tsunami due to washing out of finer fractions. The water-soluble salts contents were strongly reduced after the rainy season. However, the concentrations of acid leachable heavy metals and metalloids were still elevated in comparison to reference sample from an area not impacted by tsunami. It is possible that the metals and metalloids are successively moved to more bioavailable fraction from forms which were more resistant to mobilization.  相似文献   

16.
Local Tsunami Warning in the Pacific Coastal United States   总被引：2，自引：1，他引：1  
Coastal areas are warned of a tsunami by natural phenomena and man-made warning systems. Earthquake shaking and/or unusual water conditions, such as rapid changes in water level, are natural phenomena that warn coastal areas of a local tsunami that will arrive in minutes. Unusual water conditions are the natural warning for a distant tsunami. Man-made warning systems include sirens, telephones, weather radios, and the Emergency Alert System. Man-made warning systems are normally used for distant tsunamis, but can be used to reinforce the natural phenomena if the systems can survive earthquake shaking. The tsunami warning bulletins provided by the West Coast/Alaska and Pacific Tsunami Warning Centers and the flow of tsunami warning from warning centers to the locals are critical steps in the warning process. Public knowledge of natural phenomena coupled with robust, redundant, and widespread man-made warning systems will ensure that all residents and tourists in the inundation zone are warned in an effective and timely manner.  相似文献   

17.
The tsunami run-up, inundation and damage pattern observed along the coast of Tamilnadu (India) during the deadliest Indian Ocean tsunami of December 26, 2004 is documented in this paper. The tsunami caused severe damage and claimed many victims in the coastal areas of eleven countries, bordering the Indian Ocean. Along the coast of Indian mainland, the damage was caused by the tsunami only. Largest tsunami run-up and inundation was observed along the coast of Nagapattinam district and was about 10–12 m and 3.0 km, respectively. The measured inundation data were strongly scattered in direct relationship to the morphology of the seashore and the tsunami run-up. Lowest tsunami run-up and inundation was measured along the coast of Thanjavur, Puddukkotai and Ramnathpuram districts of Tamilnadu in the Palk Strait. The presence of shadow of Sri Lanka, the interferences of direct/receded waves with the reflected waves from Sri Lanka and Maldive Islands and variation in the width of continental shelf were the main cause of large variation in tsunami run-up along the coast of Tamilnadu.  相似文献   

18.
2004年12月26日,由于欧亚板块的碰撞,40年以来最大的地震灾害发生在印度洋。地震诱发的海啸影响到Nangroe Aceh Darussalam省的许多城市,包括省会城市班达阿齐。在这地区共有超过12万人死亡,100万人无家可归。基于遥感数据的分析表明,有12万亩的土地受到了灾害。在班达阿齐市,鱼塘、住宅用地和保护区的变化是这一地区最显著的土地利用/覆盖变化,受灾前后这些用地类型的面积相应的变化了61.5%、57.8% 和77.6%。目前,印度尼西亚中央政府正在计划一个新的海岸带土地利用规划,在原来密集的海岸带建立一个缓冲区（约距海岸带2 km）。政府已经要求许多海岸带的社区代表与非政府组织参与到决策的过程中。 为了选择并采取最佳的土地利用方式,海啸灾害后的海岸带规划应该包括一些重要的基本要素。本研究主要关注作为该省社会经济活动中心的班达阿齐市。检测了由于海啸灾害造成的土地利用/覆盖变化（包括物理破坏）,特别是农业用地和居住区用地的变化,并且分析了受灾村落的不同类型及灾害对社会经济活动造成的影响。此外,还为政府以及当地居民在灾后的规划中选择更为可持续的空间布局方案提出了建议。  相似文献   

19.
Coastal vegetation is widely recognized to reduce tsunami damage to people and buildings, and it has been studied recently because it requires relatively little capital investment compared with artificial measures, provides human-friendly beach fronts, and enhances inter-relationships with other ecological systems. However, the tsunami caused by the Great East Japan Earthquake at 14:46 JST on March 11, 2011, with a magnitude of 9.0 and epicenter 129?km east of Sendai, broke most of the sea wall (tsunami gates, large embankments) and caused catastrophic damage to coastal forests in the Tohoku and Kanto districts of Japan. A field survey was conducted to elucidate the critical breaking condition of Japanese coastal pine trees. Tree-trunk breakage was observed when the sea embankment was washed out or when there was no sea embankment and the tree was under strong inertia force or impact force by debris. Even though the trunk bending and breaking phenomena are different, statistical analysis showed that the critical diameters for trunk bending and trunk breaking were not very different. The overturning phenomenon is a little more complex than trunk breaking because the resistive force is a function of the substrate and root anchorage. An equation to determine the critical diameters for trunk bending, trunk breaking, and overturning was derived as a function of tsunami water depth, soil-root strength, and the hydrodynamic parameter (H D ) formulated by Froude number, drag coefficient, and the ratio of impact force to drag force considering the physical mechanisms to resist the tsunami. Trunk bending and breaking were closely related to tsunami water depth and the hydrodynamic parameter (H D ), but tree overturning was found to be more site specific, and the root-soil strength greatly affected the critical value. The proposed critical diameter equation and its coefficient are useful for the design of an inland forest of pine trees that can trap large trees, cars, debris, etc., to its breaking limit. The trapping function should be utilized more in the future designs of inland forests, if possible, on embankments.  相似文献   

20.
全球生态系统的状况与趋势   总被引：3，自引：0，他引：3  
简要介绍了千年生态系统评估（MA）项目状况与趋势工作组的报告《生态系统与人类福祉：现状与趋势》中的第3部分，即“对提供生态系统服务的各类系统的评估”。评估结果表明，在20世纪的后50年，全球生态系统的变化幅度和速度皆超过了人类历史上有记录的任何一个相等时间段的情况，目前人类活动实际上已经显著地改变了地球上的所有生态系统。这些变化主要表现在：① 大约1/4的地球陆地表层已经转变为垦殖系统，而且在1950年之后的30年中，转变为农田的土地面积比1700—1850年这150年间转变的总和还要多；②全球大多数的重要流域，由于水资源利用造成的栖息地丧失与破碎化，以及由于养分、沉积物、盐分及有毒物质造成的污染，已经显著地破坏了河流、湖泊和盐水沼泽等湿地生态系统的功能与生物多样性；③ 旱区系统存在着水资源匮乏、过度垦殖、过度放牧和过度砍伐树木等问题，生态状况尤其令人担忧；④ 栖息地的丧失与破碎化、过度开发、污染以及气候变化，已经对海滨系统造成了严重的生态威胁；⑤ 不可持续的农业开发模式，已经严重地破坏了热带森林生态系统的结构与功能。  相似文献   

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