The Sea-Defence Value of Salt Marshes: Field Evidence From North Norfolk

Approaches to coastal management have focused increasingly on 'soft'engineering methods such as beach/foreshore recharge or the managed realignment of coastal defences. In this context, the creation/maintenance of salt marshes is often seen as being of ecological and flood-defence importance. However, until recently, no field data of wave attenuation over Northern European salt marshes had been available; therefore the debate on the sea-defence value of salt marshes has remained highly speculative. This paper (a) reviews results from a field and numerical modelling study at Stiffkey, north Norfolk, (b) presents a scientifically based argument for the evaluation of salt marshes as part of sea-defence schemes, and (c) discusses the relationship between hydrodynamic parameters, salt-marsh surface characteristics, and possible management implications and engineering guidelines.     

Night and day at the beach: Relating social life to location and infrastructure in a Brazilian city

Brazilian city beaches are public spaces favoring citizens well-being. Urban studies relate built form and infrastructure with urban vitality and coastal studies underline uses as important for beach management, yet few researches relate form and infrastructure with beach uses. Understanding daily life as essential for public spaces and that spatial form relates with uses, this paper assesses time-based relationships between built and natural physical attributes and social life on the beaches of João Pessoa, a coastal city in North-east Brazil. Physical attributes are investigated at city scale - beach type, street network centrality and topography - and seafront scale - land uses, public/private interfaces, public infrastructure, beach sections and water quality. Beach social life was surveyed online, enquiring peoples' beach choice, visiting time and place, activities and evaluation. Infrastructure and street network follow topography and help configure shore and promenade for different landscapes. More central beaches have diverse land uses, well-equipped promenades and lighting and were popular night and day, while less central beaches had less infrastructure and were visited only by day. Findings highlight how physical attributes facilitate uses and, together with peoples’ evaluation, can inform urban beach design and planning.     

南海海滩岩的细观结构及其基本物理力学性质研究

 海滩岩为热带、亚热带地区砂质海滩上由碳酸钙胶结潮间带沉积物形成的一种海滩相沉积岩,为海滩相常温常压胶结成因的岩石,其广泛分布于我国南海的珊瑚岛礁及沿岸地带,对其岩土工程性质的研究必将对我国海洋权益的保护及国防建设有重大的理论意义。本文首次对取自南海不同岛礁及沿岸的海滩岩样,采用宏微观相结合的研究手段,力图找到控制海滩岩强度的主要参数,为进一步开展海滩岩的深入研究提供理论支持。研究表明,海滩岩具有低密度、高孔隙率,因而具有较大的渗透性;其胶结度介于弱胶结至中等胶结之间,风干状态下的单轴抗压强度为2.02～19.39 MPa,饱和会使海滩岩的强度有不同程度的降低,软化系数(Kd)达到0.45～0.96,一般情况下,胶结度越低,软化系数越小。海滩岩的抗拉强度介于0.64～2.52 MPa间,风干状态下抗压强度与抗拉强度之比为3.08～9.14,该值小于常规陆源岩石8～12的统计值,该值可以作为不同成岩方式表征参数。物理与力学参数间的相关关系分析表明,密度和胶结度是控制海滩岩强度的主要参数,单轴抗压强度随着密度及胶结度的增加而明显升高;孔隙率及颗粒粒径对单轴抗压强度的影响不明显。     

Quantitative assessment of the shoreline protection performance of geotextile sandbags at an in-situ coastal experimental station

The coast of China is periodically impacted by tropical cyclones and storm surges, and has experienced significant coastal erosion problems. Traditional “hard engineering” coastal protection measures used to protect Chinese sandy coasts from storm erosion are found to be expensive and less environmental and even make sandy beach disappearing. In this study, geotextile system as a more flexible material was developed and qualitatively compared with the traditional coastal protection measures. An in-situ permanent revetment was applied with durable geotextile sandbags on the coast of Chudao in China from October 2018 to October 2020, and it was designed for three different testing segments to optimize the stability and construction cost of geotextile sandbags. The field surveys were carried out to collect the in-situ data on beach profiles, wave dynamics, material durability, and sandbag revetment stability. In analyzing the two-year field data collected, it is found that the testing segment-2 wrapped with sheet of plastic geogrids is the most effective of the three testing segments in terms of their coat, structural stability and material durability, and that both the slope of the seabed and the design thickness of geotextile sandbag are the dominate factors responsible for the failure of sandbag structures.     

Beach protection and restoration Part II: a perspective of “soft” methods

In Part I (Vide previous issue) the authors underscored the world‐wide character of coastal erosion and particularly the shrinking of beaches. If nature is the causal agent, man clearly enhances the process. To counter the steady encroachment of the sea upon the land, several protective devices have been placed along the shores. Some of these were even conceived as means to bring about sand accretion in specific sites.

The results have been overall disappointing, or of local value only. In this paper beach protection and beach restoration methods that call upon the natural processes are examined. The “soft” approach to the problem includes implanting artificial reefs, placing vegetation, or fences, on dune or beach, and especially artificial beach nourishment.     

Some factors affecting coastal landscape aesthetic quality assessment

Seventy beaches in Wales, UK, were investigated with regard to quality of beach scenery using video panoramas. Scenic beauty was judged by three groups: coastal managers/academics; students in environmental sciences; and technical staff with no environmental training. Cloud cover at time of filming had a significant effect on scoring so a correction was applied for further data analysis. A strong preference was observed for undeveloped beaches over those where anthropogenic structures were prominent (p = 0.00), and for beaches with high relative relief. Beach commercialization level had an independent effect only on scores from the student group (p = 0.02). Results suggested that coastal managers/academics may assess beach landscape quality according to different criteria to those applied by people with no environmental training. Extreme scores did not seem to be well predicted by analysis of quantifiable landscape components and scores from the untrained judging group were also less predictable. The findings could contribute to coastal aesthetic resource management by demonstrating the feasibility of quantitatively assessing beach scenic quality for a large number of beaches. Identification, albeit tentative, of landscape parameters important in scenic quality assessment by various stakeholder groups could also contribute to the coastal management/planning process.     

The effect of sea level rise on beach morphology of caspian sea coast

Study of beach morphology has been one of the most important issues in coastal engineering research projects. Because of the existence of two important coastal areas located in the north and south parts of the Iran, in the present study an analysis of the coastal zone behaviour is made. Bed level elevations are measured and compared with the theoretical equilibrium profile. It is shown that the behaviour of the coastal zone in the region is consistent with the Dean (1991) equilibrium profile. In the next stage, following extensive investigations, the bed level changes due to arise in sea level at different locations in the surf zone are estimated. The mechanism of beach re-treatment due to a rise in sea level is considered based on the simplified model of Dean (1991) in which the mass balance of the sediments is taken into account. Comparison of the equilibrium profiles for different cases of sea level rise, clearly shows that because of the sediment transport induced by the fluctuation of the water level, the beach profile in the surf zone changes accordingly resulting in an erosion in the inner region of the surf zone and an accumulation of sediments towards the offshore.     

海滨旅游空间的符号学与文化研究

在比较了自然科学(特别是旅游地理学)和文化研究两个不同视角所建构的2种不同的海滨旅游空问模式后,指出从文化研究角度探讨海滨旅游空间是传统旅游地理学研究视角的重要补充.接着在社会建构理论与符号学的分析框架下,讨论了海滨从"自然空间"转化为"旅游空间"的历史过程,并以深圳海滨为例,分析指出海滨旅游空间的社会实践和社会建构,本质上是一个符号意指过程,包括神圣化和去神圣化的过程,在这个过程中,形成了海滨的"边缘性"、"过渡性"、"浪漫性"、"女性化"、"感性"、"异国情调"和"殖民性"等多重符号意象.     

现代新型芦苇屋面施工关键技术

天然芦苇质地坚硬,细且笔直,具有自重轻,韧性、防水性、隔热性良好,易取材及人文气息浓厚等特点.芦苇屋面是指以精选滩涂地生长的天然芦苇为材料建造的屋面.结合工程实践,总结了芦苇屋面的工艺流程及质量控制要点,可为类似的芦苇屋面施工提供借鉴.     

A perspective of material management practices in a fast developing economy: the case of Malaysia

Many management-related problems exist amongst local contractors in developing countries. Problems vary in nature and intensity but are usually associated with inefficient management of construction resources including materials, labour, plant and subcontractors. This paper deals with material management practices in the construction industry in Malaysia. A questionnaire survey and interviews were conducted with local practising public works contractors to examine the management of materials and to identify the nature of problems associated with material management. Problems identified included delay in the delivery of materials, the lack of use of advanced planning techniques, material variances and computers. There is a need for an improved material management approach by contractors in a developing country.     

Coastal landslide activity: a probabilistic simulation model

A process-based simulation model of coastal landslide activity is described which uses Monte Carlo simulation to build up probabilistic predictions of cliff recession. The model, CLIFFPLAN, represents the principal nearshore, beach and landsliding processes that are instrumental in coastal cliff recession. Its potential is demonstrated by application to an eroding coastal cliff site on the east coast of the UK. This type of process-based simulation model could be used to make probabilistic predictions of cliff response to proposed engineering schemes, such as cliff toe protection or beach nourishment, and to model the consequences of potential climate changes such as sea level rise or changing hydrological regimes. Electronic Publication     

Relationships between landforms,soils and vegetation in the River Plate coastal plain,Argentina

The River Plate coastal plain is a 160‐km‐long, 3–10‐km‐wide strip, located to <5 m a.s.l. on the right bank of the estuary. It is formed by sediments and landforms generated by the littoral transport and marine ingressions and regressions during the Holocene. The coastal plain faces heavy pressures from Buenos Aires Metropolitan Area, with about 13 million inhabitants, industrial, mining and rural activities. Here, we analyse the relations existing between landforms, soils and vegetation. Despite the anthropogenic influence, the natural landscape is more or less preserved in some areas, such as patches of the southernmost gallery forest in the world in natural levees, the xerophytic forests located in well‐drained soils of beach ridges and other units such as Inland and Coastal Mudflats with wetland soils and vegetation, Tidal Flats with contrasting soils and plant communities among others.     

Grouted and concreted soils: residue mapping of foundation techniques in Flanders,Belgium

Sand is one of the main raw materials used in infrastructure and road construction. While it is a common natural raw material worldwide, the locations where it can be found are not evenly distributed. Because Flanders is highly dependent on imported sand, there is a need to find alternatives. One alternative might be found in the residues from foundation techniques like grout, soil mixed with bentonite, and cemented soils. This paper reports an attempt to determine the annual amount of residues from these foundation techniques available on the Flemish market, by use of a market study. This study estimated that the annual amount of grouted soils and cemented soil remainders is more than 40% of the annual amount of natural sands dredged from the Belgian Continental Shelf. Preliminary tests show that grout and cemented soil remainders could be a valuable replacement for natural sand currently used in low grade applications like sub foundations and stabilized sands.     

星海湾人工海滨浴场的规划设计研究

对我国第一个人工海滨浴场规划设计中所遇到的关键问题, 进行了具有可操作性的研究。在研究中, 海滩物质采用一次充填, 用建筑物固定使之不流失的办法, 将陆域填筑的河西区南部岸线一分为三, 修建成为互不关联的三个海滩, 每个海滩分别用T形防波堤、L形防波堤以及潜堤等建筑物加以固定。研究的重点是海滩岸线平面形状、海滩剖面形状和固滩建筑物的布置。另一方面, 景观设计按多种要素进行设计, 考虑了提供多功能、多层次的开放游憩空间。该规划设计创立了通过海岸环境整治和景观生态设计, 形成环境、景观与城市相和谐的城市经营与开发模式, 对于我国港口及海岸工程建设具有较大的示范意义。     

浅谈建筑空间的气候适宜性设计

建筑是人工创造的物质空间,不仅要满足人们居住生活的基本需求,同时又要满足人们精神世界的某种需要.近年来,随着物质生活的不断提高,人们对视觉审美的需求愈加提高,而逐渐忽略建筑本体空问设计受自然条件的约束,尤其是自然气候要素的约束.基于以上,探讨了建筑空间设计与气候因素的关系,着重讨论了传统建筑的空间设计的"气候性"以及现代建筑中的几个建筑实例,以期对现代建筑空间的绿色设计有所启发.     

Employment of metamaterial cloaks to enhance the resolution of near-field scanning optical microscopy systems based on aperture tips

In this paper, we numerically demonstrate that plasmonic covers designed through the scattering cancellation approach can be successfully used to enhance the performance of near-field scanning optical microscopy (NSOM) systems based on the employment of aperture tip probes. The material used to partially cover the tip exhibits a near-zero value of the real part of the permittivity function at the working frequency and is designed in such a way to dramatically reduce the undesired electromagnetic coupling between the sample to be imaged and the metallic coating of the aperture tip. We show that minimizing such an unwanted interaction may lead to enhance the maximum achievable resolution of the NSOM system. The approach proposed is numerically tested at optical frequencies through a proper set of full-wave simulations, taking into account material losses and frequency dispersion. The proposed results represent a proof-of-concept and can be scaled at lower frequencies (infra-red and THz), where fabrication issues are more relaxed and possible implementation can be made practical using alternating plasmonic/non-plasmonic multi-layers or even some natural materials.     

粉煤灰坝模型试验研究

以湖南省耒阳电厂粉煤灰坝的加高加固工程为研究背景,采用大型液压伺服式振动台作为试验手段,分别对高程为170,180,230 m的灰坝模型进行了动力特性试验研究,并进行了计算验证。同时,对采用3种不同灰渣拌合料加高的180 m高程灰坝模型进行了动力特性评价并认为其对灰坝的整体动力特性没有太大的影响。试验结果表明,灰坝的自振频率是随着激振加速度的增大和坝体的加高而降低的;坝顶加速度放大倍率也是随激振加速度的增大而降低的;两者在有干滩工况下普遍大于无干滩工况。     

五种软基加固处理方法在工程中的应用分析

通过五种基本软基加固处理方法在某工程地坪施工段地基处理中的应用,详细介绍了排水板＋超载预压、真空联合堆载预压、CFG桩、预应力薄壁管桩、湿喷桩等五种不同地基处理方法的工艺要求及施工要点,并就其在该工程中对地基加固处理的效果从沉降量、施工工期、施工工艺及造价等方面作出分析对比,最后综合评价得出不同处理方法的优势及缺陷,为实际施工中的软基加固提供参考。     

Coastal Wave Modelling

C oastal engineering works are designed to serve two main purposes. These are the prevention of flooding of land adjacent to the shoreline, and the protection of a stretch of coast against erosion. The design of a scheme to achieve either of these aims will require information on the wave conditions which are likely to occur at a coastal site. This paper describes some of the methods which are available to predict waves at a coastal site, and summarizes some of the techniques which may be used to aid the design of coastal works.     

Development of cork–gypsum composites for building applications

This paper presents an experimental analysis on a new composite material, cork–gypsum composite. It is shown that cork and plaster are mutually compatible and that a lot of new building materials can be made by mixing those materials in different volume fractions. Mechanical properties of the cork–gypsum composite have been measured. The acoustic absorption coefficient and thermal conductivity of this new composite have also been experimentally obtained and those values are reported for design purposes. Concerning the acoustical insulation characteristics, this composite is not a sound-absorbing material but a reflecting one, and it needs some kind of perforations to behave as an absorbing construction material for sound and noise. The thermal insulation properties are quite good as a result of the thermal conductivity tests. This new composite material is suggested for use in building applications as partitions.