黄河三角洲工程防护区海床侵蚀过程与不稳定性评估

近年来受入海水沙减少、海岸带高强度开发和海洋动力作用等的影响,黄河三角洲近岸海床侵蚀凸显。基于实测地形和波浪资料,研究了黄河三角洲工程防护区海床侵蚀过程及稳定性变化。工程防护区海床侵蚀主要分布在近岸10 km内,2007—2015年距岸8 km区域内表现强烈侵蚀,堤前海床较2000—2007年时段侵蚀量增大,海床侵蚀向岸加剧。随着现行河口沙嘴的淤积延伸和孤东浅水区的不断侵蚀,孤东南大堤外海逐渐形成了"近岸区深,远岸区浅"的反剖面形态。随着工程防护区近岸持续侵蚀,等深线不断向岸移动,堤前海床不稳定性逐渐加剧,2015年84.20%的堤前海床处于强或极强不稳定状态。本研究可为新形势下黄河三角洲综合治理提供科学依据。     

山东威海滨海沙滩侵蚀现状和原因分析

通过对威海市滨海沙滩的现场调查,综合分析了滨海沙滩侵蚀现状和侵蚀原因。威海市90%的滨海沙滩遭受侵蚀,沙滩资源遭到严重破坏,其中长度短小的沙滩和位置偏僻的未开发使用或者仅作生产使用的沙滩侵蚀情况较为严重。威海市的沙滩侵蚀主要表现在沙滩变窄、沙滩变陡、滩面物质粗化、侵蚀陡坎频现、老地层裸露和人工构筑物破坏等方面。沙滩侵蚀的原因可分为自然因素和人为因素两大类,自然因素包括:风暴潮、季节变化、海平面上升、构造下沉、气候变化和海岸地貌形态,人为因素包括:前滨采砂、海岸天然屏障破坏、河流输沙量减少和不合理的海岸工程。自然因素中,事件性风暴浪对滨海沙滩的侵蚀作用最为快速和显著。人为因素是造成滨海沙滩侵蚀的最主要因素,前滨采砂、河流输沙量减少和不合理的海岸工程会使沙滩在较短的时间内遭受侵蚀,而海岸天然屏障破坏则是人们比较容易忽视的环节。     

海平面上升对海岸侵蚀影响评估:平衡剖面模型（英文）

评估了海平面上升情景和共享社会经济发展路径下辽东湾砂质海岸潜在侵蚀状况及其社会经济影响。结果显示,2100年辽东湾海平面将上升20～43厘米。在所有海平面上升情景下土地损失均增加,2100年RCP8.5情景下土地损失最大达到32.1平方千米。受海岸侵蚀影响,沿海人口将被迫迁移,SSP3情景下人口增长较快且迁移人数最多,2100年SSP3/RCP8.5情景下将达到3.1万人。2050年后,不同情景下的迁移人口差别将增大,在RCP2.6和RCP4.5情景下人口迁移速率将逐渐减小。2100年,SSP5/RCP8.5情景下海岸侵蚀经济损失最大将达到80.5亿元,而在海岸侵蚀造成的经济损失中,土地损失比人口迁移损失小两个数量级。在所有情景下,海岸侵蚀经济损失占当地GDP的份额约为1.12‰～4.76‰,这值得当地管理部门关注,并采取减缓海岸侵蚀的措施,尤其是加强对旅游沙滩的保护。建议采取最优的海岸防护方案,重点对价值较高的沙滩进行养护,在海岸侵蚀影响较小的区域可不采取养护措施。     

中国海岸近期侵蚀问题

中国海岸侵蚀主要出现于废弃三角洲前缘地带和现代三角洲局部地区。其次出现在堆积性海岸阶地或沙坝区域。 河流沉积中心转移、流域来沙减少、河口水动力变异是废弃三角洲和现代三角洲侵蚀的重要条件;陆架供沙不足是海岸砂质堆积体蚀退的主要原因;较高能量的海浪、风暴和近岸水流作用是海岸侵蚀的主要动力因素;海平面上升对海岸蚀退有一定影响。 目前,中国海岸侵蚀仍在继续。今后,随着海岸带的开发建设,必须重视对海岸侵蚀的防护。     

深圳湾人造沙滩选址和修复方案

深圳湾经过近三十年的围填海活动,沿岸动力条件发生较大变化,如今自然状态下难以发育沙滩。从构建高品质游憩空间、防护海岸和提升旅游开发价值来看,沙滩是深圳湾急需的资源。为了加强人和海洋的联系、激发深圳湾的活力,建立城市自然缓冲区、化解极端风暴的威胁,以此达到防护海岸和满足居民休闲游赏需求的目的,本研究以近岸海洋要素的自然属性为主,海洋开发活动等社会属性为辅进行综合分析,并辅以数值模型进行验证,在深圳湾内选择适宜开展沙滩修复的海岸。沙滩修复选址时考虑了波浪、潮流、地形、地貌、沉积物等近岸海洋要素;数值模型包括潮流场模型、波浪模型和沙滩长期的平面演化模型。本研究案例对岸线动态变迁较大,自然状态难以发育沙滩的海岸的人造沙滩选址和设计方案提供示范与借鉴。     

江苏省海岸侵蚀现状遥感监测与防治对策

文章利用卫星遥感解译、潮汐数值模拟、GIS空间拓扑分析等技术手段,对水边线进行水位订正,推算出2019年度江苏沿海的遥感海岸线,对江苏省海岸侵蚀现状进行了遥感监测与评估。研究结果表明:2019年江苏省共有侵蚀岸线长58.55 km,占全省大陆海岸线的7.39%。废黄河三角洲侵蚀型海岸的侵蚀岸段平均年侵蚀后退 59.24 m,主要表现为盐养围堤的冲刷水毁;辐射沙洲北翼淤长型海岸的侵蚀岸段年平均侵蚀后退152.28 m,表现为潮间带上部坡度变缓,海岸线持续内移。全省海岸带侵蚀总面积为 7.244 8 hm2,强侵蚀岸段主要分布在南八滩闸北侧,新洋河口两侧以及斗龙港南侧区域。文章同时结合江苏海域动态监管工作经验,提出了5点海岸侵蚀灾害防治对策:①加强天-空-地一体化多手段联合监测,精确监控海岸侵蚀灾害发生范围与程度,了解海岸侵蚀强度与等级;②联合多平台海洋观测,深入开展致灾因素分析,了解海岸侵蚀灾害的发展与变化趋势,逐步完善灾害预警机制;③根据不同的海岸类型与海岸侵蚀特征,有效开展多策略的海岸防护整治,减少海岸侵蚀灾害损失;④加快海岸带保护修复,明确海岸带开发活动的适宜空间与适宜程度,优化海岸带空间布局;⑤强化海岸责任管理,明确监管职责。     

生态海岸防护工程研究进展与展望

海岸防护工程对防止海岸带侵蚀,维持生态系统完整性和多样性至关重要。传统硬质海堤较少考虑其对海岸带生态环境的影响。随着中国进入生态环境高质量发展新阶段,对海岸防护工程的生态效应方面提出了更高的要求。目前,对已建成的硬质海堤进行生态化改造,或在充分考虑自然条件和防护性能的基础上建设具有保护与维持海岸带生态环境的生态海岸防护工程已是大势所趋。生态海岸防护工程的宗旨是尽可能地维持当地海岸带的自然生态环境,同时通过削减波浪能量保护海岸带侵蚀。目前关于生态海岸防护工程主要集中在理论和理念方面,在具体的实施和建设环节,仍存在建设标准不完善、建设成本过高、缺乏系统持续的监测数据以及生态效应评估不足等问题。因此,后续应进一步完善我国生态海岸防护工程技术体系,加强生态海岸防护工程关键技术研发,建立持续的系统的环境生态监测体系,并对生态海岸防护工程生态效益进行持续关注和评价。     

福建海岸侵蚀风险评价研究

海岸侵蚀和淤积一直存在于海岸带系统内并塑造着现在的海岸线,近年来不当的人类活动以及全球气候变化加剧了海岸侵蚀,导致沿海土地流失,威胁人类生命财产安全。本文构建了海岸侵蚀风险评价理论体系,阐述了海岸侵蚀风险评价的方法,为海岸侵蚀风险管理提供有效指导。运用层析分析法确定评价指标权重;根据模糊集理论合成海岸侵蚀风险等级。以福建省海岸带为例,进行了海岸侵蚀风险评价,编绘了风险评价图,评价结果与客观情况比较吻合,验证了文中理论方法的适用性。本文构建的海岸侵蚀风险评价理论体系可以推广到其他区域,但应根据实际情况适当调整指标个数以及指标权重。     

山东半岛东部典型砂质海岸侵蚀特征及其影响因素

利用岸滩剖面高程监测、沉积物粒度变化和动力环境分析的方法,以海阳市沙滩侵蚀演化过程为例分析了山东半岛东部典型砂质海岸的侵蚀特征和影响因素。结果表明,海阳市沙滩整体以侵蚀为主,2018—2019年沙滩总侵蚀量为2.48×10⁴m³。其中,丁字嘴沙滩以侵蚀为主,但两侧受河口的影响呈现局部滩面稳定和后滨弱淤积的现象;潮里—庄上—羊角畔沙滩滩面侵蚀从西向东逐渐增强;万米沙滩中部侵蚀严重,两端相对较弱。表层沉积物由陆向海逐渐变细,但整体上呈现粗化的趋势。波浪和极端天气是控制沙滩侵蚀变化的重要动力因素,而坡度则是导致沙滩剖面形态变化和表层沉积物差异的重要因素之一。     

国际海岸带生态防护对我国生态海堤建设的启示

为充分发挥海堤的防灾减灾和生态服务功能,促进我国海岸带生态防护,文章概述国际海岸带生态防护的理念、案例、特点和效果,基于我国生态海堤建设研究和实践,提出启示和展望。研究结果表明:荷兰等国家通过生态缓冲和堤防后退等手段开展海岸带生态防护,在减缓海岸侵蚀的同时提升生态服务功能;我国相继开展生态海堤建设研究和实践,取得一定成效,但仍存在局限性,亟须借鉴先进经验,结合我国海岸带生态环境特点,针对新建海堤和已修建海堤,分别提高生态化水平;未来我国生态海堤建设将进一步完善理论体系、改进工程技术、建立调查数据库以及促进工程规范化和系统化。     

Integrating anthropogenic factors, geomorphological indicators and local knowledge in the analysis of coastal flooding and erosion hazards

The settlement and development of Québec’s maritime coastline has generally taken place without consideration for coastal dynamics and coastal hazards. Consequently, fighting coastal erosion has become a necessity. Until now, the construction of rigid walls and encroachments has been the preferred approach to the problem. In the Chaleur Bay region, coastal communities are particularly vulnerable to erosion and flooding because a number of residential, commercial and transportation infrastructures have been installed on beach terraces and sand spits. Recent storms, such as the storm of December 2, 2005, have made possible a better understanding of how these rigid defence structures amplify the effects of storm surges and waves. These structures drive the sand away from the coast, lowering beach levels and even causing beaches to vanish entirely from the areas situated in front of the defence structures. The end result is a weakening of the natural capacity of these coastal systems to absorb the energy of waves and a greater risk of coastal flooding. An integrated approach using local knowledge on the one hand, along with LIDAR surveys and a DGPS system on the other hand, have made possible to map the levels reached by flooding at the time of the storm. The results indicate that such levels vary greatly in spatial terms and that the difference between the levels actually reached and the water level measured by tide gauge can be as much as 2 m; a difference that is due to anthropogenic perturbations. This raises questions concerning the safety and the reference levels used for mapping coastal flooding risk. Taking into account knowledge of local communities, analysis of water levels, geomorphological indicators and aggravating anthropogenic factors, an approach and basic criteria are put forward with a view of establishing a reference level for the mapping of flood risk that can be used by community land-use planners.     

A simplified hindcast method for the estimation of extreme storm surge events in semi-enclosed basins

Human presence, coastal erosion, and tourism activities are increasing the attention to coastal flooding risk. To perform risk assessments, long time series of observed or hindcast wave parameters and tide levels are then necessary. In some cases, only a few years of observation are available, so that observed extreme data are not always representative and reliable. A hindcast system aimed to reconstruct long time series of total tide levels may be of great help to perform robust extreme events analysis and then to protect human life, activities as well as to counteract coastal erosion by means of risk assessments. This work aims to propose a simplified method to hindcast storm surge levels time series in semi-enclosed basins with low computational costs. The method is an extension of a previous work of some of the authors and consists of a mixed approach in which the estimation of storm surge obtained by using the theory of linear dynamic system is corrected by using a statistical method. Both steps are characterized by low computational costs. Nevertheless, the results may be considered reliable enough also in view of the simplicity of the approach. The proposed method has been applied to the Manfredonia case study, a small village located in the Southern Adriatic Italian coast and often prone to coastal flooding events. The comparison of extreme events estimated on the basis of hindcast levels time series is satisfactorily similar to those estimated on the basis of observed tide series.     

雷州市沿海风暴潮淹没危险性评估*

文章基于近岸海洋数值模式ADCIRC (a parallel advanced circulation model for oceanic, coastal and estuarine waters)和近海波浪数值模式SWAN (simulating waves nearshore), 建立雷州市高分辨率的风暴潮-海浪耦合漫滩数值模型, 并反演了对雷州市影响较为严重的1415号台风“海鸥”的风暴潮过程。经过对比分析得出, 波浪对雷州市沿海海域的风暴潮产生重要影响。然后以8007号台风路径为基础, 构造了7个不同等级共35组台风风暴潮案例, 计算分析出不同等级台风强度下雷州市风暴潮淹没范围及水深。900hPa等级下, 雷州市淹没面积达到463.2km²。文章还构造了60组可能最大风暴潮事件集, 计算得到雷州市可能最大台风风暴潮淹没范围及水深分布。在可能最大台风影响下, 大量海水将漫过海堤, 造成极其严重的淹没灾害, 雷州市总的淹没面积可达602.0km², 其中465.8km²的淹没面积达到了危险性等级 Ⅰ 级, 淹没水深大于3m。雷州市东岸的淹没灾害大于西岸。     

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.

     

Flood and coastal erosion risk management policy evolution in Northern Ireland: “Incremental or leapfrogging?”

Climate change poses a significant challenge for the future of Northern Ireland’s coast due to impacts that include, inter alia, mean sea level rise of between 13 cm and 74 cm by 2050. Whilst flooding is regarded as a major hazard in the United Kingdom (UK), to date Northern Ireland’s experiences of coastal flooding have been infrequent and less severe compared to those in England and Wales. Similarly, coastal erosion has historically been, and remains, only a minor concern in Northern Ireland. Partly as a result of this, Government administrative arrangements for Flood and Coastal Erosion Risk Management (FCERM) in Northern Ireland operate in the absence of any statutory provision for coastal erosion, as well as without formal or strategic shoreline management planning and any integrated flood and coastal erosion risk management policy. This paper provides a commentary on Northern Ireland’s approach to FCERM, comparing this with its UK counterparts, highlighting both congruence and divergence in policy evolution and development. It is noted that the recent EU Floods Directive has been a significant catalyst and that the current institutional landscape for FCERM is in flux.     

Quantifying the storm erosion hazard for coastal planning

The quantity of coastline retreat resulting from storm erosion is one of the most important phenomena that needs to be accurately quantified to facilitate effective coastal management strategies. Historically, the volume of storm erosion (and coastline retreat) accommodated for coastal planning decisions has been directly linked to the storm (usually defined by considering wave height and duration only) with a certain pre-defined return period, known as a Synthetic Design Storm (SDS) (e.g. 1 in 100 year storm). The SDS method of estimating storm erosion volumes for coastal planning thus assumes that, for example, the 1 in 100 year storm event also results in a 1 in 100 year erosion event. This communication discusses the physical reality of this assumption and demonstrates the improved performance of a new method, based on Joint Probability Distributions (JPD) for estimating storm erosion volumes proposed by Callaghan et al. [Callaghan, D.P., Nielsen, P., Short, A.D. and Ranasinghe, R., 2008. Statistical simulation of wave climate and extreme beach erosion. Coastal Engineering, 55(5): 375–390] using one of the world's longest beach profile surveys from Sydney, Australia.     

辽宁省海岸的蚀淤等级与分布

为了查清辽宁省海岸的蚀淤等级和分布,从1990年和2007年遥感图像中提取了17年的岸线变化信息,结合辽宁省908专项海岸带海岸侵蚀特征的调查资料,对全省海岸蚀淤情况进行了等级划分,并对其形成原因进行了分析与评价。结果表明,砂质海岸侵蚀较重的区域主要分布在绥中和熊岳一带,黄海岸段的砂质海岸基本稳定,基岩海岸侵蚀较重的区域主要分布在老铁山一带,粉沙淤泥质海岸侵蚀较重的区域分布在庄河一带。摸清辽宁省海岸蚀淤等级分布,对海岸整治与修复、海岸侵蚀灾害的防治与防护以及海岸带管理具有一定的指导意义。     

闽台海岸带生境质量时空演变及其影响因素

快速城镇化、工业化背景下对海岸带生境质量进行评估,揭示影响生境变化的关键驱动因子,对于海岸带生态可持续发展具有重要意义。本研究以福建东海岸和台湾西海岸（以下合称闽台海岸带）为研究对象,借助1990年、2000年、2010年、2020年的土地利用以及社会经济数据,运用InVEST模型及地理探测器分析土地利用变化下生境质量的时空演变特征及其影响因素,为城市生态空间优化提供可靠的理论依据。结果表明：（1）1990—2020年两岸土地利用变化以建设用地的增长及耕地的减少为主要特征。建设用地2000—2010年面积增长最多,年均增长5.66%。耕地作为建设用地面积最大转入来源,面积共减少1781?km2,年均减少2.55%。土地变化福建东海岸大于台湾西海岸。（2）1990—2020年闽台海岸带生境质量均值为0.82,总体生态质量良好,但呈下降趋势。2000—2010年两岸低等级生境面积增长最快,2010年后增长速度趋缓。生态用地向非生态用地的转移对生境退化的贡献率超过70%。（3）夜间灯光指数、人口密度、GDP、高程、坡度为影响生境质量变化的主要因素,30年间主导因素由地形因素变为社会经济因素。研究为闽台沿海地区陆海土地资源管理提供科学依据,对区域协同发展具有重要意义。     

福建沿海浪潮耦合漫堤风险评估:以台风天兔为例

漫堤是天文潮、风暴潮与海浪等物理要素作用于海堤后海水翻越海堤的物理过程。本文利用天文潮-风暴潮-台风浪耦合模式(ADCIRC+SWAN)、基于非结构三角形网格和高分辨率地理数据(海堤位置和高程、岸线和水深等)构建福建沿海精细化漫堤风险等级评估系统。该系统在近岸网格分辨率最高达50m,可精确刻画福建沿海复杂地形。利用模拟的水位与海浪参数,采用波浪爬高公式计算得到各海堤堤前波浪爬高。按照总水位与波浪爬高之和与海堤高程的对比,将漫堤风险分为五个等级。对2013年的超强台风天兔过程进行后报检验。结果显示,该系统计算的漫堤情况与灾后调查的漫堤实况基本一致,结果准确,说明本研究中采用的漫堤风险评估标准和方法是可行的。在此基础上,设计了4种不同的台风强度等级,对福建沿海206条海堤进行了漫堤风险等级评估,探究台风强度对漫堤风险的影响。结果表明:波浪爬高对漫堤风险的影响高于单纯的风暴潮增水;风暴潮增水随台风强度的增强增量较小,对于漫堤的风险影响较小;福建沿海波浪爬高普遍较高,随着台风强度的增强,波浪爬高会显著增加漫堤的风险等级,且应重视台风浪对海堤造成的冲击所导致的溃堤灾害。本研究可为沿海防灾减灾提供...     

Assessment and management of coastal multi-hazard vulnerability along the Cuddalore-Villupuram, east coast of India using geospatial techniques

The current study area is coastal zone of Cuddalore, Pondicherry and Villupuram districts of the Tamil Nadu along the southeast coast of India. This area is experiencing threat from many disasters such as storm, cyclone, flood, tsunami and erosion. This was one of the worst affected area during 2004 Indian Ocean tsunami and during 2008 Nisha cyclone. The multi-hazard vulnerability maps prepared here are a blended and combined overlay of multiple hazards those affecting the coastal zone. The present study aims to develop a methodology for coastal multi-hazard vulnerability assessment. This study was carried out using parameters probability of maximum storm surge height during the return period (mean recurrence interval), future sea level rise, coastal erosion and high resolution coastal topography with the aid of the Remote Sensing and GIS tools. The assessment results were threatening 3.46 million inhabitants from 129 villages covering a coastal area 360 km² under the multi-hazard zone. In general river systems act as the flooding corridors which carrying larger and longer hinterland inundation. Multi-hazard Vulnerability maps were further reproduced as risk maps with the land use information. These risk caused due to multi-hazards were assessed up to building levels. The decision-making tools presented here can aid as critical information during a disaster for the evacuation process and to evolve a management strategy. These Multi-hazard vulnerability maps can also be used as a tool in planning a new facility and for insurance purpose.