Contrasting biogeomorphic processes affecting salt‐marsh development of the Mokbaai,Texel, The Netherlands          下载免费PDF全文

Martin J. Baptist  Alma V. de Groot  Willem E. van Duin 《地球表面变化过程与地形》2016,41(9):1241-1249

The growth and decline of salt marshes may be the result of various interacting biogeomorphic processes and external factors. We present a case study of the Mokbaai on the Wadden island of Texel, where we assess the relative importance and the interaction between the biogeomorphic processes and various disturbances. We analysed changes in vegetation composition in the salt marsh and sedimentation–erosion patterns of the adjoining intertidal flat over a 30‐year period. Vegetation underwent regression in the lower parts of the marsh, i.e. the low marsh zone changed into pioneer zone. Comparing elevation measurements from 2013 and 1983 showed that the adjoining intertidal flats eroded 15–25 cm. Maintenance dredging of a nearby harbour might negatively impact the sediment balance indicating that the regression of the lower parts of the salt marsh is caused by a lack of sediment. Simultaneously, a change in the local hydrology led to vegetation succession into high and brackish salt marsh, increased organic sediment production and consequently cliff formation. The results from this case study show that, even in a relatively small salt marsh, changes in external factors may set in motion a series of biogeomorphic processes and feedbacks, leading to locally contrasting trends in spatiotemporal development. © 2016 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd.  相似文献   

软式扫浅在港池疏浚工程的应用     

陈建平 《地理空间信息》2012,10(4):155-156

针对码头港池疏浚工程中浅点施工的难点,利用扫海测量进行港池检测,及时发现施工中留下的浅点。分析了GPS定位和信标系统在疏浚工程中的缺陷以及各种类型浅点的特点;介绍了软式扫浅的基本原理、构架和优势;阐述了用软式扫床法对分散型浅点进行扫浅的案例;解决了疏浚工程中清理浅点和航行障碍物的问题,保证了船舶航行及停靠的安全。  相似文献   

The impact of the Habitats Directive on European port operations and management   总被引：4，自引：0，他引：4  

Timothy Andrew Stojanovic  Hugh D. Ormerod Smith  Christopher F. Wooldridge 《GeoJournal》2006,65(3):165-176

Thirteen years since the EU Habitats Directive (1992/43/EEC) became a binding legal agreement, this paper considers the implementation of this important European environmental legislation as it applies to the coastal activities of seaports and harbours. The paper examines the relationship between environmental legislation and ports policy, and seeks to provide a comprehensive assessment of the policy and science that has been developed in relation to protected areas and port management. The paper reports the results of a survey of European port professionals, and their perception of the successes and challenges of the management regimes that have been established, as well as their opinions on how these have influenced the management within ports. The paper also provides a detailed examination of the scientific and technical developments with particular regard to dredging and habitat management in European ports. Key research gaps are identified, including: practical approaches to licensing procedures; lack of baseline information, especially with regard to in-combination effects; the efficacy of techniques for mitigating the impacts of dredging; and greater understanding on how more resilient models for collaborative action can be developed. The paper will be of use to environmental planners, scientists, regulators, conservationists, and port managers, as they consider how to apply science and management to the sustainable development and environmental protection of coastal areas.  相似文献   

基坑围护结构渗漏的堵漏技术     

蔡文盛 《化工矿产地质》2007,29(4):249-254

将基坑围护结构渗漏类型按照基坑渗漏深度位置划分为:开挖面以上渗漏(俗称"明漏")和开挖面以下渗漏(俗称"暗漏")两种;根据围护结构所使用的材料划分为:钢筋混凝土缝隙渗漏和水泥土缝隙渗漏两种。采用疏堵结合,先疏后堵的堵漏技巧,针对不同情况,以瞬凝混凝土、膨胀及单管双液注浆三种简易有效的堵漏措施,效果良好。  相似文献   

广利河口航道整治研究     

饶永红  陈兆林  孙国峰  杨洪旗 《海洋工程》2007,25(1):120-126

广利河口拦门沙航道水深较浅,用双导堤结合航道疏浚进行整治。通过潮流定床模型试验对航道走向、导堤间距、高程、水流流态和堤头布置等进行了方案优化,同时采用局部动床定性试验进行了验证。推荐方案沿程流速、流态分布合理,基本能维持航道水深并满足设计船型的航行条件,可供类似河口治理参考。  相似文献   

大力开发整治射阳河之浅见     

杜渺  董庆松 《海岸工程》1996,15(2):19-24

分析苏北里下河地区排水入海的最大干河－－射阳河在本流域中的地位和作用，目前河道淤积，工程老化和水污染严重等现状，以及射阳河蕴藏着的河海联运，水源充足，自然和人文景观众多潜在优势；阐述了整治和综合开发利用射阳河的重要性和迫切性；提出了整治和开发利用的３条总体原则，大体思路及保证顺利实施的关键措施。  相似文献   

A novel shear vane used to determine the evolution of hydraulic dredge tracks in sub-tidal marine sediments     

C. Hauton  D. M. Paterson 《Estuarine, Coastal and Shelf Science》2003,57(5-6):1151-1158

A novel shear vane is described which can be used to record the shear strength of discrete depth horizons of a variety of marine sediment types in situ. This vane, or modifications of it, has great potential in allowing measurement of in situ shear strength without requiring any samples to be removed from the sea bed, a process which can often destroy the fine structure of the sediment. The vane was used to monitor the change in sediment shear strength caused by a hydraulic dredge, which was used to fish razor clams (Ensis arcuatus) in a sheltered bay within the Clyde Sea area, Scotland. Data collected using this apparatus provided valuable and immediate information on the stratification of the sea bed post-dredging and allowed the evolution of the dredge track to be regularly monitored by divers over a period of 100 d.  相似文献   

挡潮闸下港道清淤机具的改进及应用     

许德智  陆体成等 《海洋工程》2001,19(2):74-78

我国许多挡潮闸，地睛淤泥质海岸，闸下港道淤积十分严重。为了清除闸下港道淤积，提高挡潮闸的排涝能力，对耙具作了改进，经历了单面齿耙、双面齿耙、掺气耙和改进型掺气耙四个发展阶段，本文介绍清淤耙的发展过程，并对各种耙具进行了对比。拖耙清淤机具具有效率高、费用低的特点，每立方米的清淤成本仅为常规挖泥船的三分之一左右。  相似文献   

南沙岛礁区中西部海底岩石拖网和发现早第三纪半深海沉积的地质意义   总被引：2，自引：0，他引：2  

周蒂  施小斌  陈汉宗  钟石兰 《热带海洋学报》2002,21(2):32-42

在南沙岛礁区中西部实施海底岩石拖网,有3个站获得海底岩石样品。其中在巽它陆架东北缘水深200多米的NS99－17站见深灰色淤泥中有大量铁褐色含泥钙质结核,说明该区（可能在末次冰期时）处于滨海或海滩氧化环境形成结核,之后海平面上升了至少150m。在南威岛西北方康泰滩的NS99－57站1360m水深的海底获强溶蚀的白垩多孔灰岩,含底栖有孔虫化石,指示康泰滩是从早－中中新世或更早开始生长的生物礁。在永暑礁东北约55km处的NS99－52站新命名了“东生海山”,其西北坡获含第四纪钙质超微化石的礁灰岩,以及由抱球虫类等生物碎屑和胶磷矿组成的钙质磷块岩和含磷生物屑灰岩滚石,指示半深海环境,其中的钙质超微化石大部分时代为中始新世－渐新世,以始新世可能较大,小部分属第四纪。这次海底岩石拖网为研究南沙岛礁区中部写信为和油气资源评价提供了重要的“硬证据”,尤其是发现早第三纪半深海相钙质磷块岩离南海西南次海盆很近,不但证实了南沙海域广布下第三系海相沉积的推断,而且为判断南海的张开时间提供了补充依据。  相似文献   

Morphological evolution of gravel and sand extraction pits, Tromper Wiek, Baltic Sea     

Adam Kubicki  Faustino Manso  Markus Diesing 《Estuarine, Coastal and Shelf Science》2007,71(3-4):647-656

The growing demand for marine mineral resources introduces anthropogenic impacts in the coastal zone, among others also through aggregate dredging. Pits created by anchor hopper dredging may affect local sediment budgets, local hydrodynamics and biological habitats. In this study we investigate the processes and time-scales of pits refilling at two extraction sites over 6 years following cessation of dredging. We focused on the evolution of a single pit at a gravel extraction site and the development of a group of three pits located at a sand extraction site. In the case of the gravel pit, a series of six sonograph and two multibeam surveys were evaluated. We observed a spatial expansion of the edge of the pit, decreasing availability of screened sand in the neighbourhood of the pit (a possible source of refilling), and a slowing down of the refilling process with time. At the sandy pit site a series of seven sonographs and two multibeam surveys were available. We observed a smoothing of the edges and larger mean refilling rates than in the gravel pit case. We conclude that the most effective method for monitoring of pit evolution is to make measurements every six months by simultaneously deploying sidescan sonar and multibeam devices.  相似文献