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Beach change over individual wave cycles on sand and gravel beaches

沙滩和砾石海滩上各个波浪周期的海滩变化

基本信息

批准号：
NE/F009275/1
负责人：
Gerhard Masselink
金额：
$ 9.71万
依托单位：
Plymouth University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2008
资助国家：
英国
起止时间：
2008 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FF009275%2F1
关键词：
Beach change over individual wave

项目摘要

Pressures on the coastal zone are increasing due to global warming, with sea-level expected to rise by 0.5 m over the next century. Rising sea levels combined with increased storminess is expected to enhance coastal erosion. In England alone, the management of flood and coastal erosion risk costs £600 million per year, a figure that is expected to increase significantly over the next decades. Natural beaches are widely thought of as the best form of protection against erosion as they form a natural buffer against incoming wave energy, hence the popularity of beach nourishment (placing extra sand on the beach) as a management measure. It has long been known that beaches build-up (accrete) in calm wave conditions and are cut back (erode) in storm conditions. Whilst this cycle has been observed, it has not been accurately measured, largely due a lack of suitable instruments that can record the erosion and accretion at the same time as the waves and currents that cause them. As a result, our ability to predict beach erosion and accretion remains poor, making it difficult for coastal managers to plan future coastal land use. This project will use an exciting new measurement technique developed in collaboration between researchers at the University of Plymouth (UK) and the University of New South Wales (Australia) in 2005. The new instruments measure the level of the beach a few times each second, so that after each wave passes up the beach, we can see whether the level of the beach has gone up (accretion) or down (erosion). By installing a large number of these instruments on the beach, we will be able to see how small changes in beach level after each wave add together to cause beach accretion and erosion over hours, days and weeks. Such measurements have never before been made. We will collect data during two four-week field campaigns on two contrasting beaches. The first experiment will take place in March 2008 on Truc Vert, a sandy beach on the Atlantic coast of France near Bordeaux. This field campaign is part of a much larger multi-national beach experiment and provides a one-off opportunity for UK researchers to collect their new measurements of beach change, coincident with a whole range of other measurements made by other leading research groups. The second field campaign will take place in May 2008 on Slapton Sands, a gravel beach on the south coast of Devon in the UK. Slapton Sands is one of only 20 beaches in the world that are being permanently monitored using video cameras and wave buoys, providing very useful background information for our measurements. Previous research conducted by us has shown that both Truc Vert and Slapton Sands build up and erode by 1 m with changes in wave conditions, making them ideal sites for this study. Both campaigns will continue day and night for 4 weeks in order to capture a wide range of wave conditions. Analysis of the data will enable us to understand how wave, current and sand transport processes combine to cause beach erosion and accretion. Using these wave, current and sand transport measurements, together with the new measurements of beach change, mathematical equations will be developed that can then be used to predict beach erosion and accretion. This will help improve the management of our coasts in the future. This is a 2-year project between researchers at the University of Plymouth (UK) and a Visiting Researcher from the University of New South Wales (Australia), and also involving researchers from the University of Bordeaux (France). Our new measurements of beach change on the two contrasting beaches will ensure significant advances are made in our ability to predict beach erosion and accretion. The results will be published in academic journals and presented to experts around the world at a major international conference in Japan.

由于全球变暖，沿海地区的压力正在增加，预计下个世纪海平面将上升0.5米。海平面上升加上暴风雨加剧，预计将加剧海岸侵蚀。仅在英格兰，洪水和海岸侵蚀风险的管理每年就耗资6亿GB，预计这一数字在未来几十年将大幅增加。天然海滩被广泛认为是防止侵蚀的最佳形式，因为它们形成了对到来的海浪能量的天然缓冲，因此海滩滋养(在海滩上放置额外的沙子)作为一种管理措施很受欢迎。人们早就知道，海滩在平静的海浪条件下堆积(共生)，在暴风雨条件下被削减(侵蚀)。虽然观察到了这一周期，但没有准确测量，这主要是因为缺乏适当的仪器来记录侵蚀和淤积，同时记录引起侵蚀和淤积的波浪和洋流。因此，我们预测海滩侵蚀和淤积的能力仍然很差，这使得沿海管理者很难规划未来的沿海土地利用。该项目将使用2005年普利茅斯大学(英国)和新南威尔士大学(澳大利亚)的研究人员合作开发的一种令人兴奋的新测量技术。新的仪器每秒测量几次海滩的水位，这样每次海浪经过海滩后，我们就可以看到海滩的水位是上升(淤积)还是下降(侵蚀)。通过在海滩上安装大量这样的仪器，我们将能够看到每次海浪后海滩水位的微小变化如何叠加在一起，导致数小时、数天和数周的海滩淤积和侵蚀。以前从未进行过这样的测量。我们将在两个对比鲜明的海滩上进行为期四周的两次实地考察活动，收集数据。第一次实验将于2008年3月在法国波尔多附近大西洋海岸的特鲁克海滩上进行。这项实地考察活动是规模更大的跨国海滩实验的一部分，为英国研究人员提供了一个一次性的机会来收集他们新的海滩变化测量数据，这与其他领先研究小组的一系列其他测量数据相吻合。第二次实地活动将于2008年5月在英国德文郡南海岸的碎石海滩斯莱普顿沙滩上进行。斯莱普顿金沙是世界上仅有的20个使用摄像机和波浪浮标进行长期监测的海滩之一，为我们的测量提供了非常有用的背景信息。我们之前进行的研究表明，随着波浪条件的变化，Truc Vert和Slip ton Sands都会堆积和侵蚀1米，这使它们成为本研究的理想地点。这两项活动将持续4周，日夜不停地捕捉各种海浪情况。对数据的分析将使我们能够了解波浪、水流和沙子输送过程是如何结合在一起导致海滩侵蚀和淤积的。利用这些波浪、水流和泥沙输运测量，以及海滩变化的新测量，将建立数学方程，然后可用于预测海滩侵蚀和淤积。这将有助于改善我们未来对海岸的管理。这是一个为期两年的项目，由英国普利茅斯大学的研究人员和澳大利亚新南威尔士大学的访问研究员共同完成，波尔多大学(法国)的研究人员也参与其中。我们对这两个对比海滩的海滩变化进行的新测量将确保我们在预测海滩侵蚀和淤积方面取得重大进展。研究结果将发表在学术期刊上，并在日本举行的一次重要国际会议上向世界各地的专家展示。