Composite Beaches - Can we protect our coastlines by mimicking nature?

复合海滩 - 我们可以通过模仿自然来保护我们的海岸线吗？

• 批准号: 2750093
• 金额: --
• 依托单位: University of Bath
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2750093
• 关键词: Composite; Beaches; protect; our; coastlines

Project BackgroundComposite beaches consist of a lower foreshore of sand and a naturally occurring permanent or semi- permanent backshore ridge of cobbles, and are ubiquitous beach environments in the UK, USA and NZ. These beaches are known to be highly stable because they combine a dissipative sand slope and a reflective cobble berm, which represent the two most stable end members in the classification of beach morphodynamics. Furthermore, when a permanent cobble ridge exists it can play a significant natural coastal protection role, stabilising the upper beach and providing overtopping protection to the hinterland. As a result, constructed cobble berms (or dynamic revetments) designed to mimic composite beach cobble ridges are being trialled to provide coastal defence at vulnerable beaches on the US West Coast with some success. Despite the common occurrence of composite beaches and their value as a natural form of coastal defence they have received very little attention in academic literature with almost no composite beach- specific studies being undertaken to date. As a result, understanding of composite beach processes such as cross- and longshore cobble transport, wave runup and overtopping of cobble ridges and response to sea level rise is minimal.Project Aims and MethodsThis project aims to fill this identified research gap and undertake one of the first detailed studies into composite beach behaviour. This work will enhance understanding of this valuable beach type and gain insight which will enable the design nature-based coastal defence structures which mimic composite beach behaviour to provide sustainable and low-cost coastal protection. This will be achieved through the following activities:1. Analysis of existing historical topographic data to elucidate the medium to long-term variability of composite beaches and their resilience to extreme storms and storm sequences. This will include a global assessment of composite beach stability using satellite imagery via the new "CoastSat" satellite coastal monitoring tool.2. Analysis of data from the recently installed (June 2021) permanent Lidar station at Borth beach which provides beach profiles and wave runup data continuously at 1 Hz. This analysis will focus on storm erosion and post-storm response.3. Field experiments using a newly-developed, wave-by-wave cobble tracking methodology at 2 or more composite beaches in Wales and/or USA to better understand the short term variability of composite beach ridges and the mobilisation of individual cobbles.4. Test and potentially develop the existing state of the art XBeach-G coastal model to predict morphology changes on composite beaches. If successful, this will improve our ability to assess the vulnerability of composite beaches to increasing storminess and provide a tool for the design of dynamic revetment coastal protection structures.

项目背景复合海滩由较低的前滨沙和天然存在的永久或半永久的后滨卵石脊组成，在英国、美国和新西兰是普遍存在的海滩环境。这些海滩被认为是高度稳定的，因为它们结合了联合收割机耗散砂坡和反射卵石护堤，这代表了海滩形态动力学分类中最稳定的两个端员。此外，当存在永久性卵石脊时，它可以发挥重要的天然海岸保护作用，稳定上部海滩并为内陆提供漫顶保护。其结果是，建造鹅卵石护堤（或动态护岸），旨在模仿复合海滩鹅卵石山脊正在试验，以提供海岸防御脆弱的海滩在美国西海岸取得了一些成功。尽管复合海滩经常出现，而且它们作为一种天然形式的海岸防御具有价值，但它们在学术文献中很少受到关注，迄今为止几乎没有进行过专门针对复合海滩的研究。因此，了解复合海滩过程，如跨和沿岸卵石运输，波浪爬高和漫顶的卵石脊和海平面上升的反应是minimal.Project Aims and MethodsThis项目的目的是填补这一确定的研究空白，并进行第一个详细的研究到复合海滩的行为。这项工作将加强对这种宝贵的海滩类型的理解，并获得洞察力，这将使设计基于自然的海岸防御结构，模仿复合海滩的行为，以提供可持续的和低成本的海岸保护。这将通过以下活动实现：1.分析现有的历史地形数据，以阐明复合海滩的中长期变化及其对极端风暴和风暴序列的恢复能力。这将包括通过新的“海洋卫星”卫星海岸监测工具利用卫星图像对复合海滩稳定性进行全球评估。分析最近（2021年6月）在Borth海滩安装的永久激光雷达站的数据，该站以1 Hz连续提供海滩剖面和波浪爬高数据。这项分析将侧重于风暴侵蚀和风暴后的反应。在威尔士和/或美国的2个或多个复合海滩上使用新开发的逐波鹅卵石跟踪方法进行实地实验，以更好地了解复合海滩脊的短期变化和单个鹅卵石的移动。测试并可能开发现有的最先进的XBeach-G海岸模型，以预测复合海滩的形态变化。如果成功的话，这将提高我们评估复合海滩对日益增加的风暴的脆弱性的能力，并为动态护岸海岸保护结构的设计提供一个工具。