Waves Across Shore Platforms

岩石海岸线的特点通常是悬崖前面的潮间带海岸平台和发生沿着20%的英格兰和威尔士的海岸线。这些海岸平台倾向于平缓倾斜，并且它们总是代表流体动力学上非常粗糙的表面。悬崖和海岸平台是动态联系在一起的，因为平台的特性直接控制着波浪在其上传播的转化过程，从而控制着对悬崖的影响和悬崖的侵蚀。对于岩石海岸，这种转化过程几乎没有研究过。该项目的总体目标是提高对岩石海岸平台波浪变形过程的理解和建模能力。这项研究不仅将有利于海岸工程界，有助于更好的海岸管理和规划，而且也将有利于其他海岸科学家，包括地质学家，地貌学家和生态学家。我们的总体假设是，跨越海岸平台的波浪谱的转换主要受平台的海拔，坡度和宽度以及其表面的粗糙度控制。我们认为，这是可行的模型波的转换过程中，从而能量输送到悬崖的基础上，使用现有的数值波模型后，适当的参数化的平台表面的床摩擦。我们进一步建议，可以参数化的基础上的海岸平台的特点，即其梯度和粗糙度（微地形）的平台表面的底摩擦。我们的目的是在一系列波浪/潮汐条件下对6个不同海岸平台的波浪变形进行全面详细的现场测量，并从我们的观察中得出普遍有效的原则，更好地描述和预测岩石海岸平台的波浪变形过程。这些为期8天的实验将涉及部署一系列仪器，包括测量波浪和水位的压力传感器，记录近岸海流的声学海流计，用于监测波浪破碎模式和波浪爬高的数字摄像机，一个激光扫描仪，用于测量冲动力学和地面激光雷达系统，现场数据将用于量化由河床摩擦和波浪破碎引起的波浪能量耗散，耗散率将用于使用线性波浪理论反算波浪摩擦系数。反过来，所获得的波浪摩擦系数将与整体形态和微地形相关的海岸平台表面的粗糙度相关。改进的波浪摩擦参数化将在开放源代码的XBeach数值模型中实现，该模型将用于6个地点中的每一个，以评估海平面变化对波浪能量输送到悬崖底部的影响，以探索海平面上升对海岸悬崖衰退的潜在影响。该项目涉及来自普利茅斯大学、班戈尔大学和奥克兰大学的多学科研究团队，和Delaware（荷兰）。该项目将得益于两名海洋学家、两名海岸工程师、两名自然地理学家和一名地质学家的互补专长，他们都在与当前项目直接相关的研究领域有着良好的业绩记录：实地实验、近岸和碎浪带动态、岩石海岸过程和数字建模。主办机构还拥有一个实验基础设施，用于研究浅水海洋学过程的实地考察，在英国首屈一指，非常适合支持拟议的研究项目。研究基础设施和研究人员的综合实力，以及研究主题的相关性，使其成为一个低风险高影响力的项目。

Rocky coastlines are generally characterised by cliffs fronted by intertidal shore platforms and occur along 20% of the coastline of England and Wales. These shore platforms tend to be gently-sloping and they invariably represent hydrodynamically very rough surfaces. Cliffs and shore platforms are linked dynamically because the platform characteristics directly control the transformation processes of waves propagating across it, and thus the impact on the cliff and cliff erosion. For rocky shores this transformation process is virtually unstudied. The general aim of this project is to increase both understanding and modelling capability of wave transformation processes across rocky shore platforms. The research will not only benefit the coastal engineering community and contribute to better coastal management and planning, but will also benefit other coastal scientists, including geologists, geomorphologists and ecologists.Our overarching hypothesis is that the transformation of the wave spectrum across shore platforms is primarily controlled by the elevation, gradient and width of the platform, and the roughness of its surface. We consider that it is feasible to model this wave transformation process, and thus energy delivery to the base of the cliff, using existing numerical wave models after appropriate parameterisation of the bed friction of the platform surface. We further propose that the bed friction of the platform surface can be parameterised based on the characteristics of the shore platform, namely its gradient and roughness (micro-topography). Our intention is to conduct comprehensive and detailed field measurements of wave transformation across 6 different shore platforms under a range of wave/tide conditions and derive universally valid principles from our observations that better describe and enable the prediction of wave transformation processes across rocky shore platforms. Each of these 8-day experiments will involve deployment of a range of instruments, including pressure sensors to measure waves and water levels, acoustic current meters to record nearshore currents, digital video cameras for monitoring wave breaker patterns and wave runup, a laser scanner for measuring swash dynamics and a terrestrial LiDAR system for making high-resolution measurements of the shore platform topography.The field data will be used to quantify wave energy dissipation by bed friction and wave breaking, and the dissipation rates will be used to back-calculate wave friction factors using linear wave theory. In turn, the obtained wave friction factors will be correlated to the roughness of the shore platform surface related to the overall morphology and micro-topography. The improved wave friction parameterisation will be implemented in the open-source XBeach numerical model and the model will be used for each of the 6 sites to evaluate the effect of changing sea level to the wave energy delivery to the cliff base to explore the potential effect of rising sea level on coastal cliff recession.This project involves a multi-disciplinary research team from the Universities of Plymouth, Bangor and Auckland, and Deltares (Netherlands). The project will benefit from the complementary expertise of two oceanographers, two coastal engineers, two physical geographers and one geologist, all with proven track records in research areas that have a direct bearing on the current project: field experimentation, nearshore and surf zone dynamics, rocky coast processes and numerical modelling. The hosting institution also has an experimental infrastructure for studying shallow water oceanographic processes for fieldwork that is second to none in the UK, and is ideally suited to support the proposed research project. The combined strength in research infrastructure and researchers, as well as the relevance of the research topic, makes this a low-risk high-impact project.