Modeling Shoreline Morphological Evolution

海岸线形态演化建模

• 批准号: 1430913
• 负责人: Steve Elgar
• 金额: $ 69.5万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1430913&HistoricalAwards=false
• 关键词: Modeling; Shoreline; Morphological; Evolution

Many coastal areas are undergoing tremendous morphological change, resulting in deterioration of habitats and livelihoods, and altering the exchanges between land and ocean. For example, near Katama Bay, Martha's Vineyard, Massachussetts, sediment transport and morphological evolution is affecting water quality, oyster farms, tourism, and homes and structures. Waves from Hurricanes Irene and Sandy combined with strong currents caused 2.5 meter of erosion and accretion near Katama Inlet. In addition, the inlet is migrating hundreds of meters per year, and eventually will close until a storm again breaches the barrier beach separating the bay from the ocean. This project will use a combination of existing field observations and numerical model simulations to determine the causes of such morphological evolution. By investigating the effects of tides, waves, and currents on the dynamic coast of Martha's Vineyard, this research project will lead to an improved understanding of the processes driving shoreline evolution on ocean beaches and in or near inlets. The team will collaborate with U.S. Geological Survey scientists on model development for addressing a range of future scenarios and will work with local stake holders and managers to provide simulations and information about possible changes to the shoreline in response to different forcing and management choices, as well as to help plan for inlet closings and the associated changes in water quality and access. The project will also produce video lessons for high school students on relevant STEM topics.The study will address the hypotheses that: (i) migration of the inlet is owing to a combination of large nor'easters and hurricanes, more frequent, but more moderate wave events, and strong tidal flows, (ii) the timing of storms relative to flood and ebb flows and the storm duration are important to the morphological evolution, (iii) accretion inside the bay is caused by sand carried alongshore and subsequently transported into the inlet during flood flows, and (iv) closure of the inlet occurs when a large storm coincides with one or more spring flood tides, carrying sand into the inlet. The large morphological signal combined with existing observations of waves, currents, and the changing bathymetry make this site an ideal location to address hypotheses for shoreline morphological evolution, to calibrate, test, and improve numerical models that simulate the observed evolution, and to use models to predict future changes for different scenarios. Although this study will focus on the Martha's Vineyard site where there is substantial observational data and model infrastructure, the results will be applicable to a wide range of shoreline systems, with or without inlets. The dominant processes may differ from site to site, but the fundamental physics incorporated in the model are similar.

许多沿海地区正在经历巨大的形态变化，导致栖息地和生计恶化，并改变陆地和海洋之间的交换。例如，在马萨诸塞州玛莎葡萄园岛卡塔马湾附近，沉积物迁移和形态演化正在影响水质、牡蛎养殖场、旅游业以及住宅和建筑。飓风“艾琳”和“桑迪”带来的波浪与强流相结合，在卡塔马湾附近造成了 2.5 米的侵蚀和堆积。此外，入口每年移动数百米，最终将关闭，直到风暴再次冲破分隔海湾与海洋的屏障海滩。该项目将结合现有的现场观测和数值模型模拟来确定这种形态演变的原因。通过研究潮汐、波浪和洋流对玛莎葡萄园岛动态海岸的影响，该研究项目将加深对驱动海滩和入口内或附近海岸线演变的过程的了解。该团队将与美国地质调查局的科学家合作开发模型，以应对一系列未来情景，并将与当地利益相关者和管理者合作，提供有关海岸线可能发生变化的模拟和信息，以应对不同的强迫和管理选择，并帮助规划入口关闭以及水质和通道的相关变化。该项目还将为高中生制作有关 STEM 主题的视频课程。该研究将提出以下假设：(i) 入口的迁移是由于大型东北风和飓风、更频繁但更温和的波浪事件以及强潮汐的共同作用造成的，(ii) 风暴相对于洪水和落潮的时间以及风暴持续时间对形态演化很重要，(iii) 海湾内的吸积作用 海湾是由沿岸携带的沙子造成的，随后在洪水流动期间被输送到入海口，并且（iv）当一场大风暴与一次或多次春潮同时发生时，入海口关闭，将沙子带入入海口。大的形态信号与现有的波浪、水流和变化的水深观测相结合，使该站点成为解决海岸线形态演化假设、校准、测试和改进模拟观测到的演化的数值模型以及使用模型预测不同场景的未来变化的理想地点。尽管这项研究将重点关注拥有大量观测数据和模型基础设施的玛莎葡萄园岛，但结果将适用于各种海岸线系统，无论有或没有入口。不同地点的主导过程可能有所不同，但模型中包含的基本物理原理是相似的。