Synchronization of Transport And Supply: The Role of Nearshore Processes In Beach-Dune Interaction

运输和供应的同步：近岸过程在海滩-沙丘相互作用中的作用

• 批准号: 0920851
• 负责人: Christopher Houser
• 金额: $ 4.73万
• 依托单位: Texas A&M Research Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2011-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0920851&HistoricalAwards=false
• 关键词: Synchronization; Transport; Supply; Role; Nearshore

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Existing beach-dune models do not consider how and when sediment gets transferred to the backshore where they become available for transport by the wind. Rather, existing models largely ascribe regional variations in dune morphology to fixed constraints on the beach slope and sediment budget. The lack of information in this regard remains a central barrier to the development of a theory of beach-dune interaction that can form the basis of effective predictive models that can be translated across scales and between sites. Recent (process-scale) transport studies have shown that the transfer of sediment is both spatially variable and temporally intermittent as a result of transport limitations across the beachface. While these studies have identified varied controls on sediment transport and exchange, there remains a limited capacity to predict the evolution of beach-dune systems, largely because the beachface tends to be viewed as a static transport surface and without regards to supply. Understanding beach-dune processes has important implications for understanding how barrier islands recover from tropical storms and hurricanes, which in turn determines how the next storm impacts the island. This project, conducted by Dr. Christopher Houser at Texas A&M University will confirm and quantify the role of nearshore processes and morphological change on the exchange of sediment between the beaches and dunes. The exchange of sediment between the beach and dune depends on the synchronization of transport potential and available sediment on the beachface as the beach-state evolves. The specific goals of this study are: (1) to quantify time-dependent variations in the morphology and volume of the beachface in relation to the wave forcing and changes in the morphology of the nearshore bars, (2) to identify and quantify the time-dependent controls on aeolian transport (e.g. beach geometry, moisture, lag, etc.) in relation to the transport potential (wind speed and direction), and (3) to determine if the delivery of sediment from the beach and accumulation in the dune depends on the synchronization of transport potential and available supply of sediment deposited by nearshore processes in the upper-foreshore and backshore. This study represents a fundamental change in understanding of the beach-dune system. While process-geomorphologists are accustomed to thinking about small-scale processes as the building blocks of landforms, they typically consider these processes independent of the collective context, the specific landscape in which they are acting, to make sense to the evolution of landforms. Dune recovery requires sediment to be delivered first to the backshore by nearshore (surf and swash) processes and then delivered to the dune by the wind. With few exceptions, little attention has been paid to the mechanisms of dune recovery following storms, despite the importance of dune recovery to the impact of the next storm. Characterizing the factors that control the rate and mechanism of barrier island dune recovery is of great interest to coastal managers who need a means to predict the type of impact expected during the next storm and in determining if beach or dune restoration is required to protect property and infrastructure. In this respect, the study provides benefits to the communities of geographers, engineers and planners concerned with various aspects of beach and dune management.

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。现有的海滩沙丘模型没有考虑沉积物如何以及何时转移到后滨，在那里它们可以被风运输。 相反，现有的模型在很大程度上归因于沙丘形态的区域变化，固定的限制海滩坡度和沉积物预算。 缺乏这方面的信息仍然是发展海滩沙丘相互作用理论的一个主要障碍，而海滩沙丘相互作用理论可以构成有效的预测模型的基础，这些模型可以在不同尺度和不同地点之间进行转换。最近的（过程规模）运输研究表明，沉积物的转移是空间可变的和时间间歇性的整个海滩的运输限制的结果。 虽然这些研究确定了对沉积物迁移和交换的各种控制，但预测海滩沙丘系统演变的能力仍然有限，主要是因为海滩表面往往被视为静态的迁移表面，而不考虑供应。 了解海滩沙丘过程对于了解屏障岛屿如何从热带风暴和飓风中恢复具有重要意义，这反过来又决定了下一场风暴如何影响岛屿。 该项目由得克萨斯州农工大学的克里斯托弗·豪泽博士进行，将确认和量化近岸过程和形态变化对海滩和沙丘之间沉积物交换的作用。海滩与沙丘之间的泥沙交换取决于滩面输沙势与可利用泥沙的同步性。 本研究的具体目标是：（1）量化与波浪作用力和近岸沙坝形态变化相关的海滩面形态和体积随时间的变化;（2）识别和量化与时间相关的风成输运控制因素（例如海滩几何形状、湿度、滞后等）;（3）确定海滩的沉积物输送和沙丘的堆积是否取决于上前滨和后滨近岸过程沉积的沉积物的输送潜力和可用供应的同步。 这项研究代表了对海滩沙丘系统认识的根本变化。 虽然过程地貌学家习惯于将小尺度过程视为地貌的组成部分，但他们通常认为这些过程独立于集体背景，即它们所处的特定景观，对地貌的演变有意义。沙丘恢复要求沉积物首先通过近岸（海浪和冲浪）过程输送到后海岸，然后通过风输送到沙丘。 除了少数例外，很少有人注意到沙丘恢复风暴后的机制，尽管沙丘恢复下一个风暴的影响的重要性。 沿海管理人员需要一种方法来预测下一次风暴期间预期的影响类型，并确定是否需要恢复海滩或沙丘以保护财产和基础设施，因此，确定控制障壁岛沙丘恢复速率和机制的因素具有极大的意义。 在这方面，这项研究为地理学家、工程师和规划人员提供了与海滩和沙丘管理各方面有关的好处。