Role of Free and Forced Boundary Conditions on Beachface Evolution

本研究项目将研究近岸剖面的演变如何通过冲刷带内沉积物的供应和运输的变化来确定海滩侵蚀和加积。 缺乏有关这一套过程的信息仍然是一个中心的障碍，发展的理论，沿海演变和海滩沙丘的相互作用，可以跨尺度和现场翻译。 大多数冲流区的研究都考虑了流体动力学和运输，而没有明确考虑收集现场观测数据的海滩状态和边界条件的动态性质。 在这个项目中，研究人员将评估冲击区流体动力学和沉积物输运如何依赖于入射波场在不断发展的近岸剖面上的转换。 该项目将涉及一个复杂的实地研究，同时监测沼泽区的水动力学，沉积物运输，并响应海滩状态和近岸形态的变化床高程变化。 将使用的现场仪器包括超声波距离传感器和水流计在冲浪区，波浪和潮汐传感器在内冲浪区，以及地面激光扫描仪和远程相机，以监测海滩的演变。 预计该项目将产生丰富的数据集，反映不断变化的沼泽区流体动力学和沉积物输运，以应对近岸剖面的变化，这是开发海滩演变预测模型的重要而独特的第一步，热带风暴或飓风对屏障岛的影响取决于海滩和沙丘系统自上次风暴以来的恢复能力。 沙丘的恢复取决于沉积物从近岸转移到海滩，在海滩上，沉积物可能被风吹到后滨和沙丘。 因此，控制沼泽区演变速度和机制的因素对沿海管理人员来说非常感兴趣，他们需要改进的信息和模型来预测后续风暴期间预计的影响类型，并确定是否需要恢复海滩或沙丘以保护财产和基础设施。 该项目也将为有前途的研究生提供有价值的教育和培训。

This research project will examine how the evolution of the nearshore profile determines beachface erosion and accretion through changes in both the supply and transport of sediment within the swash zone. The lack of information about this set of processes remains a central barrier to the development of theories regarding coastal evolution and beach-dune interaction that can be translated across scales and field sites. Most swash zone studies have considered hydrodynamics and transport without explicit consideration of the beach-state in which the field observations were collected and the dynamic nature of this boundary condition. In this project, the researchers will assess how swash-zone hydrodynamics and sediment transport are dependent on the transformation of the incident wave field across the evolving nearshore profile. The project will involve a complex field-study that simultaneously monitors swash-zone hydrodynamics, sediment transport, and bed elevation change in response to changes in beach-state and nearshore morphology. Field instruments that will be used include ultrasonic distance sensors and current meters in the swash zone, wave and tide sensors in the inner-surf zone, and a terrestrial laser scanner and remote cameras to monitor beachface evolution. The project is expected to yield a rich dataset of evolving swash-zone hydrodynamics and sediment transport in response to changes in the nearshore profile, an important and unique first step to developing a predictive model of beachface evolution.The impact of a tropical storm or hurricane on a barrier island is dependent on the ability of the beach and dune system to recover since the last storm. The recovery of dunes is dependent on the transfer of sediment from the nearshore to the beachface, where it may become available for aeolian transport to the backshore and dunes. The factors that control the rate and mechanism of swash-zone evolution therefore are of great interest to coastal managers who need improved information and models for predicting the type of impact expected during succeeding storms and for determining whether beach or dune restoration is required to protect property and infrastructure. This project also will provide valuable education and training for a promising graduate student.