Examining hydrodynamics and connectivity resulting from atmospheric frontal passages in a coastal river delta

该项目旨在了解冷锋如何影响沿海河流三角洲的水流运动。在潮汐较小的地区，如路易斯安那州沿海地区，与冷锋相关的风对整个地区的循环水和沉积物很重要。然而，科学家们并不了解复杂沿海地区的水，如沿海河流三角洲，是如何对与冷锋相关的风做出反应的。了解这种相互作用是很重要的，因为冷锋可能会导致海岸侵蚀，这是路易斯安那州的一个主要问题，而恢复工作必须考虑到冷锋的影响才能有效。该项目将通过实地测量和模拟风事件和水运动来调查路易斯安那州沿海地区的这些问题。除了提高对复杂沿海地区水循环的了解外，该项目还将吸引利益相关者，并为巴吞鲁日（路易斯安那州）的学童提供实践示范。大气冷锋是路易斯安那州沿海地区水循环和沉积物运输的主要驱动因素，该地区由于海平面相对上升、海岸侵蚀和缺乏沉积物输入而经历着快速的土地流失。人们对理解和利用自然三角洲过程有相当大的兴趣，通过泥沙转移来减轻土地损失，以及增加的风暴潮和盐水入侵。河流三角洲包括相对较深的分流河道和与河道水力相连的浅水湿地。以前对锋面通道造成的流体动力学的分析集中在相对均匀的环境上，这些环境在深度上没有相当大的变化（例如，沿海陆架或开阔的海湾）。深度的明显变化，连通性的空间梯度，以及河流与海洋作用力的影响，使河流三角洲成为一个更加复杂的非均质环境，冷锋诱发的环流尚未被理解。该提案将：1)确定密西西比河三角洲地区锋面通道的水位变化情况；2)确定冷锋诱导的非均质三角洲的深度变化如何影响水动力学；3)确定冷锋期间控制三角洲河道-湿地连通性的机制。天气分析将集中在路易斯安那州沿海地区，而详细的现场测量和数值模拟将集中在路易斯安那州的蜡湖三角洲。外联工作包括向当地利益相关者和沿海管理者分发数字小册子，以及一个便携式风力驱动的波浪箱，该箱将用于每年有200名本科生和2500名K-8学生和教师参加的示范活动。该提案由水文科学和物理海洋学项目共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project aims to understand how cold fronts affect water movement in coastal river deltas. In regions with small tides, such as coastal Louisiana, winds associated with cold fronts are known to be important for circulating water and sediment throughout the region. However, scientists do not understand how water in complex coastal regions, such as coastal river deltas, respond to winds associated with cold fronts. Understanding this interaction is important, because cold fronts may contribute to coastal erosion, a major issue in Louisiana, and restoration efforts must account for the effects of cold fronts to be effective. This project will investigate these issues throughout coastal Louisiana using field measurements and modeling of wind events and water movement. In addition to improving the understanding of water circulation in complex coastal regions, the project will also engage stakeholders and delivers hands-on demonstrations to Baton Rouge (Louisiana) schoolchildren. Atmospheric cold fronts are major drivers of water circulation and sediment transport in coastal Louisiana, a region experiencing rapid land loss due to relative sea level rise, coastal erosion, and lack of sediment input. There is considerable interest in understanding and using natural deltaic processes through sediment diversions to mitigate land loss, as well as increased storm surge and saline intrusion. River deltas comprise relatively deep distributary channels and shallow wetlands that are hydraulically connected to channels. Previous analyses of the hydrodynamics resulting from frontal passages have focused on relatively homogeneous environments that do not have considerable changes in depth (e.g., the coastal shelf or open bays). Stark changes in depth, spatial gradients in connectivity, and the impact of fluvial versus marine forcings make river deltas a significantly more complex heterogeneous environment where cold front-induced circulation is not yet understood. This proposal will: 1) determine how water levels vary throughout frontal passages across the Mississippi Delta Region, 2) determine how appreciable changes in depth across a heterogenous delta affect hydrodynamics induced by cold fronts, and 3) identify the mechanisms that control channel-wetland connectivity in deltas during cold fronts. Synoptic analyses will focus on the coastal Louisiana region while detailed field measurements and numerical modeling will focus on the Wax Lake Delta in Louisiana. Outreach efforts include digital brochures distributed to local stakeholders and coastal managers, as well as a portable wind-driven wave tank that will be used in demonstrations engaging 200 undergraduate students and 2,500 K-8 students and teachers on an annual basis. This proposal is co-funded by the Hydrologic Sciences and Physical Oceanography programs.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.