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水和沉积物循环非常重要。然而，科学家们并不了解复杂的沿海地区（如沿海河流三角洲）的水如何对与冷锋相关的风做出反应。理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，恢复工作必须考虑冷锋的影响才能有效。该项目将调查这些问题，整个沿海路易斯安那州使用现场测量和风事件和水运动的建模。除了提高对复杂沿海地区水循环的理解外，该项目还将吸引利益攸关方参与，并向巴吞鲁日（路易斯安那州）的学童提供动手示范。大气冷锋是路易斯安那州沿海地区水循环和沉积物输送的主要驱动力，该地区由于相对海平面上升，海岸侵蚀和缺乏沉积物输入而经历快速土地流失。人们对理解和利用自然三角洲过程，通过沉积物转移来减轻土地损失以及风暴潮和盐水入侵的增加很感兴趣。河流三角洲包括相对较深的分流河道和与河道水力连接的浅水湿地。以前对由前缘通道产生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显著的变化（例如，沿海大陆架或开阔海湾）。深度的急剧变化，连通性的空间梯度，以及河流与海洋强迫的影响，使河流三角洲成为一个显着更复杂的异质环境，冷锋引起的环流尚未了解。这项建议将：1）确定水位如何在整个密西西比三角洲地区的锋面通道变化，2）确定如何明显的变化，深度在一个异质三角洲影响流体动力学引起的冷锋，和3）确定机制，控制通道湿地连接三角洲在冷锋。天气分析将集中在路易斯安那州沿海地区，而详细的实地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攸关方和沿海管理人员分发数字小册子，以及一个便携式风力造波罐，该罐将用于每年有200名本科生和2 500名K-8学生和教师参加的示范活动。该奖项反映了NSF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.