Collaborative Research: Hydrologic Dynamics in a Coastal Aquifer During an Extreme Multi-Hazard Coastal Storm

沿海人口的增长导致沿海水质因营养物质和其他污染物的过量输入而受损。新鲜的地下水从陆地流向海岸，并通过海底排放到海洋，可以成为沿海地表水的重要化学物质来源，导致藻类繁殖、鱼类死亡和生物多样性丧失。海滩含水层提供了一种宝贵的生态服务，在地下水污染物排放到海洋之前进行化学过滤。滩涂含水层的化学反应性取决于地下水的流动行为和淡水与海水的混合。本研究的目的是利用野外测量和数值模型来了解极端多灾害性海岸风暴（包括风暴潮、强降水和海岸侵蚀）对海滩含水层地下水流动和混合模式的影响。现场观察将在北卡罗来纳州达克附近的陆军工程兵团现场研究设施进行。这项工作将有助于估计未来由于更频繁和更强烈的风暴、海岸侵蚀和海平面上升而向沿海水域释放的营养物质和污染物。该研究的目的是整合水文地质和物理海洋学方法，以获得对强烈海岸风暴期间海滩含水层地下水动力学和氧化还原行为的新认识。该研究将结合野外观测和数值模型，以1)表征风暴潮、极端降水和海岸形态变化对滩地地下水动态的个别和综合影响；2)评估不同风暴和形态情景下的含水层恢复时间；3)评估极端风暴事件期间和之后的盐水-淡水混合时空格局。这项研究将作为近岸事件实验（DUNEX）的一部分在陆军工程兵团野外研究设施进行，利用气象、海洋学和地貌学测量以及由美国海岸研究计划（USCRP）资助的后勤支持。该研究适用于海岸管理者，旨在1)评估沙滩作为陆地和海洋之间化学和物质通量调节剂的生态价值，2)估计沿海风暴期间和之后化学物质释放到沿海水域的时间，3)预测由于更频繁和更强烈的风暴，海岸侵蚀和海平面上升而导致的化学物质输送的变化，以及4)设计风暴后海滩营养策略以促进海滩含水层的生态服务。该研究将与USCRP在实验期间协调的教育机会相结合，包括讲座、学生、沿海专业人员和公众的实践活动。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。

Coastal population growth has led to coastal water quality impairment from excess input of nutrients and other contaminants. Fresh groundwater flowing from land to the coast and discharging through the seabed to the sea can serve as a significant source of chemicals to coastal surface water, resulting in algal blooms, fish kills, and loss of biodiversity. Beach aquifers provide a valuable ecological service of chemically filtering groundwater contaminants prior to discharge to the ocean. The chemical reactivity of beach aquifers depends on groundwater flow behavior and mixing between fresh water and seawater. The objective of this study is to use field measurements and numerical models to understand the effects of extreme multi-hazard coastal storms (including surge, heavy precipitation, and coastal erosion) on groundwater flow and mixing patterns in beach aquifers. Field observations will be conducted at the Army Corps of Engineers Field Research Facility near Duck, NC. The work will help estimate future nutrient and contaminant release to coastal waters due to more frequent and intense storms, coastal erosion, and sea level rise. The objective of the proposed research is to integrate hydrogeological and physical oceanographic methodologies to obtain new understanding of groundwater dynamics and redox behavior in beach aquifers during severe coastal storms. The proposed study will combine field observations and numerical models to 1) characterize the individual and combined effects of storm surge, extreme precipitation, and coastal morphological change on beach groundwater dynamics, 2) assess aquifer recovery time for different storm and morphological scenarios, and 3) evaluate spatiotemporal patterns of saltwater-freshwater mixing during and after an extreme storm event. This study will take place as part of the DUring Nearshore Event eXperiment (DUNEX) at the Army Corps of Engineers Field Research Facility to leverage meteorological, oceanographic, and geomorphological measurements and logistical support funded by the U.S. Coastal Research Program (USCRP). The study is applicable to coastal managers aiming to 1) assess the ecological value of sandy beaches as moderators of chemical and material fluxes between land and sea, 2) estimate the timing of chemical release to coastal waters during and after coastal storms, 3) predict changes to chemical delivery due to more frequent and intense storms, coastal erosion, and sea level rise, and 4) design post-storm beach nourishment strategies to promote beach aquifer ecological services. The study will integrate with educational opportunities coordinated by USCRP during the experiment, including lectures, hands-on activities for students, coastal professionals, and the public.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.