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

由于营养物质和其他污染物的过量输入，沿海人口增长导致沿海水质受损。从陆地流向海岸并通过海床向海洋排放的新鲜地下水可作为沿海地表水的重要化学物质来源，导致藻类大量繁殖、鱼类死亡和生物多样性丧失。海滩含水层提供了宝贵的生态服务，在排放到海洋之前对地下水污染物进行化学过滤。海滩含水层的化学反应能力取决于地下水的流动行为和淡水与海水的混合。这项研究的目的是利用现场测量和数值模型来了解极端的多种危险的海岸风暴(包括潮汐、强降水和海岸侵蚀)对海滩含水层中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野外研究设施进行。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。拟议研究的目标是将水文地质学和物理海洋学方法结合起来，以获得对严重沿海风暴期间海滩含水层中地下水动力学和氧化还原行为的新理解。拟议的研究将结合现场观测和数值模型，1)描述风暴潮、极端降水和海岸地貌变化对海滩地下水动态的单独和综合影响，2)评估不同风暴和地形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咸水-淡水混合的时空模式。这项研究将作为陆军工程兵团野外研究设施近岸事件实验(DUNEX)的一部分进行，以利用由美国海岸研究计划(USCRP)资助的气象、海洋和地貌测量和后勤支持。这项研究适用于海岸管理者，目的是1)评估沙质海滩作为陆地和海洋之间化学和物质通量调节器的生态价值，2)估计沿海风暴期间和之后向沿海水域释放化学物质的时间，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产生的化学物质输送的变化，以及4)设计风暴后海滩营养战略，以促进海滩含水层的生态服务。这项研究将与USCRP在实验期间协调的教育机会相结合，包括为学生、沿海专业人员和公众提供讲座、动手活动。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.