PREEVENTS Track 2: Collaborative Research: A Dynamic Unified Framework for Hurricane Storm Surge Analysis and Prediction Spanning across the Coastal Floodplain and Ocean

风暴驱动的沿海洪水受到许多物理过程的影响，包括河流排放、区域降雨、风、大气压力、波浪引起的形成、波浪上升、潮汐和基线海水水位波动。风暴潮业务模型，例如 NOAA 海洋预测中心（温带风暴潮业务预报系统）使用的模型，包含了各种此类过程，包括河流排放、大气风和压力、波浪和潮汐。然而，沿海潮汐模型通常不考虑沿海洪泛区降雨的影响，也不考虑海洋密度结构导致的背景水位波动。尽管如此，漫滩水文和海洋基线水位对河流和河口环境提供了重要的控制（例如，2017 年哈维飓风期间休斯顿大都市区和 2018 年佛罗伦萨飓风期间北卡罗来纳州所看到的巨大影响）。最近的事件表明，纳入所有相关物理过程的统一方法对于准确预测极端事件引起的沿海洪水至关重要。该项目将通过将水文学、水力学和波浪融合到动态统一计算框架中来应对这一挑战，该框架使用从深海到高地地区以及整个沿海洪泛区的非结构化网格。提高洪水风险管理者、保险业和城市规划者评估整个沿海洪泛区洪水风险的能力。改进的模型将为开发和建设实践提供更好的指导，有助于提高城市的韧性，并降低沿海人口和基础设施的风险。此外，这项工作将改善沿海洪水预报，使联邦、州和地方灾害管理人员能够优化发布疏散警报和应急计划。该项目促进的海洋环流、沿海水动力学和水文学建模界之间的合作将有助于支持雄心勃勃的项目，例如美国国家海洋和大气管理局国家水中心的国家综合水模型，该模型正处于水文学和沿海水动力学整合的初步阶段。在水文学、沿海流体动力学、物理海洋学和计算数学的交叉领域对学生进行培训，以帮助学术界、政府和工业界开发和应用更加复杂和先进的模型。所提出的统一框架将通过综合考虑沿海洪泛区降雨驱动的水文以及改善背景开放海水位来改善整个沿海洪泛区的预测水位梯度和流量。完善但粗糙的全球海洋模型将与高分辨率二维浅水方程模型异质耦合，以解释影响沿海水位的大规模斜压海洋过程。将开发异质物理之间的界面策略和条件，允许界面在从干燥到地表径流再到加压流的物理范围内在时间和空间上移动。随着风暴的演变，应用正确的物理学和相关的数学模型将产生更稳健、更准确的模型，以及更高效的模型。这将动态地解释漫滩上水的水文-水动力相互作用。动态负载平衡将考虑每组物理的广泛不同的计算（CPU）成本，并且物理的动态迁移将在异构并行计算环境中实现。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Storm-driven coastal flooding is influenced by many physical processes including riverine discharges, regional rainfall, wind, atmospheric pressure, wave-induced set up, wave runup, tides, and fluctuating baseline ocean water levels. Operational storm surge models such as those used by NOAA's Ocean Prediction Center (Extratropical Surge and Tide Operational Forecast System) incorporate a variety of these processes including riverine discharges, atmospheric winds and pressure, waves, and tides. However, coastal surge models do not typically incorporate the impact of rainfall across the coastal floodplain nor fluctuations in background water levels due to the oceanic density structure. Nonetheless, the floodplain hydrology and ocean baseline water levels provide vital controls in riverine and estuarine environments (e.g., the dramatic effect seen in the Houston metropolitan region during Hurricane Harvey in 2017 and in North Carolina during Hurricane Florence in 2018). Recent events have shown that a unified approach that incorporates all the relevant physical processes is critical for accurate predictive simulations of coastal flooding due to extreme events. This project will tackle this challenge by melding hydrology, hydraulics, and waves into a dynamic unified computational framework that uses unstructured meshes spanning from the deep ocean to upland areas and across the coastal floodplain. Improved capacity for flood risk managers, the insurance industry, and city planners to evaluate flood risk across the entire coastal floodplain. Improved models will lead to better guidance on development and construction practices, will help make cities more resilient and will reduce risk for coastal populations and infrastructure. In addition, this work will improve coastal flood forecasting enabling federal, state, and local disaster managers, to optimize issuing warnings for evacuation and emergency planning. The collaboration between the ocean circulation, coastal hydrodynamics, and hydrology modeling communities fostered by this project will help support ambitious projects such as NOAA's National Water Center's National Integrated Water Model, which is at the preliminary stages of integration of hydrology and coastal hydrodynamics. Training of students at the intersection of hydrology, coastal hydrodynamics, physical oceanography, and computational mathematics, to help develop and apply ever-more complex and advanced models in academia, government and industry.The proposed unified framework will improve the predicted water level gradient and flows throughout the coastal floodplain by integrally considering the rainfall-driven hydrology within the coastal floodplain as well as improving the background open ocean water level. Well-developed but coarse global ocean models will be heterogeneously coupled to high-resolution 2D shallow water equation models in order to account for large-scale baroclinic ocean processes that impact coastal water levels. Interface strategies and conditions between heterogeneous physics will be developed that allow the interfaces to move in time and space for the range of physics from dry to surface runoff to pressurized flow. Applying the right physics and associated mathematical models as the storms evolve will result in more robust and accurate models, as well as much more efficient models. This will dynamically account for the hydrologic - hydrodynamic interaction of water across the floodplain. Dynamic load balancing will account for widely varying computational (CPU) costs for each set of physics and the dynamic migration of the physics will be implemented within the heterogeneous parallel computing environment.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.