The research plan will have two components. First, the existing modeling system will be enhanced for the NC estuaries, and numerical experiments will explore the sensitivities of estuarine flooding to the main drivers during storms. By varying systematically the atmospheric forcing, bottom friction, incoming river flows, and other parameters, we will improve our understanding of how storm surge is developed in these regions. Second, the modeling system will be extended to consider density-driven circulation and salinity transport, by leveraging earlier work for estuarine circulation in the northern Gulf. It is known that horizontal salinity transport during storms can threaten marine life and vegetation, but there is not currently a modeling system that can predict both transport and overland flooding. This project will combine those processes and explore questions about stratification during storms. While these interactions are important in estuaries along the U.S. Gulf and Atlantic coasts, they are especially important for the NC estuaries and their nearby communities, which have been devastated by storms in recent years.
The project will also have an extensive education component. Via collaboration with the Coastal Studies Institute, we will develop and implement lesson plans for storm surge and coastal flooding. It is expected that this new program will engage with more than 300 students in northeastern NC. The research team is well-positioned to contribute to these outreach activities, thus benefiting coastal communities in NC.
JC Dietrich, RJ McCord. “Improving Predictions of Estuarine Flooding and Circulation during Storms.” National Oceanic and Atmospheric Administration, North Carolina Sea Grant, 2020/02/01 to 2022/01/31, $119,370 (Dietrich: $99,610).
Averaging techniques are used to generate upscaled forms of the shallow water equations for storm surge including subgrid corrections. These systems are structurally similar to the standard shallow water equations but have additional terms related to integral properties of the fine-scale bathymetry, topography, and flow. As the system only operates with coarse-scale variables (such as averaged fluid velocity) relating to flow, these fine-scale integrals require closures to relate them to the coarsened variables. Closures with different levels of complexity are identified and tested for accuracy against high resolution solutions of the standard shallow water equations. Results show that, for coarse grids in complex geometries, inclusion of subgrid closure terms greatly improves model accuracy when compared to standard solutions, and will thereby enable new classes of storm surge models.
