An interdisciplinary team of scientists have completed a comprehensive review of published numerical modeling efforts to assess the use of natural infrastructure for coastal compound flood mitigation.
Coastal flooding is often driven by a combination of factors, including precipitation, river discharge, storm surges, waves, and tides. The collective influence of these factors is referred to as compound flooding, and can amplify the overall impact of flooding on coastal communities. However, understanding and quantifying compound flooding is challenging, often involving the use of multiple numerical models, which can be coupled to represent hydrologic, hydraulic/hydrodynamic, and biological processes spanning the coastal ocean to rivers.
Compound flood models can also incorporate conventional, natural and hybrid infrastructure across the landscape to evaluate how these systems perform to mitigate compound flooding. Although natural ecosystems like tidal marshes and dunes are widely known to reduce storm surge, dissipate wave energy, and decrease erosion, these benefits are often not well quantified in the context of compound flooding.
The team performed a systematic review to understand the spatial scale (i.e., regional vs local), geographic location, numerical models, and habitats being considered in the scientific literature from 2009 to 2023. Of the 141 publications reviewed, only nine percent addressed compound flooding, and most (61 percent) were carried out at the local scale (e.g., individual coasts, cities, and bays). In response to these findings, the team discussed a conceptual framework for developing holistic, coupled models that can better represent the flood mitigation performance of natural infrastructure.
In particular, this framework emphasizes the need to better represent ecological factors and feedback (e.g., vegetation characteristics and seasonality), improve input data collection, and build consistency in model coupling approaches that more appropriately represent the combination of complex flood drivers. Lastly, to ensure that compound flood modeling can regularly be applied to mitigation activities and improve flooding forecasts, the team recommended co-creating this modeling framework with model output end users.
By investing in coordinated advancements in model coupling across our nation’s coasts, we will further accelerate the assessment of flood mitigation strategies and improve model output integration into forecasts and public warnings.
This project is led by Hamed Moftakhari (University of Alabama) and co-supported through NCCOS and the Cooperative Institute for Research to Operations in Hydrology (CIROH). NCCOS was congressionally directed in fiscal year 2024 to allocate $1M to CIROH, a partnership between NOAA and The University of Alabama. CIROH is a national consortium committed to advancing water prediction and building community resilience to water-related challenges.
Citation: Radfar, S., Mahmoudi, S., Moftakhari, H., Meckley, T., Bilskie, M.B., Collini, R., Alizad, K., Cherry, J.A., and Moradkhani, H. 2024. Nature-based solutions as buffers against coastal compound flooding: Exploring potential framework for process-based modeling of hazard mitigation. Science of The Total Environment, Volume 938, 173529. https://doi.org/10.1016/j.scitotenv.2024.173529