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Researchers have developed a comprehensive model to hindcast nearly four decades of water-level data for the Southeast Atlantic coastline of the United States. Spanning the stretch from the entrance of Chesapeake Bay to the southeastern tip of Florida, the research offers vital insights into the complex factors driving coastal processes in the region.

Study area for Modeling Coastal Flooding Dynamics Along the U.S. Southeast Atlantic Coast
Study region with GTSM-ERA5 output locations marked as black circles and tide gauge locations marked as blue squares.

Led by a team of scientists from USGS and Deltares, the study utilized a sophisticated modeling framework combining a global-scale hydrodynamic model, a global wave model, a novel ensemble-based tide model, and statistical corrections to enhance the accuracy of water-level predictions. The hindcasted data were integrated to analyze the various components contributing to extreme water levels, including surge, tides, and wave forces.

One of the key findings of the research is the identification of compound events, where surge, tide, and wave forces act in concert to exacerbate flooding. The researchers found that the significance of these water-level components varies spatially along the coastline. Tides were found to play a more dominant role in the central region of the study area, while non-tidal residual water levels were more pronounced in the north. Waves, on the other hand, exerted significant influence in both the northern and southern extremities of the study area.

Hurricanes emerged as the primary drivers of the most extreme water-level events within the region. However, the research also highlighted the importance of non-hurricane events in producing more frequent to mid-level extreme water-level events. This nuanced understanding of the diverse range of events contributing to coastal flooding is crucial for effective hazard mitigation and risk assessment strategies. This research also sets the stage for future efforts expanding this analysis to the larger United States as well as considering the effects of climate change on total water level components. 

"Our study provides a robust analysis of the complex oceanographic factors shaping coastal flood events along the Southeast Atlantic coast,” said Kai Parker, USGS Oceanographer and lead author of the study. “By demonstrating the relative importance of different water-level components and their spatial variations, we aim to support critical coastal research goals, including landscape change assessment and community risk evaluations."

The comprehensive dataset generated through this research is expected to serve as a valuable resource for a wide range of applications, including coastal hazard research, infrastructure planning, and community resilience efforts. By improving our understanding of coastal flooding dynamics, this study represents a significant step forward in mitigating the impacts of rising sea levels and extreme weather events along the US Southeast Atlantic coastline. 

Read the study in Natural Hazards: Relative contributions of water-level components to extreme water levels along the US Southeast Atlantic Coast from a regional-scale water-level hindcast


Graph showing component contributions to extreme water levels
Component contributions to extreme water levels. Panel (a) shows GTSM-ERA5 stations (in black) with highlighted “multi-POT” node locations marked in red and numbered to correspond with panel (c). Panel (b) shows the average contribution to MWLs for the top 38 events (equal to the number of simulated years) at each station. Panel (c) shows the contribution to extreme MWLs for the max event (top bar) and binned events ranging from 5th largest to 60th largest. Binned values are calculated by averaging the 10 events bracketing the event rank of interest (e.g., the plotted bar for rank “15” is the average of all events from rank 10–20).

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