NOAA Validates Sea Level Data for Future Flood Risk

By NOAA’s Ocean Service.

More than 40 years of data verified to accurately assess flood-risk changes on Atlantic, Caribbean and Gulf of Mexico coasts.

A team of NOAA and university sea level rise experts completed a study of more than four decades of water level data, validating foundational research for flood-risk assessment tools. The study verified the accuracy of NOAA’s modeling of historical coastal water level information for areas along the Atlantic and Caribbean coasts and the Gulf of Mexico.

The study used coastal water level stations to determine how coastal flooding has changed over time to benefit NOAA’s current flood-risk assessment tools. The findings are published in the latest edition of Frontiers In Marine Science in an article entitled “Assessment Of Water Levels From 43 Years of NOAA’s Coastal Ocean Reanalysis (CORA) for the Gulf Of Mexico and East Coasts.”

The study examines the impact CORA can have as local and state authorities address increasing flood impacts. Coastal water level information is crucial for understanding flood occurrences, changing flood risks, and to predict future flood likelihood. Scientists from NOAA, the University of Hawaii and the University of North Carolina (UNC) contributed to the study, led by Linta Rose of the University of Hawaii. UNC’s Renaissance Computing Institute provided modeling expertise and high-performance computers to perform the analysis.

“The CORA project couples NOAA’s authoritative data with modern modeling to create data between water level stations,” said NOAA oceanographer Analise Keeney. “It equitably serves coastal communities that need detailed flooding information to plan for and mitigate the impacts of sea level rise.”

The study assesses a preliminary version of CORA for water levels along the Gulf of Mexico and the Atlantic and Caribbean coasts, where in many locations, coastal flooding is increasing dramatically. Using output from CORA of historical oceanic conditions, the authors assessed hourly coastal water levels over a 43-year period from 1979 to 2021.

The scientists found that CORA more accurately captures observed coastal water level variability compared to other global water level reanalysis, and shows that NOAA can help quantify flooding risks in areas where long-term measurements are unavailable. The findings prove the utility of CORA’s data on coastal water levels and waves to assess changes in flood risks. Long-term sea level variability is included by integrating water level observations from NOAA’s National Water Level Observation Network.

“The results from this collaborative research establish the high quality of the CORA water level data, and that these data can be used to build the next generation of NOAA coastal flood products,” said Gregory Dusek, Ph.D., chief scientist of NOAA’s Center for Operational Oceanographic Products and Services. “We look forward to the availability of these CORA datasets in the coming months for the research community to further explore.”

Preliminary CORA datasets were validated by comparison with NOAA’s verified water level observations. The comparison showed CORA performs better than leading global ocean reanalyses in capturing the variability on monthly, seasonal and longer-term time scales and trends.

This preliminary validation provides confidence that CORA will help enhance flood-risk assessment and mitigation tools like NOAA’s Monthly High Tide Flooding Outlook along parts of the U.S. coast that do not have historical water level observations.