A new study from NC State and UNC-Chapel Hill reveals coastal flooding is markedly more frequent than traditional methods suggest, urging a reevaluation of flood monitoring and prediction techniques.
Flooding in coastal communities is far more common than earlier estimations indicated, according to new research from North Carolina State University and the University of North Carolina at Chapel Hill. The study also highlights significant shortcomings in traditional methods that use tide gauge data to measure flooding.
“Government agencies and researchers use data from tide gauges to measure water levels in coastal areas, then use that data to estimate flood frequency in the region,” corresponding author Miyuki Hino, an assistant professor of city and regional planning at UNC, said in a news release. “Those estimates are used both to assess how often flooding has taken place and to predict how often flooding may take place in the future. However, our study shows that this approach does not accurately capture how often flooding takes place or how long those floods last.”
Sea-level rise accounts for frequent flooding in coastal areas, even during ordinary rain showers or at high tide on sunny days, according to co-author Katherine Anarde, an assistant professor of coastal engineering at NC State, who noted that existing methodologies don’t address the new realities brought by rising sea levels.
“Our research shows you need land-based measures of flooding to capture the burden on coastal residents, which can inform policy and planning decisions moving forward,” Anarde added.
The study scrutinized the effectiveness of the National Oceanic and Atmospheric Administration (NOAA) High Tide Flooding threshold (HTF) and the National Weather Service’s minor flood threshold (NWS) in predicting land-based flooding.
The researchers deployed land-based sensors across Beaufort, Carolina Beach and Sea Level in eastern North Carolina, recording significant discrepancies between tide gauge data and actual flooding events.
For instance, the sensors documented 26 flood days in Beaufort, 65 in Carolina Beach and 128 in Sea Level over a year. In stark contrast, the closest tide gauge indicated much lower flooding instances: just nine flood days according to HTF and only 31 according to NWS in Sea Level.
“Essentially, the thresholds don’t adequately account for how long it takes water to drain off of land,” Hino added, suggesting that comprehensive, accurate data are crucial for developing resilient communities.
The study, published in the journal Communications Earth & Environment, argues for better monitoring techniques to inform resource allocation and infrastructure planning to counteract increasing flood events.
Supported by various grants from entities like the U.S. Department of Homeland Security and the National Science Foundation, Anarde and Hino stress the necessity of tailored solutions for each community, drawing on enhanced data accuracy.
“Every community is unique, so there’s no one-size-fits-all solution,” concluded Hino. “But with more accurate data, we can help communities assess what response strategy is best for them, now and in the future.”
Source: North Carolina State University