Coastal flooding seems like an unpredictable event, a natural disaster that occurs randomly. But UCF researcher Ivan Haigh has found that recurrent coastal floods actually occur at highly predictable times.
In a recent study published in Nature Communications, Haigh and a team of international researchers demonstrate that coastal flooding is prone to transpire at certain times of day, reflecting the timing of the tides. While previous research has largely focused on the seasonal timing of river and coastal flooding, this is the first study to show that impact-causing floods have predictable daily timing across regions.
“Floods have traditionally been viewed as primarily weather-driven and therefore relatively unpredictable in their exact timing,” Haigh says. “But surprisingly little attention has been paid to what hour of the day flooding occurs. Another reason is the way we measure flooding. We commonly talk about the number of ‘flood days’ per year. Once an event is reduced to a flood day, the information about whether the flooding happened at 3 a.m., 8 a.m. or 3 p.m. disappears.”
Using tide gauge data and flood event records from the U.S. and the U.K., the researchers found clear patterns in the appearance of floods. For example, in Boston, floods occur predominantly around noon and midnight while in Southern California, they are more common in the morning. In Florida, the timing can vary along the coastline because the tides differ from location to location. Along the Atlantic Coast and down toward the Florida Keys, coastal flooding is moderately predictable but along the Gulf Coast, flooding is less predictable.
Haigh says this predictability tends to be determined by the tides.
“In many locations, tides determine whether storm surge is sufficient to push water levels above flood thresholds,” Haigh says. “As a result, even storm-driven flooding often inherits the timing of the tides.”
The researchers also found that this phenomenon isn’t unique to locations that experience semidiurnal tides, which consist of two high tides and two low tides each day. It also happens in places with diurnal tidal systems, with one high tide and one low tide per day, because of the way different tidal signals interact.
As sea levels continue to rise, Haigh says that coastal flooding is increasingly occurring without storms to spur them on, making the findings of his research more significant.
“This matters because timing influences impacts,” Haigh says. “The same flood can have very different consequences if it occurs during the morning commute, business hours or in the middle of the night. Understanding these temporal patterns could improve flood forecasting, emergency planning, infrastructure operations and long-term coastal adaptation.”
Haigh says that this work could make existing flood forecasts more predictable, providing more warning before disasters occur. This can help people, businesses and emergency managers anticipate disruption and plan accordingly.
This information is also likely to become more useful as sea levels rise.
“Higher mean sea levels signify that it will take only a relatively small weather contribution or sometimes simply a very high astronomical tide to cross a flood threshold,” Haigh says. “Understanding exactly when those critical tidal windows occur could therefore become an increasingly important component of coastal flood forecasting and preparedness.”
About the Researcher
Professor Ivan D. Haigh is a prominent coastal and physical oceanographer. Born in Zambia, he moved to the U.K. at 19 and earned his bachelor’s degree in oceanography and mathematics, followed by a Ph.D. from the University of Southampton. After completing a postdoctoral fellowship in Western Australia, he returned to Southampton as a lecturer and rose to associate professor in 2016 before becoming full professor in sea level and coastal impacts in 2021. In 2022, he became the director of the Center for Doctoral Training for Resilient Flood Futures. Prior to academia, he also worked as a numerical modelling consultant with Associated British Ports Marine Environment Research. Haigh joined the University of Central Florida in 2025, as the director of the Center for Integrated Coastal Research.
- Written by Marisa Ramiccio