Coastal flooding can seem unpredictable, but UCF Coastal researcher has found that recurrent coastal floods often occur at highly predictable times. Haigh, a professor in the Department of Civil, Environmental and Construction Engineering within UCF’s College of Engineering and Computer Science, recently led an international study examining how tides influence the daily impact of coastal floods.
In a recent study published in Nature Communications, Haigh and an international team of researchers found that coastal flooding tends to occur 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.
鈥淔loods have traditionally been viewed as primarily weather-driven and therefore relatively unpredictable in their exact timing,鈥� Haigh says. 鈥淏ut 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 鈥榝lood days鈥� 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.鈥�
Tides Create Predictable Patterns
Using tide gauge data and flood event records from the U.S. and the U.K., the researchers found clear patterns in when floods occur.
In Boston, for example, floods occur predominantly around noon and midnight, while in Southern California they are more common in the morning. In Florida, timing varies along the coastline because tides differ by location. Along the Atlantic Coast and toward the Florida Keys, coastal flooding is moderately predictable, while flooding along the Gulf Coast is less predictable.
Haigh says tides largely drive that predictability.
鈥淚n many locations, tides determine whether storm surge is sufficient to push water levels above flood thresholds,鈥� Haigh says. 鈥淎s a result, even storm-driven flooding often inherits the timing of the tides.鈥�
The researchers found that the phenomenon isn鈥檛 limited to locations that experience semidiurnal tides, which consist of two high tides and two low tides each day. It also occurs in places with diurnal tidal systems 鈥� with one high tide and one low tide per day 鈥� because of the way different tidal signals interact.
Why Flood Timing Matters
As sea levels rise, coastal flooding is increasingly occurring even without storms, making an understanding of when floods are likely to occur increasingly important.
鈥淭his matters because timing influences impacts,鈥� Haigh says. 鈥淭he 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
Knowing when coastal flooding is most likely to occur could help people, businesses and emergency managers better anticipate disruption and plan accordingly. That information could become even more useful as rising sea levels make it easier for tides and relatively small weather events to push water above flood thresholds.
鈥淗igher 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,鈥� Haigh says. 鈥淯nderstanding exactly when those critical tidal windows occur could therefore become an increasingly important component of coastal flood forecasting and preparedness.鈥�
About the Researcher
Professor Ivan Haigh is a professor and eminent coastal and physical oceanographer. A coastal and physical oceanographer, he earned his bachelor鈥檚 degree in oceanography and mathematics, and his Ph.D. from the 海角直播 of Southampton. He later served as a professor of sea level and coastal impacts at Southampton and directed its Center for Doctoral Training for Resilient Flood Futures. Haigh joined the 海角直播 in 2025, as the director of the Center for Integrated Coastal Research.
