University Researchers Identify Causes of Increasing Coastal Nuisance Flooding

Minor flooding incidents in U.S. shorelines, known as coastal nuisance flooding, have been noted to have increased in recent years due to rises in sea level. Although not devastating in nature, nuisance floodings have overloaded storm water systems and resulted to flooded roads that could provide additional breeding grounds for mosquitoes and harmful microorganisms.

The University of Central Florida conducted a study of the continental U.S. coastlines in 40 locations along the Atlantic, Gulf and Pacific coasts, using tidal gauge data in said locations spanning at least 70 years. They then compared water levels based on two different scenarios, one in which the tidal range had not changed and one where it has. The research work was funded by the National Science Foundation.

Tide ranges as explained by the researchers are the height differences between low tides and high tides. Tide ranges could increase in certain areas but can also decrease in others.

What Causes Tide Ranges to Change?

The study found that in nearly half of the 40 locations, there had been more nuisance flooding occurrences due to higher local tide ranges. In coastal areas and estuaries, changes in local tide range often occur after the channels have been dredged, or when development takes place after lands are reclaimed. Tide range changes can also occur when river flows change.

The study concluded that higher local tide ranges occur, most likely as a result of human modifications in estuaries and coastal areas. These then have increased the number of nuisance flooding days in many U.S. coastal locations.

Thomas Wahl, a co-author of the study, and an assistant professor in the Department of Civil, Environmental and Construction Engineering at the University of Central Florida said that knowing tidal changes lead to nuisance flooding gives us motivation to keep at a minimum, modifications made in sensitive estuarine systems. Doing so can help prevent exacerbation of nuisance floodings and other related potential problems.