Coastal flooding will soon be common in the U.S.

If sea levels continue to rise on the current trajectory, major coastal flooding events that are considered unusual today will soon become part of the normal routine. 

A new study published in Scientific Reports has found that extreme flooding events are set to double every five years across many coastal regions of the United States.

According to the researchers, the predicted pattern of sea-level rise has the potential to cause daily occurrences of 50-year water levels by the end of this century. 

A team of experts led by Mohsen Taherkhani of the University of Illinois at Chicago and Sean Vitousek of the USGS investigated how the frequency of major flooding events will increase in the coming decades.

To estimate the future rate of extreme water levels, the researchers combined sea-level rise scenarios with data from 202 tide gauges located in various regions across the United States coastline.

The researchers found that among 73 percent of the tide gauges, the difference between the daily average highest tide and the 50-year extreme water level was less than one meter. Most sea-level rise projections exceed one meter by 2100, especially under a high emissions scenario. 

The model developed in the current study predicted that by 2050, once-in-a-lifetime flooding events will happen annually across 70 percent of the U.S. coastline. By the year 2100, 50-year water level extremes will be exceeded on a near-daily basis for 93 percent of the sites measured.

The most susceptible areas will be low-latitude regions, where the rate of coastal flooding is set to double every five years. 

The most vulnerable sites, located along the Hawaiian and Caribbean coast, are expected to experience a doubled rate of extreme water levels with every centimeter of sea-level rise.

The study authors pointed out that the risk of coastal hazards associated with flooding, such as beach and cliff erosion, will accelerate alongside an increased risk of flooding.

The study is published in the journal Scientific Reports.

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By Chrissy Sexton, Earth.com Staff Writer