Sea Level Rise Driving Increase in Tidal Flooding

Flooding caused by high tides is often called “nuisance flooding”.  As sea levels rise, however, tidal floods are expected to become a more serious problem.

According to a report released this week by the Union of Concerned Scientists, coastal communities along this country’s East and Gulf coasts should expect to see a dramatic increase in tidal flooding over the next 30 years. Analyzing data from 52 tide gauges from Maine to Texas, researchers looked at how often communities flood now as compared to the past. They found that some areas have seen a fourfold increase in the annual number of flood days since 1970. Using a mid-range scenario of future sea level rise from the 2014 National Climate Assessment, the scientists forecast that, “more than half of the 52 communities can expect to average more than two dozen tidal floods per year by 2030.” Some areas, especially in the mid-Atlantic, can expect a tripling in the frequency of tidal flood events.

The report also states, “This flooding will define how and where people in affected areas live, work, and otherwise go about their daily lives.” Recognizing the need to adapt, the report offers “sensible steps for building resilient coastal communities.” These include upgrading infrastructure and developing both short and long-term plans to deal with sea level rise.

A tide that causes a minor flood today is a nuisance (white arrow). In the future, higher sea levels will allow high tides to push water deeper into coastal communities, affecting more homes, businesses, and infrastructure. Extensive moderate flooding—now usually associated with storms and high winds—is expected to become more common, simply from high tides.  Credit: UCS

Flooding – now usually associated with storms – is expected to become more common, simply from high tides.  Credit: UCS