The risk of flooding at high tide is accelerating, putting coastal economies at risk

Frequency of high tide flooding along US coasts has doubled since 2000

As sea levels rise, it can be easy to miss the subtlety of higher water. It is much more difficult to ignore the salt water which floods the streets more frequently, hinders daily life and worsens existing problems.

The frequency of high tide flooding along US coastlines has doubled since 2000 and is expected to increase five to 15 times over the next 30 years, the National Oceanic and Atmospheric Administration (NOAA) warns in a new report released. in July. 14, 2021.

I work with coastal communities in the northern Gulf of Mexico who face the risks of rising seas as they try to avoid avoidable damages and costs, such as infrastructure failures and falling value of properties. Information like the NOAA report is essential to help these communities succeed.

Last year, the United States experienced an average of four days of flooding at high tide, but that number doesn’t tell the whole story — regionally, several regions saw significantly more. There were a record number of high tide flood days in 2020 along the Gulf of Mexico and southeast Atlantic coasts. The city of Bay St. Louis, Mississippi went from three days of high tide flooding in 2000 to 22 days in 2020.

Flood days at high tide have multiplied. Renee Collini; NOAA High Tide Flood Outlook, CC BY-ND

NOAA’s annual high tide flood report predicts a national median of three to seven days of high tide flooding this year, again with regional differences expected. The western Gulf Coast, including Texas and Louisiana, is expected to experience the heaviest flood days, ranging from seven to 15 days. The northeast Atlantic is expected to experience six to 11 days of flooding at high tide. The Pacific Coast should be lower than other regions.

Calling it a “harmful” flood ignores the damage

Flooding at high tide impedes road use and increases wear and tear on stormwater and wastewater systems. The impact may seem minor, but as the frequency increases, those seemingly inconvenient flood days can have lasting effects.

Already, areas threatened by rising sea levels have seen declining property values, especially where cities and landlords have failed to take action to increase flood resilience. Insurance premiums are starting to rise to reflect real risk, and bond ratings are increasingly linked to community resilience efforts.

Flooded roads can create dangerous situations where first responders find it difficult to safely reach people in need. Businesses get fewer visitors and feel the loss of revenue depressed. The more often this happens, the more it affects coastal economies. It can affect tax revenues and erode community ties.

Illustration of two sources of sea level rise
Globally, sea levels have risen by about an eighth of an inch each year, and the rate is accelerating. It is caused both by the melting of land ice as global temperatures rise and by the thermal expansion of the oceans; the volume of water increases as it warms. Mississippi-Alabama Sea Grant Consortium, CC BY-ND

Sea level rise has a disproportionate impact on the poorest and most marginalized communities, and the impact of high tide flooding has been no exception. People living in some of the underserved coastal communities are facing increases in their insurance premiums due to flood and storm risks, sometimes with more than 90% of insurance policies in a single postcode which should increase.

Ways to reduce the threat of high tide flooding

NOAA’s projections provide valuable forecasts that can help local governments, landowners and other coastal stakeholders take action before the water level rises.

Communities can improve their infrastructure, such as raising roads and installing backflow preventers in stormwater systems, and modify building standards such as increasing freeboard, required distance between the first floor and the base flood stage, or designation of base flood elevations outside of current FEMA flood zones. to help prepare communities for higher seas. Communities can also work with nature to preserve and restore coastal habitats that provide natural flood protection, such as marshes and barrier islands.

Pensacola, Florida is an example of a proactive city. He recently completed a sea level rise vulnerability analysis to determine where high tide flooding will begin to strain infrastructure, low-income neighborhoods, economic hotspots and critical facilities. The city was able to recommend where to prioritize actions and what type of action will be needed to prevent high tide flooding from being costly or as damaging.

The message of the new report is clear: high tide flooding and other more severe types of flooding have already increased with rising sea levels and are expected to accelerate in coming years. Communities have the opportunity to act now to reduce impacts.

Residents of any coastal community can contact their local governments to encourage forward thinking. For more information on how to get involved in coastal resilience, almost every coastal and Great Lakes state has a Coastal Resilience Specialist within their Sea Grant programs. Each NOAA Regional Office for Coastal Management can also offer advice on how to get involved.

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Renee Collini, Coastal Climate Resilience Specialist, Mississippi State University

This article is republished from The conversation under Creative Commons license. Read the original article.

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