Sea Level Rise and Coastal Flooding

 

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Last week NOAA Released the 2022 update to the Sea Level Rise Technical Report. Sea level along the U.S. coastline is projected to rise, on average, 10 - 12 inches (0.25 - 0.30 meters) in the next 30 years (2020 - 2050), matching the rise measured over the last 100 years (1920 - 2020). Sea level rise will vary regionally along U.S. coasts because of changes in both land and ocean height. The east coast is expected to have the most significant rise in the next three decades projected to be, on average: 10 - 14 inches (0.25 - 0.35 meters).

The sea level rise hot spot along the east coast extends from Cape Hatteras, North Carolina to Boston, Massachusetts with the Southern Chesapeake Bay region will experiencing the most significant rise. In the last century this area experienced the highest rate of sea level rise in the nation and is forecast to continue to have the highest sea level rise in the next 30 years due to land subsidence on top of the rising sea levels.

Our local land subsidence is due to glacial rebound after the Laurentide ice sheet melted, excessive groundwater extraction from the coastal aquifers, as well as the effects of the meteor impact near Cape Charles, Virginia (about 35.5 million years ago). Combined, they are all causing the sea level rise. The Aquifer-system compaction from non-sustainable groundwater extraction accounts for more than 50% of the land subsidence observed in the coastal region. 

Virginia is experiencing tidal erosion and rising sea levels (or sinking land) along the 5,000 miles of tidal shoreline in Virginia. Nearly six million people, or 70% of the state’s population, call coastal Virginia home. Between rising sea levels and changing precipitation patterns, Virginia has already recorded changes to the frequency and intensity of floods that pose increasingly greater risks to our communities.

from NOAA

The NOAA report finds that by 2050, the expected relative sea level (RSL) will cause tide and storm surge heights to increase and will lead to a shift in coastal flood regimes, with major and moderate high tide flood events occurring as frequently as moderate and minor high tide flood events occur today. Without additional risk-reduction measures, Virginia coastal infrastructure, communities, and ecosystems will face significant consequences.

Wind events and seasonal high tides are already regularly flooding our Tidewater communities, and they will do so to an ever greater extent in the next few decades, affecting homes and businesses, overloading stormwater and wastewater systems, infiltrating coastal groundwater aquifers with saltwater, and stressing coastal wetlands and estuarine ecosystems.

NOAA states that regardless of the emissions pathway we will experience a higher regional sea level rise at 2050 than previously reported (Sweet et al., 2017). Flooding already affects many Virginians but does not do so equally. Each community faces varying levels of flood exposure, vulnerability to harm or damage, and associated risks, tied to its individual socioeconomic, historical, and physical context.

from NOAA whos says dry weather flooding is increasing