Coastal infrastructureAs sea level rises, coastal communities brace for more frequent, destructive tidal flooding
Today, many coastal communities are seeing more frequent flooding during high tides. As sea level rises higher over the next fifteen to thirty years, tidal flooding is expected to occur more often, cause more disruption, and even render some areas unusable — all within the time frame of a typical home mortgage. An analysis of fifty-two tide gauges in communities stretching from Portland, Maine to Freeport, Texas shows that most of these communities will experience a steep increase in the number and severity of tidal flooding events over the coming decades, with significant implications for property, infrastructure, and daily life in affected areas. The report warns that given the substantial and nearly ubiquitous rise in the frequency of floods at these fifty-two locations, many other communities along the East and Gulf Coasts will need to brace for similar changes.
Today scores of coastal communities are seeing more frequent flooding during high tides. As sea level rises higher over the next fifteen to thirty years, tidal flooding is expected to occur more often, cause more disruption, and even render some areas unusable — all within the time frame of a typical home mortgage.
An analysis by the Union of Concerned Scientists (UCS) of fifty-two tide gauges in communities stretching from Portland, Maine to Freeport, Texas shows that most of these communities will experience a steep increase in the number and severity of tidal flooding events over the coming decades, with significant implications for property, infrastructure, and daily life in affected areas.
A UCS release warns that given the substantial and nearly ubiquitous rise in the frequency of floods at these fifty-two locations, many other communities along the East and Gulf Coasts will need to brace for similar changes.
A daily cycle gains disruptive force
Twice each month (during new and full moons), the combined gravitational pull of the sun and moon creates tides that rise slightly higher than normal.
In some coastal communities, these extreme tides, or spring tides, flood low-lying areas. In many locations, these floods are happening much more often than just forty years ago. In several communities, tidal flooding has quadrupled in frequency since 1970.
Today most tidal flooding events are minor, disrupting local transportation and daily life for brief periods of time. More extensive moderate flooding does occur in some locations from tides alone, but infrequently. Strong winds, rainfall, and storms that coincide with high tides can result in even more extensive and damaging floods.
Sea level rise, driven primarily by global warming, is the main cause of observed increases in tidal flooding. While global sea level rose roughly eight inches from 1880 to 2009, much higher rates have occurred along parts of the East Coast, including New York City (more than seventeen inches since 1856), Baltimore (thirteen inches since 1902), and Boston (nearly ten inches since 1921).
Tidal flooding in 2030: From occasional to chronic in fifteen years
The report says that by 2030, more than half of the fifty communities studied are projected to experience, on average, at least twenty-four tidal floods per year in exposed areas, assuming moderate sea level rise projections. Twenty of these communities could see a tripling or more in tidal flooding events.
