Eight of the top 10 U.S. cities that have seen an increase in “nuisance flooding” alongside rising seas are on the East Coast, according to a new report from the National Oceanic and Atmospheric Administration (NOAA).
Four of the top 10 cities are in the Chesapeake Bay watershed. Annapolis and Baltimore lead the list with a 925 and 920 percent increase in their average number of nuisance floods since 1960. Washington, D.C., has seen a 373 percent increase, while Norfolk has seen a 325 percent increase.
According to the report, nuisance flooding—or minor flooding that closes roads, overwhelms storm drains and compromises infrastructure never designed to withstand inundation or saltwater exposure—will worsen as sea level rise accelerates. Indeed, nuisance flooding has become “more noticeable and widespread” because of rising seas, sinking land and the loss of natural flood barriers.
“As relative sea level increases, it no longer takes a strong storm or a hurricane to cause flooding,” said William Sweet, oceanographer and lead author of the report, in a media release. “Flooding now occurs with high tides.”
Image courtesy rwillia533/Flickr
The study was conducted by scientists at the Center for Operational Oceanographic Products and Services, who compared data from 45 tide gauges with reports of nuisance floods; whether or not a nuisance flood has taken place is determined at the local level by a National Weather Service threshold. It is hoped the findings will “heighten awareness of a growing problem” and “encourage resiliency efforts in response to” sea level rise.
An understanding of where floods are occurring is integral to building climate resiliency. Once coastal communities know where environmental threats and vulnerabilities lie, they can take steps to move growth and development away from the coast, enhance preparedness efforts to protect human health and protect and restore wetlands, buffers and barrier islands that might shield the shoreline from strong wind and waves.
The Chesapeake Bay Program has set a goal to increase the climate resiliency of the watershed’s living resources and public infrastructure, using monitoring, assessment and adaptation to ensure the region withstands the impacts of a changing climate.