By Madeline Urbish
Although some communities in the West will welcome the rain predicted to accompany El Niño forecasts for the next few months, coastal communities across the country are being warned that increased nuisance flooding will likely follow. A new report from the National Oceanic and Atmospheric Association (NOAA), predicts coastal communities in the Mid-Atlantic and West Coast may experience up to a 125 percent increase in the number of nuisance flooding days through April of next year. Specifically, the report states Sandy Hook, NJ, Lewes, DE, Washington, DC, and Norfolk, VA could see their greatest number of flood days on record, respectively.
Nuisance flooding is generally defined as flooding that causes public inconvenience, such as road closures, storm water overflows, and other issues that result in little to no property damage. In the study, NOAA looked at flood trends between 1950 and 2013 and discovered an acceleration of nuisance floods days between 300 and 925 percent since the 1960s, depending on the region. In 2014, the mid-Atlantic experienced significantly more nuisance flooding than the previous year, with 71 days in Wilmington, NC, 41 days in Annapolis, MD, and 33 days in Charleston, SC and Washington, DC.
The increase in tidal and nuisance flooding throughout coastal communities is largely attributable to rising sea-levels. According to NOAA, a more extreme weather event was required to cause nuisance flooding in 1950 when the average sea level was lower. Since that time, sea level rise has increased the reach of high tides, allowing weaker storms to result in real impacts, including overwhelmed storm water systems, flooding, and general infrastructure damage. Although nuisance flooding has increased across the board, the greatest changes can be seen in the mid-Atlantic region. This is in part due to the fact that sea level rise in the mid-Atlantic has been particularly pronounced over the past several decades. West Coast communities, in contrast, where sea level rise has been lower over the last couple of decades, experienced fewer nuisance flooding days in 2013.
That being said, more flooding occurred in both the mid-Atlantic and West Coast, as well as Honolulu, HI in 2014 than the previous year, and projections for the next several months are higher than expected from historical trends. “We know that nuisance flooding is happening more often because of rising sea levels, but it is important to recognize that weather and ocean patterns brought on by El Niño can compound this trend,” said William Sweet, Ph.D., an oceanographer at NOAA’s Center for Operational Oceanographic Products and Services (CO-OPS). The El Niño storm system is predicted to increase the number of flood days by as many as 62 days in Wilmington, NC and as few as 6 days in Montauk, NY; these numbers, though, constitute a 44 percent and 100 percent increase in expected flood days, respectively.
Flooding from increased sea levels and high tides can occur on sunny days and in non-coastal towns. In New Jersey, nuisance flooding affects areas surrounding the Passaic and Hackensack Rivers. “A lot of places along the Hackensack and Passaic [Rivers] are built at sea level, so a slight rise in sea level can have an impact. People have to pay attention,” said Alan F. Blumberg, an expert on storm surge at Stevens Institute of Technology. Last year, urban planners at the Massachusetts Institute of Technology were awarded $150 million in federal funding for a project to construct a series of berms around the Meadowlands region in New Jersey to protect it from chronic flooding. The project would build up to nine miles of earthen walls around areas that were devastated by the storm surge from Superstorm Sandy. “El Niño will go away,” said Blumberg. “But sea level rise is here for the long term.”
The “sunny day flooding” events are also becoming more common in the Norfolk, VA region. “We know it’s happening, so what are we going to do about it?” asked Ray Toll, director of coastal resilience at Old Dominion University. “We need a community action plan.” Toll is leading a two-year pilot project to develop a unified response to coastal flooding across local, state, and federal government agencies, including the military. Old Dominion is working with the State of Virginia to apply for funds through the Department of Housing and Urban Development’s National Disaster Resilience Competition grant program with The Rockefeller Foundation, also known as Rebuild by Design.
“As relative sea level increases, it no longer takes a strong storm or a hurricane to cause flooding,” said Sweet, the report’s lead author. Sweet also identified the simultaneous loss of natural barriers while sea levels rise as an important factor in the increasing number of nuisance flood days each year. “The effects of rising sea levels along most of the continental U.S. coastline are only going to become more noticeable and much more severe in the coming decades.”
NOAA’s report, Sea Level Rise and Nuisance Flood Frequency Changes around the United States, analyzes results from the study conducted by scientists at CO-OPS who looked at data from 45 water level gauges around the coast with long data records. The report concludes that any acceleration in sea level rise that is predicted for this century will continue to intensify nuisance flooding impacts. The report also includes information for coastal communities to help them assess their individual flooding risks, as well as develop mitigation and adaptation strategies. For more information on this report and others, visit www.noaa.gov.
For more information on this article, contact Madeline Urbish at firstname.lastname@example.org.