nuisance flooding
July 29, 2014

Nuisance Flooding An Increasing Problem Due To Rising Sea Levels

April Flowers for - Your Universe Online

The National Oceanic and Atmospheric Administration (NOAA) released a technical report on Monday revealing that of the top 10 US cities that have seen an increase in nuisance flooding, eight are on the East Coast.

Nuisance flooding causes public inconveniences such as frequent road closures, overwhelmed storm drains and compromised infrastructure, and is the result of rising sea levels. Such flooding has increased along all three US coasts between 300 and 925 percent since the 1960s.

Key findings of "Sea Level Rise and Nuisance Flood Frequency Changes around the United States" report include: the most increase in the number of flood days is tied between Annapolis and Baltimore, Maryland with more than 920 percent since 1960; on the Gulf Coast, Port Isobel, Texas has seen an increase of 547 percent in the same time period; and San Francisco, California has seen an increase of 364 percent.

The top ten list for nuisance flooding includes: Annapolis, Maryland; Baltimore, Maryland; Atlantic City, NJ; Philadelphia, PA; Sandy Hook, NJ; Port Isobel, TX; Charleston, SC; Washington, DC; San Francisco, CA; and Norfolk, VA.

"Achieving resilience requires understanding environmental threats and vulnerabilities to combat issues like sea level rise," said Holly Bamford, Ph.D., NOAA assistant administrator of the National Ocean Service. "The nuisance flood study provides the kind of actionable environmental intelligence that can guide coastal resilience efforts."

"As relative sea level increases, it no longer takes a strong storm or a hurricane to cause flooding," said William Sweet, Ph.D., oceanographer at NOAA's Center for Operational Oceanographic Products and Services (CO-OPS). "Flooding now occurs with high tides in many locations due to climate-related sea level rise, land subsidence and the loss of natural barriers. 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, probably more so than any other climate-change related factor."

CO-OPS researchers analyzed data collected from 45 NOAA water level gauges with long data records from around the country. This data was compared to reports of the number of days of nuisance flooding.

How extensive nuisance flooding becomes depends on various factors, including local topography and land cover. For the purpose of the study, the researchers defined nuisance flooding as a daily rise in water level above the minor flooding threshold set locally by NOAA's National Weather Service. They focused on coastal areas at or below these levels that are especially susceptible to flooding.

According to the team, the impacts of nuisance flooding will be further intensified by any acceleration in sea level rise. The rise in sea level will also reduce the time between flood events.

Coastal communities can use the data to assess flooding risk, develop strategies for mitigating and adapting to the effects of sea level rise, and improve coastal resiliency in the face of climate- and weather-induced changes.