Changing sea levels causing ‘significant water resource problems,’ flood risk on U.S. northeast coast: Army Corps of Engineers

The United States Army Corps of Engineers warned Wednesday of flood risk posed by changing sea levels and the importance of land use planning and identified “high risk” areas such as the cities of Baltimore and Washington, D.C. 

The Corp of Engineers announced Wednesday it released its North Atlantic Coast Comprehensive Study (NACCS), which provides a “Coastal Storm Risk Management Framework that can be used by communities, states, tribes, and the Federal government to help identify coastal risk and develop strategies for reducing those risks.”

The study was authorized by the U.S. Congress, in January 2013, in the Disaster Relief Appropriations Act of 2013, about two months after Hurricane Sandy.

“Hurricane Sandy made us acutely aware of our vulnerability to coastal storms and the potential for future, more devastating events due to changing sea levels and climate change,” the Corps of Engineers stated.

In 2013, Aon Benfield estimated Hurricane Sandy caused economic losses of US$72 billion and insured losses of about US$30 billion. The storm was downgraded to post-tropical storm status when it made landfall about 200 kilometres south of New York City on Oct. 29, 2012.

“One of the important data gaps identified by the NACCS is how sea level change will affect communities and their existing stormwater infrastructure,” the Corps of Engineers noted Wednesday. “Sea level change will alter the ability of streams and rivers to convey rainfall to coastal bays and estuaries and may increase the frequency and severity of inland and coastal flooding from rainfall.”

Aon Benfield reported in 2013 that water inundation heights in the New York City area approached 10 feet.

“Changing sea levels represent an inexorable process causing numerous, significant water resource problems,” the U.S. Army Corps of Engineers said in its NACCS. Those problems include increased, widespread flooding along the coast, increased inundation at high tide and decreased capacity for stormwater drainage.

The study included several findings, outcomes and opportunities, such as “the importance of land use planning, wise use of floodplains, and strategic retreat as cost-effective risk management tactics; the value in considering the full array of risk reduction measures (e.g., nonstructural, structural, natural and nature-based, and programmatic) in project planning and combining measures, where appropriate; the need for greater institutional alignment and financing; better use of pre-storm planning and post-storm monitoring tools; and better education on flood risk and the availability of flood risk management solutions,” the Corps of Engineers stated in a press release.

It also identified nine “high-risk areas on the U.S. northeast coast that “warrant additional analysis.” Those include the cities of Baltimore, Norfolk, Va. and Washington, D.C., as well as trhe New York-New Jersey Harbor and tributaries. Other high risk areas are: the coastlines of the states of Rhode Island and Connecticut; Nassau County Back Bays, New York; New Jersey Back Bays; Delaware Inland Bays and Delaware Bay Coast.

“Hurricane Sandy brought to light the reality that coastal storms are intensifying and that sea-level change and climate change will only heighten the vulnerability of coastal communities,” stated Brigadier General Kent D. Savre, commanding general of the U.S. Army Corps of Engineers North Atlantic Division, in a release. “Coastal storm risk management is a shared responsibility, and we believe there should be shared tools used by all decision makers to assess risk and identify solutions. This report provides those tools.”

 PHOTO: The United States Army Corps of Engineers oversees debris operations in New York after Hurricane Sandy. Photo courtesy of the Corps of Engineers.