New Jersey and Delaware face some of the highest risks in the nation for flooded properties over the next 30 years, driven by an increasingly northern reach of hurricanes due to rising temperatures in the atmosphere and oceans, a nonprofit research group focusing on flood risks says.

For New Jersey, it says, that includes tens of thousands more properties at risk by 2050 than federal data currently suggest.

First Street Foundation’s first National Flood Risk Assessment, released Monday, was compiled by scientists who say they developed a “high-precision, climate-adjusted” online Flood Factor tool for property owners. The tool ranks properties on a scale of 1 to 10 based on a risk of flooding over the next 30 years and allows people to assess the risk for 142 million properties in the United States.

The accompanying report looked at current flood risks, then assessed risks for 2050. .

The Federal Emergency Management Agency (FEMA) currently classifies 8.7 million properties as having substantial risk within “Special Flood Hazard Areas” based on past and present flood risk. First Street Foundation’s modeling identified 14.6 million properties with that risk, nearly 6 million more. However, in the First Street model, some states have fewer properties at risk than FEMA data show.

Flood insurance rates are set using FEMA data.

The top five states showing the greatest proportion of properties with substantial flood risk — meaning a bigger percentage of a community is exposed to risk — are West Virginia, Louisiana, Florida, Idaho, and Montana. The authors found that flood risk is changing for not only coastal states, but inland states too because of shifting patterns of precipitation.

By 2050, the number of U.S. properties facing substantial risk will increase by 10.9% to 16.2 million because of climate change and sea level rise, the researchers found.

By then, Louisiana, Delaware, New Jersey, Florida, and South Carolina are projected to rank highest for proportional increase of properties with significant flood risk. The risk for Philadelphia and other Pennsylvania municipalities also rises substantially.

Currently, First Street data show New Jersey has 8,100 fewer properties at substantial risk than FEMA data calculate. But First Street projects that 73,600 more New Jersey properties will be at substantial risk by 2050.

In total, First Street’s Flood Model suggests 617,300 properties in New Jersey are at risk over the next 30 years.

“Sea level rise is exposing an increasing number of coastal properties to flooding from extreme high tides and storms,” said Robert Kopp, director of the Rutgers Institute of Earth, Ocean, and Atmospheric Sciences. Rutgers led the development of the sea level rise projections used in the analysis.

The report says Ocean City, N.J., currently has 81% of its properties at risk of flooding. By 2050, that’s expected to rise to 94%.

From a First Street Foundation flood modeling released in a June 29 report.
First Street Foundation
From a First Street Foundation flood modeling released in a June 29 report.

Doug Bergen, a spokesperson for Ocean City, said in a statement that the numbers reflect that the community happens to have more properties than any other Shore town. He note that current FEMA maps show greater risk than First Street data.

“Flood remediation is a very important issue in Ocean City,” Bergen said. “The city has worked with partners at the federal and state levels on a number of fronts. An uninterrupted dune system and replenished beaches now protect our entire oceanfront, thanks to Army Corps of Engineers projects, including one that is scheduled to begin on July 6.”

Bergen also noted that ordinances require all new and substantially renovated homes to be elevated and that Ocean City is dedicating $100 million over the next five years for elevated streets, upgraded drainage, and pumping stations, among other measures.

“This is all part of a comprehensive strategy that Ocean City has adopted to address flooding issues,” he said.

Some Shore communities smaller than Ocean City show a greater proportion of property at risk. For example, the First Street data show 98% of Wildwood’s properties now at risk, rising to 99% in coming decades.

From a First Street Foundation report saying it had found nearly 6 million more properties at risk of flooding than the Federal Emergency Management Agency's flood maps indicate because it takes into not only past and present flood risk, but future risk because of climate change and sea level rise.
First Street Foundation
From a First Street Foundation report saying it had found nearly 6 million more properties at risk of flooding than the Federal Emergency Management Agency's flood maps indicate because it takes into not only past and present flood risk, but future risk because of climate change and sea level rise.

In Pennsylvania, the report says, Philadelphia has the greatest number of properties at risk of flooding, with 53,400 currently at risk, or 10% of its total properties. But smaller municipalities might have a greater proportion of total properties at risk. For example, Folcroft, Delaware County, bordered by Darby Creek, will experience a 56% increase in properties at risk over the next 30 years, the report states.

The modeling was conducted by researchers and hydrologists from First Street, including scientists from Columbia, George Mason, and Rutgers Universities; the Massachusetts Institute of Technology; the University of California, Berkeley; and the University of Bristol in England.