TAMPA – Oct. 14, 2015 – The Miami area, including Fort Lauderdale and southern Broward County, is the nation’s fourth-most vulnerable region to the economic cost of storm surge in a 100-year hurricane, according to a recently released report.
A 100-year hurricane is one that has a 1 percent chance of occurring during any calendar year and a 10-percent chance of occurring within 10 years.
In the Miami area, that’s a Category 5 hurricane with top wind speeds of 165 mph, according to the report by Karen Clark & Co. a catastrophe modeling firm based in Boston. It said the tidal surge from such an event would have devastating consequences for the region, causing some $80 billion in damages. Wind damages were not measured in the report.
The study is the first based on probability and losses from an equally likely 100-year hurricane, the study’s authors said. Loss estimates were based on Karen Clark & Co.’s high-resolution coastal flooding model, which the company says was developed to allow private insurance companies to more accurately estimate levels of risk and sell more flood insurance.
As devastating as $80 billion in property damage might be for the Miami region, three cities would suffer more expensive losses in a 100-year storm.
And while four Florida cities are among the eight most vulnerable to storm surge flooding, the west coast of the state – with a shallower sea bed and more inlets – is more vulnerable than the east coast, the study said.
The Tampa region was ranked as the nation’s most vulnerable city, with estimated losses of $175 billion. One reason is that the wide and shallow continental shelf off Florida’s west coast would create higher sea levels. Another reason is that Tampa Bay would act as a large funnel when maximum winds moved into the mouth of the bay.
A severe storm with the right track orientation could cause an “enormous buildup of water that will become trapped in the bay and inundate large areas of Tampa and St. Petersburg,” the report said.
Half of the area’s population lives on ground less than 10 feet above sea level.
New Orleans, with half of the city at or below sea level, is the second-most vulnerable city, with estimated losses of $130 billion. Its low elevation and marshy terrain means storm surges can travel long distances before peaking, with additional flooding likely from Lake Ponchatrain as happened during Hurricane Katrina a decade ago.
With losses estimated at $100 million, New York City is third-most vulnerable. High surges would flow into Lower Manhattan, Staten Island and the south shore of Long Island, including Rockaway Beach and Islip.
Storm surge is less likely in the Miami region because the continental shelf falls off steeply off the coast, and there are few bays or other water features to create channeling, the report said. The area’s vulnerability stems from the high value of properties on low-elevation land near the coast. “It’s also one of the most likely areas for a direct hit from a severe Category 5 storm,” the report said.
Rounding out the report’s eight most vulnerable cities are Fort Myers (estimated loss: $70 billion), Galveston-Houston, Texas ($55 billion), Sarasota ($50 billion) and Charleston, S.C. ($45 billion).
Most of the loss potential for the eight cities is not currently insured, and private flood insurance has been difficult to obtain, primarily because loss potential has been difficult to assess, the report states.
The National Flood Insurance Program, which provides total coverage for most residential homes, caps coverage for businesses at $500,000 per building and $500,000 for a building’s contents. That leaves untold millions of dollars of coastal property value uninsured for flooding and many companies reluctant to offer policies because they have a tough time pricing the risk.
The authors say their high-resolution forecast model could help private flood insurers write more coverage.
Lynne McChristian, Florida representative for the Insurance Information Institute, an industry trade group, said in an email that different companies offer different models for predicting flood damage. Insurers price risk based on various models for the same reason weather forecasters rely on multiple hurricane tracking models.
More data means better risk modeling, and that gives insurers information they need to more accurately estimate flood insurance rates, and to better understand how much capital and reinsurance they would need to pay anticipated claims.
They need “some type of insurance that they will be allowed to charge a premium that accurately reflects the flood risk,” she said. “Without that, it would be very difficult for insurers to commit to a large private flood market.”
2015 the Sun Sentinel (Fort Lauderdale, Fla.), Ron Hurtibise. Distributed by Tribune Content Agency, LLC.