Miami Herald: South Florida leads the nation in potential storm-surge losses
Apr 4, 2010
The potential dollar losses from storm surge in heavily developed Southeast Florida are bigger than in any other metro area in the nation, according to a new ZIP-Code analysis produced by a private risk-assessment company.
The study projects that a Category 5 hurricane could expose more than a quarter million homes in the tri-county region worth $53.6 billion to flood damage, topping Virginia Beach’s $39.5 billion, and that even a minimal Category 1 storm could expose 55,000-plus homes worth nearly $20 billion to surge flooding.
Two other Florida cities — Jacksonville and Tampa — ranked No. 3 and No. 7 in the analysis of 13 communities on the Gulf and Atlantic coasts by First American Corp., which assesses real estate risks for mortgage lenders and insurers. New Orleans, flooded by Hurricane Katrina in 2005, ranked only No. 6.
The list shouldn’t be confused with a simple ranking of areas most vulnerable to the effects of storm surge.
`Really what this is focusing on is what is the potential dollar loss,” said Howard Botts, vice president of database development for the company, which is based in Austin.
That’s why low-lying but lightly populated islands of the Florida Keys, for instance, weren’t assessed though storm-surge experts consider them clearly at the top of high-risk zones.
Instead the company chose coastal areas with a combination of high density, high property values and high risk of hurricane strikes. It also plugged in worst-case conditions — storms at maximum wind speeds for each category, arriving at high tide, with the strongest right front quarter making landfall.
The Miami metro area, which the study defined as a stretch from South Miami-Dade to Jupiter dotted with multimillion-dollar waterfront mansions on canals, ranked at the top of the list — as it has in previous risk-assessment studies by other companies and researchers.
“From the property value standpoint, it’s very hard to find a place that rivals South Florida,” said Stephen Leatherman, director of Florida International University’s International Hurricane Research Center.
While Southeast Florida is a frequent hurricane target, he said, a shoreline that steeply slopes into deep ocean helps limit the height of surges — at least from Miami Beach northward.
“Off the beach, it drops pretty quickly and a mile or so offshore, it can be a hundred feet deep,” he said. “Because of that, even with a direct hit, you’re not going to get that much of a huge storm surge.”
Along the Gulf Coast, the wide and shallow continental shelf allows surge water to stack up and push deep inland. Hurricane Ike pushed waters 12 miles inland in the Panhandle. And Hurricane Katrina’s surge, which breached the levees surrounding New Orleans, was actually higher in Mississippi, hitting 27 feet and wiping out coastal homes.
By contrast, Hurricane Andrew, a small but intensely powerful Category 5 storm, generated a surge that topped out at 17 feet near the Deering Estate, where shallow Biscayne Bay helped raise surge levels. The impacts to Miami Beach were minimal.
That’s not to suggest South Florida — always a primary target during hurricane season — should ever shrug off surge threats.
SERIOUS THREAT A surge doesn’t have to be two stories high to threaten lives and properties in South Florida, said Jamie Rhome, who heads the storm-surge unit at the National Hurricane Center in Miami. “Once you start getting above five or six feet, it’s all extreme to me,” Rhome said. “That’s the point you start drowning.”
Though not every storm that has hit South Florida has produced killer surge, when they’re bad, they can be very very bad.
The unnamed category four hurricane that hit Miami and Miami Beach in 1926, for example, was ranked as the most damaging ever in a 2008 study by Christopher Landsea of the National Hurricane Center and Roger Pielke Jr. of the University of Colorado. The inflation adjusted loss: $157 billion, much of that from massive flooding. Losses from Katrina are estimated at $80 billion.
For its analysis, First American overlaid surge model maps with its extensive real estate data base to calculate exposure, parcel by parcel. The study identified 10 ZIP Codes in South Florida with the most property value at risk — with some surprising results.
While homes close to the coast are typically considered most vulnerable, the analysis underlined that rivers and inland waterways and other factors can add to surge threats.
In Broward, for instance, the top-ranked ZIP Codes — 33301 and 33308 — include mansions along the New River and canals of Las Olas Isles and more densely populated Lauderdale-by-the-Sea.
In Miami-Dade, however, Pinecrest and the more modest but also numerous homes of Palmetto Bay and Cutler Bay in ZIP Codes 33317 and 33156 ranked high — primarily because of the proximity to shallow Biscayne Bay. The Miami Beach ZIP Code of 33140 includes Indian Creek and some of the county’s most expensive homes.
David Rogers, vice president of market for First American, said the message for most homeowners should be to buy federal flood insurance, which covers surge losses. There have been legal battles over the limits of hurricane insurance, with private insurers arguing they shouldn’t pay damages caused by storm surges.
NOT NEW ORLEANS Unlike New Orleans, which sits below sea level, South Florida wouldn’t fill up like a swimming pool from surge, said FIU’s Leatherman. “We’re not going to have that kind of damage,” he said. “It seems obvious but so many people ask me that question.”
But a strong surge still could undermine foundations, blow out walls and flood streets before draining off and leaving behind a stinking mess that could easily run into tens of billions. Because so many factors — from the size, speed and angle of the storm to tidal phases at landfall — play into surge impacts, homeowners who have weathered a storm too often dismiss the threat, said Rhome.
“That’s one of the things that trip people up the most,” he said. “They think they went through a Category 1 storm five years and they weren’t flooded so they won’t be flooded again. That kind of thinking is absolutely wrong.”
Find this article at: http://www.miamiherald.com/2010/04/04/v-fullstory/1563421/south-florida-leads-nation-in.html