Storm Surge Experts Issue Warning on Outdated Modeling Systems

TAMPA, Fla. (June 2, 2009) USF Physical Oceanography Professor Robert Weisberg doesn’t know when a hurricane will make a direct hit on the Tampa Bay Region, but as an internationally renowned expert in storm surge he is certain that the system used to predict storm surge heights isn’t nearly as precise as it should be – and that leaves people and property at risk.

Weisberg has spent the past several years gathering evidence demonstrating that the current storm surge models used by the federal agencies are outdated and risk underestimating the deadly storm surge and flooding potential. The low-lying Tampa Bay region, the potential for storm surge destruction may be far greater than most residents realize or will be told should a storm bear down on the area, Weisberg said.

Weisberg – a member of the National Academies panel that studied the failed hurricane protection system after Hurricane Katrina – said while the technology for predicting storm surge has advanced in recent years, the modeling system used by NOAA is rooted in 1970s technology that doesn’t take into account new capabilities.

The current system, he contends, underestimates the reach of storm surge by some 30 percent.

The difference between the old modeling systems and the potential capabilities of new technologies can be as simple as this: the old system relies on two-dimensional modeling that tends to overestimate the friction by water rubbing against the gulf floor. The newer three-dimensional models more realistically account for bottom friction –creating a formula which Weisberg’s research shows is more accurate.

By overestimating bottom friction 2-D models underestimate storm surge height, and this may be remedied simply by using 3-D models.

Weisberg is part of a nationwide community of academics urging the National Oceanic and Atmospheric Administration; the Federal Emergency Management Agency and the Army Corps of Engineers to update their modeling systems. Weisberg, working with USF colleague Lianyuan Zheng, reported his findings on the capabilities of 3-D storm surge modeling in the December issue of the Journal of Geophysical Research.  Weisberg is also a member of a team of researchers from Florida and North Carolina investigating the workings of various models so that they may be improved.

“NOAA’s SLOSH (Sea, Lake and Overland Surges from Hurricanes) model was formulated in 1972; it was a state-of-the-art model,” Weisberg explained. “It’s now 2009 – we have a lot more capabilities now, it would make more sense that the model evolve too.”

The current models are not a complete disaster, Weisberg is cautious to note, they just are not as precise as if they employed the full range of technologies that have been developed in recent years.  The concern is that emergency managers, bound by law to use the NOAA models, compensate for their shortcomings by issuing broader evacuation orders while homeowners are still left vulnerable because they may forego insurance thinking their homes are not in danger of storm surge flooding.

For example, the newer models are able to account for storm surge not being of uniform heights as it inundates a coastline during a storm. A better model would have the capabilities of pinpointing very specific areas of danger.

The University of South Florida is one of the nation's top 63 public research universities and one of 39 community-engaged, four-year public universities as designated by the Carnegie Foundation for the Advancement of Teaching. USF was awarded more than $360 million in research contracts and grants in FY 2007/2008. The university offers 219 degree programs at the undergraduate, graduate, specialist and doctoral levels, including the doctor of medicine. The university has a $1.8 billion annual budget, an annual economic impact of $3.2 billion, and serves more than 46,000 students on institutions/campuses in Tampa, St. Petersburg, Sarasota-Manatee and Lakeland. USF is a member of the Big East Athletic Conference.

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