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There is some good news. Deep waters right off Miami Beach would likely absorb surging waters and limit on-shore surge to 10 feet, according to researchers at the hurricane center. But surge from shallow Biscayne Bay could top 18 feet south of there.
Storm surge, the most feared killer in a hurricane, should be much smaller in South Florida than it was in the Gulf.
Hurricane Katrina pushed a mountain of water more than 20 feet high ashore along parts of the Gulf Coast Aug. 29. Here, due to deep coastal waters off Broward and most of Miami-Dade, surging waters have someplace else to go instead of relentlessly forward onto land.
''Pure storm surge is likely not to exceed eight feet along the Broward coastline in even a Category 5,'' said Dr. Stephen Baig, chief of the storm surge research unit at the National Hurricane Center.
The bad news, Baig said, is the storm-whipped wave action that would occur on the temporary ocean that will rise rapidly in the coastal evacuation zones in both counties.
''For six to eight hours, you'll have wind-driven waves impacting structures that were never designed or intended to withstand such impacts,'' said Baig, who dislikes the commonly used ''wall of water'' metaphor for storm surge.
Broward is above sea level, so flooding here won't be nearly as bad as in New Orleans. Broward's flood maps indicate much of the county may be inundated in a hurricane, but water managers will lower canal levels in advance of a storm to accommodate more runoff. Who gets hit the hardest will depend largely on specific elevation and the angle of the hurricane if it makes landfall, officials say.
Unlike the levees in New Orleans, the levee system that separates the Everglades from the developed parts of the county is sound, according to officials with the South Florida Water Management District and the U.S. Army Corps of Engineers. Even if a breach were to occur, they say, water levels in western Broward and Miami-Dade would never become life-threatening because water levels there are too low.
Huge pumps also stand ready to remove excess water into the Everglades conservation zones.
Still, a hurricane that can drop 15 inches of rain in six hours, as Katrina did in some spots last month across South Florida, would overwhelm the system and leave low lying areas under perhaps three or four feet of water.
''I may get in trouble for saying this, but there are some places where they should never have allowed people to build,'' said Fred Remen, the water management district's director of field operations.
``There's no system that can get rid of water that quickly. In low-lying areas, you are going to flood.''
The 70-year-old, leaky 25-foot dike surrounding Lake Okeechobee could aggravate Broward's water woes. A serious breach would put thousands of nearby residents in places like Belle Glade in Palm Beach County in mortal danger. But in Broward, draining waters would only exacerbate flooding.
inotherwords wrote:Derek Ortt wrote:surge would be lower, but waves would be about 50 feet
Wow
Why is that? Because of the depth of the water offshore?
I wish I could see some sort of computer animation that would show what this would do. How far the water would come inland, what depth, etc.
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