in just a matter of hours
SO i live in Houston Tx, Hurricane alley–seems like we get something all the time depressions, storms or hurricanes…Look at this report from the gov on what would happen if a cat 5 hit here.
This from the Houston Chronicle.
Can city weather bigger storms? / Scenarios of a fate worse than last year’s devastating Allison leave Harris County planners and other officials concerned about Houston.
By ERIC BERGER, Houston Chronicle Science Writer
Staff
Harris County planners call the doomsday storm Hurricane Cody; the U.S. Army Corps of Engineers prefers Jackson.
By any name, a major hurricane striking Houston today would have devastating consequences - hundreds to thousands dead, damage in the tens of billions of dollars and perhaps as many as 1 million left homeless, to say nothing of dismal long-term economics.
A year after the devastation of Tropical Storm Allison, residents along the Texas Gulf Coast likely realize how vulnerable they remain to tropical weather. But as the 2002 hurricane season begins this weekend, local planners agree that things could be far worse than last year.
Allison packed just one-third of a major hurricane’s triple wallop; it had lots of rain, but lacked the storm surge and tornadic winds. The strongest hurricane, a Category 5 storm, has winds above 155 mph.
Such a storm has only about a 3 percent chance of striking the Gulf Coast in any given year.
“I know the (Texas) Medical Center and people here on the Rice campus have been concerned about preparing for what happened before with Allison, if it happens again,” said Arthur Few, a Rice University professor of physics and astronomy.
“But I’m not sure they have tried to anticipate what might happen if something worse hit. I doubt we’re ready for whatever a big hurricane could throw at us.”
Shortly after Hurricane Mitch struck Central America in 1998, Harris County Judge Robert Eckels asked planners what would happen if such a storm hit Houston.
Then, last year, the U.S. Army Corps of Engineers studied the type of federal response needed to a hurricane almost as powerful as Mitch.
Both studies left planners with plenty of reason for sleepless nights.
In Harris County’s scenario, Cody caused $18 billion to $36 billion in property damage, with only one-quarter due to inland flooding, which has caused nearly all the problems in Houston’s recent storms, including Allison.
Damages from a Category 5 storm surge, a dome of water perhaps 50 miles wide and 30 feet high, exceeded $10 billion in Cody. It swamped Johnson Space Center. Interstate 45 at Clear Creek was under 15 feet of water. Such a storm surge would almost certainly conquer Galveston’s 17-foot seawall.
In the end, the projection suggests, the surge would cover nearly a fourth of Harris County, including much of Clear Lake and Pasadena. About 700,000 people live in those areas, and it would take 30 hours to evacuate.
As 10 percent of people traditionally don’t heed evacuation warnings, and of those left behind 10 percent die in a major storm surge, the math reveals a grisly death total of 7,000.
“The results of the study are not pretty,” Eckels said.
Another problem - unlike Allison, when nearly all clogged freeways and overflowing bayous cleared within half a day of the heaviest rain - is that a storm surge would block waterways from draining into Galveston Bay for a day or more. Those under water would remain wet a good deal longer, and transportation woes would be compounded over days, not hours.
Gusting winds and tornadoes birthed along the storm’s front would be no more merciful.
An additional $5 billion to $17 billion of damages in the Cody scenario were attributable to wind damage from sustained winds above 170 mph and gusts exceeding 200 mph, just a bit slower than the tornadoes that struck Oklahoma City in 1999. And the wind would last for hours, not minutes.
Power poles would snap like toothpicks. Crews would not have access to downed lines in the storm’s aftermath, as tree limbs would close roads long after floodwaters receded. Homes not flooded would be threatened from above by roof-scalping gusts. Windows from downtown skyscrapers would pop out, becoming deadly missiles to anyone stranded on streets below.
Long-term consequences are difficult to imagine, but there likely would be massive infrastructure loss, an economic base destroyed and permanent property value depreciation, all at a time when the government would need more money than ever.
If all this sounds bad, it is. But could it really happen?
Only two Category 5 storms have struck the United States in the hundred-plus years such data has been kept: Camille in 1969 and a 1935 Florida Keys storm.
But it has nearly happened twice here since 1900, with the Great Storm that year that hit Galveston, and a follow-up in 1915. Both storms were later classified as Category 4 storms, one step below a Category 5. If they hit today, experts say, each would cause $20 billion to $30 billion in damage.
The Corps of Engineers scenario of Hurricane Jackson envisions a Category 4 storm coming ashore directly over Houston and Galveston, taking 103 lives and causing $15 billion in property damage.
Attempting to respond to such a storm would prove nearly overwhelming, the corps study found.
More than 2.6 million people in Harris and surrounding counties would be left at least temporarily homeless under the Jackson scenario. A month later, one-quarter of the impacted area would remain without power. During the initial response to the storm, 60,000 gallons of water and 350,000 pounds of ice would have to be brought into the area daily.
With Jackson, Harris County would be left with 8.4 million cubic yards of debris - more than 10 times the amount Allison left behind in Houston and considerably more trash than the city has collected in the past decade.
The last storm of this magnitude to hit Houston was Hurricane Carla, which struck in 1961, when the county’s population was about one-third of what it is today. That storm came ashore near Port Lavaca.
In terms of flooding, some scientists and forecasters say, Allison may be about as bad as it gets.
A hurricane would be less damaging, floodwise, because it would move through the area more quickly, they say. Allison, with nothing pushing it and barely reaching tropical-storm status, lingered for a week and had saturated the ground before its final flurry of rainfall.
Yet another Rice professor, Phil Bedient, says other storms could well wet the ground before a big hurricane, and that Allison’s most problematic rain came within a four-hour window, less time than even a fast-moving hurricane would spend in the area.
“In Houston and Galveston, we really haven’t been hit as hard as we could be,” Bedient said.
Is the Houston area as ready as it can be?
Just as New Orleans cannot change its below-sea-level city center, Galveston cannot change its coastal perch and Houston can’t change its flat topography with few safe areas. Only so much can be done.
Following Carla’s strike, Galveston added large chunks of granite rubble, or riprap, along the seawall.
“That would help break up the biggest waves,” said Charles Dalton, a University of Houston professor of mechanical engineering.
It has passed the test so far, but the greatest challenge since Carla was Hurricane Alicia in 1983, a Category 3 storm.
Since its study, Harris County has taken steps such as having contingency contracts with out-of-area contractors to help remove debris immediately after a storm. The county may also petition the Texas Legislature to mandate metal straps to tie down roofs in new homes. New software in the county’s Office of Emergency Management can better predict flood areas in a major storm, giving residents more time and more accurate warnings.
The key, Eckels said, is having people heed those evacuation warnings.
“We’re not going to tell people to leave their homes for no reason,” he said. “If they stay behind, they’re going to see something of a scale that is almost unimaginable.”
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Harris County storm surge
A storm surge occurs when the winds swirling around a tropical system push water toward the shore. Because these walls of water can exceed 24 feet in the biggest systems, storm surges have historically accounted for nine of 10 deaths during hurricanes.
Estimated area of the county that a storm surge would swamp
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Storm season
Hurricane season began Saturday and continues through Nov. 30. The official forecast calls for a slightly more active than normal season, with nine to 13 named storms, including two or three major hurricanes.