Though no city on the Texas coast has New Orleans' disadvantage of lying primarily below sea level, many of them rely for hurricane protection on levees whose adequacy has never been tested against a Katrina- or Rita-sized storm.
The industrial areas of the cities of Port Arthur, east of Houston, Texas City, on Galveston Bay, and Freeport, to the south, are guarded by levees designed to withstand a 14-foot surge. A Category 4 hurricane could have storm surges of 15 to 20 feet above the usual tide levels, the National Hurricane Center warns.
Galveston's 17-foot-high seawall, built after a catastrophic hurricane in 1900, was designed to withstand a surge of water from a major storm. But it doesn't protect two-thirds of the island, and beachfront homes and newer developments would be devastated if the storm strikes there, said James C. Gibeaut, a coastal geologist with the Bureau of Economic Geology at the University of Texas in Austin.
"It's totally unprotected," Gibeaut said.
Forecasters said Thursday that Rita appeared to be turning north, and they were projecting a possible landfall somewhere between Houston and the Texas-Louisiana coast, a trajectory that would spare Houston and Galveston a direct hit but would threaten Port Arthur, a city of 56,000 with numerous refineries and petrochemical plants.
Port Arthur's highest point is only 9 feet above sea level, but the city would be protected from much of Rita's surge not only by levees but also because it sits on the shores of Lake Sabine, a bay with only a narrow opening to the Gulf of Mexico.
Such a landfall also would affect Beaumont, a city of more than 110,000 that lies 17 miles inland.
A lingering storm also could dump enough rain on the region to cause major flooding, according to weather experts and emergency officials. The National Hurricane Center advised that rainfall from Rita could be as much as 25 inches in some areas.
Flooding from rain could be a bigger threat in Houston than the kind of tidal surge that was so destructive along Mississippi and Louisiana's coastline, said Billy Edge, a professor of coastal engineering at Texas A&M University.
Edge noted that Houston is largely protected from a big storm surge by barrier islands that stretch across Galveston Bay. But rain would collect in low areas of the city—though it would recede relatively quickly, rather than remain for weeks as it did in New Orleans.
In general, Army Corps of Engineers officials expressed optimism about the condition of Texas' levees and seawalls. A corps spokeswoman said a team of engineers from Texas A&M University had inspected the levee at Freeport only two years ago and found it capable of withstanding large storms.
Still, the levees have never faced anything the size of Rita. "These have been built for several years, but have never been tested with a storm as big as this one is anticipated to be," said Marilyn Uhrich, a public affairs officer for the Army Corps of Engineers in Galveston.
Engineers remained worried about flooding along the western shore of Galveston Bay, said Gus Marinos, the corps' emergency manager in Galveston. Of particular concern was the Clearlake area and the upper Houston Ship Channel. Texas City, which is protected by a hurricane flood-protection project, could be swamped by water running around its levees from a Category 4 hurricane, he said.
"We're not anticipating flooding from a smaller event," Marinos said.
———
(Carey reports for the San Jose Mercury News.)
———
(c) 2005, Knight Ridder/Tribune Information Services.
Need to map
Comments