Report analyzes new choice for whirly protection

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Past discussions of hurricane-protection options for a Houston-Galveston segment have focused on constructing a floodgate during a mouth of presumably Galveston Bay or a Houston Ship Channel. In a latest investigate of options that federal, state and internal officials competence consider, Rice University experts offer a third alternative: a mid-bay embankment median between a formerly discussed sites.

Image credit: Rice University's SSPEED Cente

Image credit: Rice University’s SSPEED Cente

In a new report, Rice’s Severe Storm Prediction, Education and Evacuation from Disasters (SSPEED) Center describes how a mid-bay choice could yield storm-surge word for a heavily populated communities on a west side of Galveston Bay as good as for a industrial formidable along a Houston Ship Channel. The news also sum how a mid-bay embankment could be partial of a endless informal flood-reduction devise if it were total with components of a “Ike Dike” like new levees, dikes and towering roadways.

SSPEED’s latest investigate is partial of an ongoing bid to emanate a Houston-Galveston Area Protection System, or H-GAPS, a endless and well-documented set of options that policymakers can cruise in building a informal hurricane-protection plan. SSPEED is coordinating a investigate with ongoing efforts during Texas AM University during Galveston, a U.S. Army Corps of Engineers and others.

The H-GAPS mid-bay choice calls for constructing a floodgate opposite a vessel channel nearby San Leon. The gate, that would be sealed to reason behind charge swell from an coming hurricane, would be tied into an endless network of synthetic reefs and island berms — many of that already exist — that would dissect a brook in both north-south and east-west directions.

SSPEED officials contend mechanism simulations have shown that a mid-bay choice would significantly revoke storm-surge flooding in both a Houston Ship Channel and in a heavily populated west Galveston Bay communities that are formidable to evacuate.

“The mid-bay embankment devise is designed to revoke charge swell in a vessel channel’s industrial formidable as good as in west brook communities like Clear Lake, Kemah, Bayview and Seabrook,” pronounced SSPEED Director Phil Bedient, Rice’s Herman Brown Professor of Engineering. “The former represents a many poignant mercantile and environmental hazard from a whirly and a latter represents a many poignant hazard to tellurian life.”

SSPEED initial began investigate informal whirly word in a arise of Hurricane Ike in 2008. The sprawling 600-mile-wide Category 2 charge struck Bolivar Peninsula northeast of Galveston on Sept. 13, 2008, causing $29.5 billion in damages, many of it due to swell flooding. SSPEED’s investigate relies on worldly simulations grown by researchers during a University of Texas during Austin. The simulations, that run on UT supercomputers, concede SSPEED to reconstruct chronological storms like 2008′s Ike and 1961′s Carla, immigrate them anywhere along a seashore and observe a storm-surge flooding that would occur, not usually during a seashore though also within a brook and in a vessel channel’s industrial complex. The models also concede a researchers to exam how good any multiple of dikes, levees, seawalls and storm-surge barriers would revoke flooding in any of a charge scenarios.

Of a many scenarios SSPEED has studied, a one that many closely resembles a Federal Emergency Management Agency’s (FEMA) benchmark 100-year storm-surge flooding eventuality for Galveston Island is a charge with breeze speeds 15 percent stronger than Ike’s that creates landfall southwest of Galveston nearby Freeport. Such a charge would be a Category 3 hurricane, and SSPEED’s simulations uncover a storm’s swell would go over a Galveston Seawall, swamp a Houston Ship Channel with about 25 feet of seawater and inundate hundreds of retard miles of densely populated suburbs along west Galveston Bay.

“For those who trust this unfolding is far-fetched, we would indicate out that some-more than 100 Category 3 hurricanes have done landfall on a coastlines of a Gulf of Mexico given 1900,” pronounced SSPEED Co-director Jim Blackburn, highbrow in a use of polite and environmental engineering during Rice. “If we demeanour closer to home, annals uncover that a charge of this power strikes a top Texas seashore roughly any 25 years. It is not a matter of if such a charge will strike, though usually when and where.”

SSPEED’s latest investigate is a initial partial of a three-year investigate saved by Houston Endowment to yield recommendations to a state of Texas, a Corps of Engineers and other sovereign agencies on a best approach to strengthen life, attention and a sourroundings from large, potentially harmful hurricanes.

In further to a categorical embankment over a vessel channel, a mid-bay embankment offer calls for smaller gates that would fill a space between existent dredged containment berms that run from north to south along a top bay. Some of these already mount 25 feet high and tie into high belligerent to a north nearby Cedar Bayou and to a south during a Texas City levee. These existent containment sites are done from a lees collected from dredging a Houston Ship Channel.

“This unfolding utilizes a berms that are being filled with dredged element from a Houston Ship Channel,” Blackburn said. “It also presents opportunities for nonstructural improvements, such as formulating oyster reefs underneath a H2O aspect of a berms, mire areas adjacent to a berms or rookery medium on a filled islands. This unfolding will also embody periodic openings for normal vessel trade and environmental flows between a enclosed islands with a embankment structure to retard a upsurge of H2O by a complement during a storm. And this resolution is positively concordant with a dual landscape-scale, nonstructural alternatives — a Texas Coastal Exchange and a Lone Star Coastal National Recreation Area — also recognised by a SSPEED Center.”

In further to a mid-bay embankment complex, a H-GAPS mid-bay informal word devise calls for formulating a “coastal spine” by regulating and presumably lifting a tallness of Galveston’s ancestral seawall, lifting Farm-to-Market Road 3005 along west Galveston Island and lifting Texas Highway 87 along Bolivar Peninsula. The devise also calls for lifting portions of a Texas City levee, and formulating a new wharf to forestall backside flooding of Galveston from brook floodwaters.

To ready their report, SSPEED researchers used a latest FEMA inundate maps and recently updated word attention assessments that call for 19- to 20-foot storm-surge word for poignant portions of a Houston Ship Channel industrial complex.

In further to building and evaluating a cost and opening of a mid-bay embankment option, Bedient pronounced SSPEED also evaluated options for upper-bay and lower-bay embankment options. He pronounced SSPEED and a other investigate collaborators are also evaluating other concepts.

The upper-bay embankment and mid-bay embankment strategies would cost about $2.8 billion each, while a lower-bay gate’s rough cost guess is around $7.6 billion.

“Our studies over a past 8 years have found there is no one-size-fits-all resolution to strengthen a Houston-Galveston segment from a subsequent vast hurricane,” Bedient said. “One thing that is transparent from any unfolding we have tested is that a floodgate contingency be built somewhere opposite a vessel channel in sequence to meaningfully revoke a risk of inauspicious flooding in a industrialized apportionment of a vessel channel.

“The vast embankment structure is a singular many costly object in any informal word plan, and a over south we pierce a gate, a some-more costly it is to build,” Bedient said. “The purpose of looking during any plcae is to establish what a advantages and costs are during any site so that policymakers will have a transparent design of how they can maximize a flood-reducing advantages for any dollar they spend.”

Source: Rice University