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In September 2008, Hurricane Ike made landfall near Galveston, Texas, as a Category 4 storm with a 20-foot storm surge. Although the hurricane caused over $7 billion in damages, it soon became apparent that the disaster It could have been much worse: If the storm hit the coast at a different angle, the waters might have swept through the Houston Ship Channel and flooded the city. A very important petrochemical centerNot to mention thousands of homes.
In the aftermath of the storm, Texan officials searched for a way to protect Houston from similar events in the future, and quickly settled on an ambitious project that became known as “Ike Dike”—a series of seawalls and artificial sand dunes along 50 miles of Galveston Bay, anchored by a concrete gateway. Two miles wide at the mouth of the ship canal. The gate would remain open during calm weather to allow ships to enter and exit the canal, but would close during hurricanes, protecting the city and oil infrastructure from flood events.
Ike Dike has since become synonymous with hurricane resilience in Houston: Local officials have spent a decade lobbying for the project, and now it’s closer than ever to becoming a reality. US Army Corps of Engineers, the nation’s largest builder of dams and flood walls, Obtaining congressional approval To advance the construction of the barrier last year. The $31 billion system is the largest project the Corps has ever undertaken, with the Gateway system accounting for two-thirds of the cost. The agency says it will It takes about two decades to complete.
Despite the project’s sheer scale, there’s one big problem: Experts say Ike Dike won’t reliably protect Houston from major storms. The barriers may not actually be tall or strong enough to handle severe storms, especially as climate change makes the rapid intensification of hurricanes more likely. And even if the barrier holds, it won’t do anything to stop the kind of urban flooding that occurred when Hurricane Harvey dropped 30 inches of rain on Houston in 2017. The Corps has long favored fighting hurricanes with large coastal engineering projects, but such projects protect only one kind. of flood risks.
Although Ike Dike would be one of the largest hurricane defense systems anywhere in the world, the Corps’ designs indicate that it may not be able to handle a storm surge of Category 4 and 5 hurricanes. The original Ike Dike concept was the brainchild of a Professor at Texas A&M University, who proposed a series of barriers 17 feet high that would surround the entirety of Galveston Bay, sealing it off from the Gulf of Mexico. Another group of experts at Rice University later proposed complementary project It would line the interior of the bay with dikes and artificial islands, providing a second layer of defense for downtown Houston.
The version that Legionnaires eventually settled on is Much less ambitious. Its dune will only rise 14 feet, less than the height of a hurricane storm during Hurricane Ike itself. The final design also leaves a gap on the western side of the bay where the boom could enter unhindered, not requiring a second line of defense like the network of artificial Rice Islands; The agency considered both options but decided they were not worth the money.
The small size of the project means that large boom events can blow through the dunes or even pass through the central gates, pushing towards the city just as Hurricane Ike would have done. The Special Corps analysis found that even with the project, the Gulf still suffered annual storm damage of more than $1 billion on average. As sea levels rise, the barriers will become less effective, increasing the risks even more.
Experts say the agency will likely downsize Ike Dike to comply with Reagan-era regulations designed to limit federal spending. The rule requires the agency to perform a “cost-benefit analysis” for every project it undertakes, ensuring that the project will prevent more dollars in future damage than it costs to build it. But the Corps can only consider “benefits” that occur in the first 50 years after a project is built, and can’t justify paying for full protection against large storms. A gate system might protect against a major flood event for 500 years, for example, but the dune barriers next to it would only provide protection against a much smaller flood event for 50 years.
Jim Blackburn, an environmental attorney who teaches at Rice University, said the agency’s cost-benefit constraints mean Ike Dike will do little to protect Houston itself. Coastal communities like Galveston will become safer, but the existential threat to Houston will remain.
“There will be some benefit to the Ship Channel (and Houston), but it only lasts until a certain storm size,” Blackburn said. “There is a new reality ahead, and the Corps is not capable of responding to this kind of evolving risk.”
In response to inquiries from Grist, an Army Corps of Engineers spokesperson defended Project Ike Dike, saying it would reduce damage from medium-sized hurricanes by up to 77 percent and prevent an average of $2 billion in damage each year, despite “residual risks.” “You will stay.
“The investment (in Ike Dike) pales in comparison to the hundreds of billions of dollars in devastation that coastal Texas communities will suffer from the direct hit of one or more massive hurricanes,” the spokesperson said. “No other proposal meets the stringent requirements of the federal government, can be completed in the proposed time frame, (and) receive congressional approval.”
Even if Ike Dike becomes a reality, Houston is far behind in addressing flood risks that don’t come from Galveston Bay. When storms pass over the Texas coast, the rain they drop drains into the Gulf of Mexico. As it moves towards the ocean, this water It flows straight through Houston Along serpentine watercourses called bayous. These bayous run past Tens of thousands of homesSome of them are within feet of water. The largest of them, Buffalo Bayou, runs through downtown.
Legion itself Responsible for some flood risk On Buffalo Bayou. In the 1930s, the agency attempted to control flooding in the waterway Building two dry tanks They can trap water during heavy storms and keep it out of the city center. But the agency did not clear enough land to store water from A huge storm like HarveyThe developers later built several subdivisions on the land that the Corps had built He knew he would drown. When these subdivisions filled with water during Harvey, the homeowners sued the agency for damages and won a settlement. It could exceed 1 billion.
Even as he progresses with Ike Dike, the Corps is looking for a way to control this urban flood as well, but they don’t have many good options. its initial proposals to Buffalo Bayou Line with concrete and Construction of a third dry tank In the open wilds outside of Houston it collapsed amid concerns about environmental impacts. The agency’s other big idea, which has gotten some support from Houston-area flood officials, is Digging a giant tunnel for rain water between the flood-prone city and the Gulf of Mexico, diverting excess water underground before it submerges metropolitan Houston. But this project, too, faces major challenges: The tunnel system would cost up to $12 billion and take more than a decade to build.
Corps projects also ignore other areas of the city, most of which run through Black and Latino neighborhoods, according to Susan Chadwick, director of Save Buffalo Bayou, a local environmental nonprofit. Instead of trying to control those waterways with “gray infrastructure. “
“We believe in stopping rainwater before it floods streams,” said Chadwick. “We need to focus on slowing down the water and retaining it as it falls, and we need more individual and community efforts to stop, slow, spread and absorb storm water.”
The Corps tends not to fund this kind of green infrastructure, Chadwick said, and disadvantaged neighborhoods often lack the political clout to advocate for major federal infrastructure investments. Houston and surrounding Harris County have raised some funds for local flood control projects, including through a Bond issuance 2018, but without federal dollars, it would be difficult for the city and county to keep up with the risks. (The Army Corps of Engineers did not respond to questions about inland flood projects prior to publication.)
Houston isn’t the only place where the agency has proposed mitigating hurricane risks through ambitious engineering projects. Corps officials erected large structures of seawalls in many other cities prone to hurricanes and storm surges, including Norfolk, Virginia, And Charleston, South Carolina.
In some cases, local residents have rejected the agency’s projects for being too expensive or harmful to the environment. Officials in Miami recently The Legion’s plan was rejected to a wall that would have blocked ocean views, and New York environmental groups torpedoed plans to build a five-mile gate that would It stretched over the 10-mile bay Between Long Island and the Jersey Shore. Legion returned to New York last year with the escort $52 billion plan to build 12 smaller gatesBut the same groups have also rejected that plan, saying it still places too much emphasis on storm surge rather than sea level rise and nearby flooding.
Texas has gone in the opposite direction, embracing the Legion’s focus on gray infrastructure. As Blackburn sees it, these projects will keep Houston out of trouble with the hurricane.
“Houston is an engineering city, and this is a great engineering solution,” he told Grist. “But I think what you’re seeing is an agency operating with concepts from the 1980s facing flood problems in the 21st century.”
This article originally appeared in grist in https://grist.org/extreme-weather/houston-ike-dike-army-corps-flooding/. Grist is an independent, non-profit media organization dedicated to telling stories of climate solutions and just futures. Learn more through grist.org