Here Come the Floods As Water Levels Rise, Designers Find Sometimes Counterintuitive Solutions

A warmer world means higher seas. Global warming not only accelerates glacial melt, but also causes ocean water to expand in volume. Projections vary widely, but seas will likely rise by at least seven inches by 2100—and possibly by as much as several meters, according to NASA climate scientist James Hansen. It doesn’t take a climatologist to realize one of the immediate, pressing consequences of these figures: flooding. And since many of the world’s largest cities sit on low-lying coasts, these rising oceans could lead to many more Hurricane Katrina-level disasters.

Flooding, of course, has long been a fact of life for many coastal towns, and some old technologies still have merit. Levees, dikes, seawalls, the guiding hand of the U.S. Army Corps of Engineers and countless regional agencies will continue to offer flood protection. But the coming rise in sea levels also calls for new measures. “The whole water management system of our country needs an overhaul,” says George Sorvalis of the Corps Reform Network—and that includes the development and implementation of new technologies.

One idea is to build broad dikes rather than tall ones. Particularly in an area where massive developments are below sea level, the use of broad dikes—which might overtop, but never breach—could prove essential. Other small modifications could dramatically improve the utility of levees. Some engineers are proposing “smart levees,” equipped with monitoring systems that would help officials better understand how to improve and maintain levees, and when to evacuate areas usually protected by them.

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From top to bottom: High tide, low tide and no tide at the innovative Dutch “waterplaza,” a city square designed to flood. © VHP stedebouwkundigen + architekten + landschapsarchitekten

And there are more ambitious design ideas, too. Ivor Van Heerden of Louisiana State University has urged massive restoration of the barrier islands in the Gulf Coast; along with the coastal wetlands (sometimes called “nature’s levees”), he considers these the first, best defense against floods. Sufficient funds have been hard to come by, but Van Heerden is optimistic: “We firmly believe [that with] Obama in office, we”ll start to see the federal government putting a lot more attention on this area. Conceivably, within two years, we could be rebuilding the barrier islands,” he says.

Many of the new designs for rising sea levels grapple with the side effects of other designs. Seawalls are dependable against storm surges, but they severely disrupt coastal ecosystems (which the world’s seafood industry depends on). Kristina Hill, associate professor and director of the Program in Landscape Architecture at the University of Virginia, has designed floating sea grass beds to use in combination with dikes as a possible solution. She calls them “living sea walls,” which she describes as “a kind of a “skirt” of living systems that we can bring inland with us as our shoreline recedes.”

While these designs hold real possibility, implementation has been slow to follow. “At this point we’re at what Disney calls the “imagineering” level,” says Will Travis, executive director of the San Francisco Bay Conservation and Development Commission. The commission intends to hold a design competition this year. “Our hope is we”ll get architects, engineers, students, innovators and others coming up with ideas,” says Travis. “The commission will then publicize and award stipends to the best ideas, which will be applied to a specific site along the bay.” The design process will probably be evolutionary, suggests Travis, who points to the analogy of designing for earthquakes. “No one dreamed that the solution would be to design buildings that can move, but that’s what we’re doing now. It’s almost counterintuitive, the way seismic design has evolved.”

One constant source of flood-battling ideas is the Netherlands, where 60% of the country sits below sea level. One ascendant Dutch strategy is, like seismic design, counterintuitive. They adopted a program called “Living with Water,” deciding to allow certain amounts of water into their cities when sea levels rise. Leading solutions include green roofs covered in water-absorbing vegetation (reducing the impact of heavy rainfall) and a novel idea called the “waterplaza,” a city square specifically designed to flood and become, essentially, a temporary pond, helping to relieve stress on the city’s drainage system. The Dutch have even experimented with floating architecture, using a material called aerated concrete.

Dutch scientists Pavel Kabat and Pier Vellinga, in a 2005 article in Nature called “Climate-Proofing the Netherlands,” envisioned a possible “hydro-metropole,” which they say could be a “world in which we have learned how to live with—and make a living from—water.” That last idea—that enterprising minds might find a way to make the coming floods profitable rather than disastrous—is perhaps the most counterintuitive, and intriguing, of all.