The tides are rising. The only question that remains is how—and whether—we prepare our cities for it. As you might expect, the cities taking the most decisive action are the ones that have been hit the hardest most recently, like Sandy-battered New York, or partially-submerged Venice.


These are far from the only cities working to transform their defenses before the next big storm or high tide arrives, but they're great examples of how even the largest cities in the world are spending billions on unwieldy, politically unconscionable flood mitigation projects. From a pneumatic gateway to a plan to actually let the waters in, a few examples follow below.

Venice's Underwater Pneumatic Gates


One inlet. Image: Wikimedia .

There's no city with an older or more visible flooding problem than Venice—it even has a name for those notorious high tides: acqua alta. It's a problem that Italy has grappled with for decades, and now, it's getting close to finishing a project that's been in the works for almost 30 years.

The controversial project is called Project MOSE, or MOdulo Sperimentale Elettromeccanico. In theory, it's quite simple: There are three thin islands or peninsulas that separate Venice from the sea. Project MOSE is building 78 vast underwater gates at each gap in this long barrier of landmasses—so that when the next flood arrives, they'll be able to stop it before it enters the lagoon.


Image: Wikimedia .

Each barrier is hollow and sits on a hinge, and when the tide is normal, they're filled with water and lie flat against the sea bed. If something's amiss, the engineers can simply fill these gates with air—causing them to pop into position to keep the tide at bay.


If it sounds unwieldy, it's because it is. The project has plenty of naysayers, especially scientists and conservationists who point out that by closing off the lagoon to the ocean, Venice will be massively altering the natural ecosystem of the area.


The control center. Image: Wikimedia .

London's Floating Village


Though the Netherlands have been building floating structures for centuries, the idea of a floating village is new for London. After a year-long competition process, last month London announced the winning firm that will transform its now-defunct Royal Docks—15 acres of water—into a development that will make the city "more resilient."


The idea is lifted straight from flood-prone Holland: Float it. Float it all. Houses, shops, sidewalks, bars. Everything will be anchored to the sea bed, held in place and designed to shift with the water levels. The project, which will be designed by architects dRMM, is also being advised by a number of Dutch floating structure experts, and is expected to go to the planning board next year.


New York's Big Sponge


A few months ago, we reported that New York City had received more than a half a billion dollars to put several flood mitigation schemes into place—or at least kick them off, considering that these projects are on an infrastructural scale we haven't seen in NYC for decades.


One of the most visible will be the Big U, an topographical feature that will run around ten miles of Lower Manhattan Shoreline. Designed by Bjarke Ingels Group, this is a project that will literally change the landscape of the city—including 16-foot-high soil berms, parkland, marshes, and trails along the perimeter edge of the land. This won't just act as extra public space—it will provide an essential "sponge" to soak up the storm surge, the next time a major flood comes around.


The Netherlands' Controlled Flood

While the Netherlands counts as a whole group of cities fighting rising sea levels, it's important to mention it—because it's by far the most prepared and advanced example of the type.


Image: Ruimte voor de waal .

According to The New York Times, 60 percent of the Netherlands' GDP is produced below sea level. When you start running the numbers on how a major flood would effect it, gigantic programs start to seem much more attainable. Like Room for the River, a $3 billion project that's going to have completely transformed the natural landscape by 2015.


Here's the basic idea: To mitigate the biggest floods you will need to let some water in. It's simply inevitable. Instead of trying to block the water with bigger and bigger barriers, we need to let it in—at least in measured amounts. So the Netherlands is spending nine years on a project called Room for the River, which is exactly what it sounds like. Rather than block the surge, the idea is to create enough infrastructure to let it in without flooding the most important parts.


Image: West8 .

Take the project above, by landscape architects West8. They're actually lowering a dike to allow more water to run into the lowlands behind it—rather that allow the flood to breach the dike suddenly and catastrophically.


By 2015, the country will have enough 16,000 cubic metres—per second—without flooding, thanks to 39 of new infrastructural projects, including creating new basins to catch waters, moving dikes, creating high water channels, and many other strategies. While the rest of the world is trying to build walls high enough to keep out the water, the Netherlands are letting it in. It's a fascinating project.

There are dozens of other notable projects afoot out there, all designed to help coastal areas adapt to changing sea levels. I'd love to hear what you think are the most interesting in the comments below.