A year ago, Superstorm Sandy hammered all three international airports in and around New York City. LaGuardia International got the worst of it when Sandy’s 3.7-meter storm surges overwhelmed the airport’s protective berm wall system with nearly 380 million liters of water from Flushing Bay, flooding the airfield and closing it for three days.

In an acknowledgement that LaGuardia’s outdated defenses against extreme weather will continue to be compromised over time, local and federal officials recently approved $37.5 million for a series of engineering projects designed to protect the airport from future natural disasters. The projects include installing new flood-barrier berms around a building that houses critical runway and taxiway lighting systems, building a concrete flood wall around a substation used to power airfield systems (such as the pump stations), and constructing gravity drains to supplement the airport's existing drainage network. Other improvements will focus on emergency backup generators and the power distribution grid.

Such decidedly low-tech actions would serve most major airports well, even in less than extreme conditions. Thirteen of the largest airports in the U.S.—including LaGuardia—have at least one runway with an elevation within about 3.7 meters of current sea level. This leaves those airports increasingly vulnerable to flooding as oceans rise in the coming decades, according to the U.S. Department of Commerce’s National Climate Assessment and Development Advisory Committee in a draft of its latest climate report, released earlier this year (pdf).

Location, location, location
One of the main problems with airports is their type of location—typically on several square kilometers of low, flat wetlands, often near a body of water. This limits air traffic obstacles, ensuring that airports can support as many flights as safely as possible. But it also means that runways and airport facilities have few natural buffers against flooding, high winds and other forces of nature.

Engineers must design adequate drainage systems not just for floodwater from rainfall but also from overflow from surrounding bodies of water, says Stephen Emery, an engineering consultant and director of the consultancy Kubu Australia Pty, Ltd., based in Perth. Flood and storm hardening studies are “pretty standard, boring and slow engineering tasks,” he adds—and for which it is often difficult to get approval.

Like LaGuardia, many major airports are also right at or close to sea level because that’s where the cheap land was at the time those locations were sited, says Lou McNally, assistant professor of applied meteorology at Embry-Riddle Aeronautical University in Florida. In the 1920s through the 40s, when some of the biggest U.S. airports were first constructed, “the nearby city would tell you to build your airport in a swamp,” he adds.

Ronald Reagan Washington National—originally called National Airport—was built on mudflats on a bend of the Potomac River seven kilometers south of Washington, D.C. Similarly, the city of Newark, N.J., developed Newark Liberty International Airport—once the world’s busiest—on 27.5 hectares of marshland, about 24 kilometers southwest of Midtown Manhattan.

Given their vulnerability to the elements, airports must take weather patterns into account when planning for their future. It’s been typical for airport architectural plans to consider 50-year or even 100-year wind patterns, but recurrence rates of severe weather are increasing, McNally says, adding, “The 50-year storm, the 100-year storm are happening more frequently than that.”

Floating airports
The low-lying areas that were once prime sites for new runways and terminals have become increasingly difficult to find, particularly as cities become more crowded. London Mayor Boris Johnson wants to accommodate his city’s burgeoning air traffic by building a new floating facility in the River Thames Estuary that would likely replace Heathrow, which already operates at 98 percent capacity. The Thames Estuary Research and Development Company (Testrad), which is designing the island airdrome, says its proposed six-runway London Britannia Airport would increase the volume of flights into and out of the city as well as provide residents with a more effective buffer against aircraft noise and pollution. The man-made island would be situated to the east of the city, about seven kilometers north from the Kent coast, near where the Thames meets the North Sea and the English Channel.

Britannia Airport is hardly without precedent. Japan built its Kansai International Airport on an artificial island in the middle of Osaka Bay in the late 1980s and early ‘90s. One of the biggest challenges has come from Kansai sinking at a faster rate than anticipated—the passenger terminal sunk by nearly 12 meters between its opening in 1994 and 2000. Initial estimates had the airport’s island “settling” by no more than 11.5 meters over the first 50 years. Settlement will continue to be an issue, but the company that runs the airport claims to have slowed the process by draining water out of the upper layers of the seabed beneath the airport. To protect the facility from storm surges and flooding, Kansai features a rainwater drainage system, seawalls and a “cutoff wall” to prevent groundwater levels rising after high tides.

Britannia would be built behind a belt of seawalls—also called polders—to control against flooding and further protected by a raised perimeter about two or three meters above sea leavel, says Nicola Clay, director of coastal and marine environment at Royal HaskoningDHV, the international consultancy and engineering company leading the maritime engineering aspects and the environmental impact assessment of the airport. The runways within that perimeter would actually be about one meter above sea level. Engineers would also align the airport’s position with the direction of the tidal currents and round the edges of the island  to minimize interference with the currents, Clay adds. 

Planning for the unthinkable
Ultimately, even the best-laid plans for airports might not suffice. Typhoon Haiyan reduced Tacloban’s Daniel Z. Romualdez Airport to little more than a runway after sweeping through the Philippines earlier this month. Winds blew ashore a wall of water as much as 7.5 meters high. Much of the city itself sits less than five meters above sea level. Damage to the airport created a bottleneck for responders and relief workers trying to fly in and provide aid to residents immediately after the storm. “It’s likely that nothing could have been done to protect Tacloban airport under such extreme circumstances,” Emery says. Still, he adds, the kinds of investments being made at LaGuardia probably should have been made sooner than Sandy’s one-year anniversary.

For most airports, adaptation to new weather patterns has become an integral part of managing air traffic, McNally says. About the only thing to be done at this point, he adds, is to recognize that previously unthinkable weather will become a recurrent and irrefutable reality and plan around that.