Fog Catchers Bring Water to Parched Villages

Helen Fields, National Geographic magazine 9 Jul 09;

When people from rural Peru move to Lima, the capital, they're looking for a better life. But things can be tough.

It's hard to find a job in the city. The jobs they can get—bus driver, street vendor, construction worker—don't pay well.

And the cheapest area to live is high on steep hills on the edge of the city, where landslides are common and water is scarce.

German conservationists and biologists Kai Tiedemann and Anne Lummerich, who run Alimón, a small nonprofit that supports Latin American development, are trying to help with the last of those problems. Since 2006 they've been working with new settlements on the outskirts of Lima to set up special nets that scoop water directly from the air.

Rain rarely falls on these dry hills. The annual precipitation in Lima is about half an inch (1.5 centimeters), and the city gets its water from far-off Andean lakes.

But every winter, from June to November, dense fog sweeps in from the Pacific Ocean.

With a few thousand dollars and some volunteer labor, a village can set up fog-collecting nets that gather hundreds of gallons of water a day—without a single drop of rain falling.

Ancient Technique, Modern Salvation?

As far back as 2,000 years ago, desert villages and other rain-starved communities around the world may have started harvesting fog that collected as water and dripped from trees, said Robert Schemenauer, executive director of FogQuest, a Canadian nonprofit organization that helps communities set up simple collection devices.

Serious work on collecting fog started about a hundred years ago. Since then, fog catchers have been used successfully—though on a small scale—all over the world.

Fog collection will never be practical on a large scale. "You aren't going to put up thousands of fog collectors and try to provide water to Los Angeles," Schemenauer said.

But in small communities that can't get water from wells, rain, or a river, the technique can be a lifesaver, freeing poor people from exorbitant water prices.

That's exactly what's starting to happen in Peru.

Lummerich and Tiedemann, the German conservationists, based their fog collectors on a design Schemenauer developed with Chilean researchers for villages in Chile in the 1980s.

Peru's capital was a natural place to try the technique: "Every summer the [Peruvian] newspapers are full of warnings that Lima will be without water someday," explained Lummerich.

Glaciers are shrinking in the Andes, Lima's source for water, and climate models predict that the trend will continue. An engineer with the Lima water company told Lummerich and Tiedemann he thinks the city could start experiencing serious water shortages within a decade.

In the meantime, Lummerich said, "we just can't waste this water [from fog]. It's a huge waste."

Harvesting Fog in Bellavista

Lummerich and Tiedemann searched for the right place to carry out their project, which received support from the National Geographic Society's Committee for Research and Exploration and the Bayer AG company. (The National Geographic Society owns National Geographic News.)

The researchers found that place on the steep slopes around Lima.

The newcomers who settle there build plywood shacks on unclaimed land. If the residents stay long enough, they can obtain the title to the land from the government.

One of the requirements for getting the title is to plant trees upslope. Earthquakes are common around Lima, and trees help stabilize the land and guard against landslides.

But trees have needs. "It's not really a problem for them to plant a tree," Tiedemann said. "The problem is the irrigation." And that's what he and Lummerich aimed to help with.

The village of Bellavista (population about 200), was founded seven years ago in the hills 10 miles (16 kilometers) south of downtown Lima. Tiedemann and Lummerich were won over by the community leader, Noe Neira Tocto, who made it clear that his village was motivated to do the hard work needed to make the project a success.

Since its founding, Bellavista has attracted people from all over the country.

Most come from farms, so they have the skills to grow their own food, but the fertile soil in Bellavista has gone to waste, since there's not enough water for irrigation.

Villagers have to buy water for everything—cooking, cleaning, drinking—from trucks that drive up the steep hill every week. The residents pay ten times as much as people farther downhill, who are connected to the municipal supply. For a family of four, water can come to the equivalent of U.S. $7 to $10 a week—a huge sum in a village where family income might average about $40 a week.

When the Bellavista fog-catching project began in 2006, people from the village did all the heavy lifting and digging. They had to lug 94-pound (43-kilogram) bags of sand about 800 feet (250 meters) up the steep hill—about 15 minutes a trip—to stabilize the nets and build pools to gather water collected by the fog catchers.

Even as they worked, though, the villagers thought the fog-catching idea sounded a little crazy. "They listened to us politely, but they didn't really believe that it worked," Lummerich said.

When water started appearing, it seemed too good to be true. "At the beginning," Lummerich said, "the people from the village thought Kai carried the water uphill during the night to fill the tanks, because they couldn't believe there was so much water."

"Like Opening a Tap"

Fog collection works not by condensation, which is what happens when water vapor hits a cold surface and transforms into a liquid. In fact, the water in fog is already in liquid form—it's just in very, very small drops.

The collectors Lummerich and Tiedemann started with look like giant volleyball nets, 13 feet (4 meters) tall and 26 feet (8 meters) wide. The nets, perpendicular to the prevailing wind, stretch between pairs of wooden poles. The top of each net is 18 feet (5.5 meters) above the ground.

As wind blows the heavy fog through, tiny droplets stick to the coarse woven mesh, made of a kind of plastic netting that is designed to shade young fruit trees. The netting is easy to find—any hardware store in Peru carries it—and relatively inexpensive.

As more and more tiny droplets stick to the net, they clump together and form drops, and eventually gravity pulls the drops down into a gutter. From there, the water flows through tubes into two brick tanks and a pool—all built by villagers—which together hold more than 25,000 gallons (94,635 liters) of water.

On a good day, a single net in Bellavista can collect an impressive amount of water—more than 150 gallons (568 liters).

"It's amazing when you're up there and it's foggy and the wind comes in. Then you hear all the water start running into the reservoir," Lummerich said. "It's like opening a tap."

She and Tiedemann also designed another fog collector, with multiple layers of netting to better catch a shifting wind, which they erected in 2007. The new design has collected more than 600 gallons (2,271 liters) in a day without taking up any more space than the original nets.

Bringing the Natural Water Cycle Back

Two other villages near Bellavista now have the fog collectors as well, and Lummerich and Tiedemann hope to bring more someday to other dry communities in Peru.

In the meantime, the people of Bellavista are using water from their seven fog catchers to plant trees higher up on the hill, in hopes of eventually getting the title to the land they live on.

They are growing tara trees, which bear a valuable fruit whose tannins are used for treating furniture leather. The money they'll earn from selling the fruit will help pay for maintaining the fog-catching installations.

Eventually the trees should be able to collect their own water, as the leaves act like fog collectors themselves, accumulating the water, which should drip down and replenish groundwater.

Even after the trees are taken care of, there's enough excess water now to feed gardens below the fog collectors.

Tiedemann's dream is to bring the natural water cycle back to the hills around Lima.

Some of the city's oldest residents remember when the hills were covered in trees. Those trees would have taken their moisture from the air, too, and the excess would have added to groundwater.

Tiedemann thinks it could happen again. For him and Bellavista's villagers, the 700 young tara trees now growing on the hillside mark the start of a dream coming true.