The Ethereal Art of Fog-Catching

By Miguel Trancozo Trevino

23rd February 2020

In chronically dry regions around the world, communities are finding ways to live from the water suspended in the air - creating valuable drinking water from mist.

When Abel Cruz was just a boy, near the Peruvian region of Cusco, he had to walk for more than an hour every day to collect water from the nearest source and take it back home. Then he realised that, during the rainy season, drops accumulated in the banana leaves.

"When we saw that, my father and I built natural canals with the leaves to collect the water," he says. "The first drops were a bit dirty and dusty, yet it was useful to wash dishes."

The leaves, however, only lasted for around two weeks. "So we cut bamboo in half and we replaced the canal pipes with them, which lasted a lot longer," explains Cruz. "That is how I got involved with collecting water."

Today Cruz is collecting water in a very different way – he catches fog.

With large sheets of mesh strung up on hillsides, it is possible to harvest the thick mists that drift across the arid Peruvian landscape. Tiny droplets condense on the netting and dribble down into pipes that carry the water into containers where it can be used to irrigate crops or even as drinking water.

Each net can capture between 200-400 litres of fresh water every day, providing a new source of water for communities that have had no easy access to regular supplies. Cruz has helped to install more than 2,000 of these fog catching nets in eight rural communities across Peru as well as in Bolivia, Colombia and Mexico. The impact has been dramatic.

There are families that are cultivating figs, grapevines and olives, in places where you could never have imagined seeing crops – Abel Cruz

"In places where there was a lot of draughts, nowadays there is agriculture," says Cruz, who has founded an organisation to help supply water to desert communities in South America called Movimiento Peruanos Sin Agua (Movement of Peruvians without Water). "In Tacna, just one man is raising 1,000 chickens with fog catchers. His life has changed radically. It is extraordinary. There are families that are cultivating figs, grapevines and olives, in places where you could never have imagined seeing crops."

Built in a desert on the Pacific coast of Peru, Lima is one of the driest capital cities in the world. The megacity, which is home to more than 10 million people, gets less than an inch of rain each year. Residents are reliant upon highly variable river supplies that are largely fed by water melting off glaciers high in the Andes mountains and ground water buried beneath the city.

For those living on the outskirts of the city, water needs to be brought in by trucks. For those living in poorer, peripheral communities, this is an expensive supply they cannot readily afford, and so they tend to buy the minimum amount of water they need – about 40 litres per day for each person.

But Lima's unique climate means that for much of the year it is blanketed in a dense fog due to the hot coastal air mixing with cool, moist winds from the Pacific Ocean. Known as La Garúa, the thick mists, which occur along the Peruvian and Chilean coastlines, are most prevalent between April and September.

The problem was how to get hold of this airborne water in meaningful amounts so that it could be used. Cruz and residents from communities around Lima teamed up with scientists who had been testing fog nets in other parts of the world and began erecting them on hillsides around Lima, providing residents with a ready supply of water they could collect drip by drip.

The city of Lima is one of the most polluted on the planet, so the water that we obtain in the outskirts of Lima is used for crops and animals but not for human consumption – Abel Cruz

In rural areas this water is often clean enough to drink, but the city of Lima introduces an additional complication.

"The city of Lima is one of the most polluted on the planet, so the water that we obtain in the outskirts of Lima is used for crops and animals but not for human consumption," says Cruz. "In the provinces of Cusco, Tacna, Arequipa, the water is for human consumption."

This is because the water can pick up pollution as it moves through the air over busy cities. Water purification techniques, however, could render this water fit for drinking.

There are now hopes that fog catching could be a way of providing reliable supplies of water to parched communities and settlements all over the world where the right mix of geography and climate can be found. But while new technologies are being brought to bear on the problem, the basic techniques of fog catching go back centuries.

"In one of the first villages on the island of El Hierro, in the Spanish Canary Islands, there are graphic testimonies from the 16th and 17th centuries where you can see how they used the water from the bushes to drink, says María Victoria Marzol, a professor of physical geography at the University of La Laguna, Tenerife. "This island is further south of the archipelago and has always had water problems."

In the 1500s, local people discovered that putting containers under the dripping trees could get them enough water, and they lived on it. "We are talking about 16th Century engravings that already describe this," says Marzol.

In 2009, German conservationists Kai Tiedemann and Anne Lummerich planted 800 she-oak trees in Peru to create a natural fog-catching system that aimed to replicate this ancient technique. During their research they found that trees with vertical, needle-like leaves work as an organic net to which drops of water adhere. They later went on to develop artificial nets that could also capture water.

Marzol has been studying "the hidden precipitation" in fog for nearly 25 years now, partly because modern meteorological instruments struggle to measure its relationship with precipitation. During the course of her research she has witnessed the social transformation that can occur in communities that collect fog water.

Every day, women spent up to 3.5 hours to fetch water from the closer well – Jamila Bargach

In the mountains of Morocco, for example, lack of rain and infrastructure for water supply have historically affected rural Amazigh communities. It created a daily burden for the women there, who were responsible for carrying water from communal wells to their houses.

"Every day, women spent up to 3.5 hours to fetch water from the closer well," says Jamila Bargach, executive director and co-founder of Dar Si Hmad, an organisation that works to create opportunities for vulnerable communities in South-western Morocco, and fellow of the Oak Institute for Human Rights at Colby College in Waterville, Maine. "Elder women, the mothers, the care-takers of the community, would go thirsty because they gave water to the children, the elders and their animals. It was impossible for them to conceive of their animals being thirsty. "Now, the low clouds that cover their towns with mist is changing that."

When Dar Si Hmad started to work with Amazigh women and men in 2006, the fog was seen as a negative element of nature that caused humidity, illness and excessive moisture. Today it is a lifeline. "Some of the wells were simply dry and some of them you have to wait a long time for the water to rise because of the high demand and because there is much less rainfall than 25 years ago," says Bargach.

Getting water from the well is not a forgiving and not a romantic thing. It is time consuming, it is difficult, it can be dangerous but, at the same time, it has its advantages – Jamila Bargach

Now that women have recovered their time, says Bargach, they can use it however they want. While some of them dedicate more time to work on the olive fields, the Dar Si Hmad co-founder says that the fog-catching nets have empowered female members of the community by providing water not only to their households but to the local school and for farming uses too.

Initially, however, the women in the Amazigh towns were reluctant to use the nets.

"Getting water from the well is not a forgiving and not a romantic thing," says Bargach. "It is time consuming, it is difficult, it can be dangerous but, at the same time, it has its advantages. Women can get together. They can talk. It is a way of teaching the younger generation about ways of living."

As the guardians of the wells and suppliers of the water, it also gave the women in the community a certain degree of status and autonomy, but at the same time, with the situation of global warming and climate change, the amount of water available for the community has critically fallen.

"They were the guardians of this source that gives life to the community and to themselves, so once you put the water in the community, you are taking away some sort of control," says Bargach. They key was to work with the women to ensure they could keep this crucial role.

While local men built and installed the fog catching nets, it was left to the women to decide how to collect it, distribute it and use it. They are in charge of tending the nets each day and ensuring the system is maintained.

Similar fog harvesting successes have also benefited communities in Namibia, Bolivia and Chile.

But while fog catching is helping to change the fortunes of remote, rural communities, it could also help to ease the pressure on water resources in large cities around the world. On the coastlines of the US, New Zealand and Namibia there are a number of cities that are regularly smothered in fogs that could be tapped for water.

Some scientists have already proposed demisting fogs over San Francisco as a way of relieving some of the droughts the city regularly suffers.

Unfortunately fog nets require a lot of space and already crowded cities are unlikely to be good locations for enormous fences dedicated to condensing water.

"This technology is absolutely sustainable, efficient and affordable that solves the problem of water scarce in very specific rural areas, where they have gone from an average of four litres of water consumption a day to up to 12 litres," says Marzol. "Yet, we cannot say that it will be enough for water scarce environments that have over 140 litres consumed per person daily."

But some researchers are looking at other ways to tap into the water contained within fog. Chilean architects Alberto Fernandez and Susana Ortega have designed angular kite-like structures as well as huge, spiral-shaped fog harvesting towers that aim to create a large surface area to collect water from as high as possible in the fog. Another project in Chile, called Proyecto Niebla, uses 3D structures to enable the collection of fog regardless of the wind direction.

There may, however, be another problem facing the fog catchers. Out in the Atacama Desert of Chile and Peru, María Victoria Marzol has been conducting research on how climate change is affecting the fogs there. She has been studying a plant called tillandsia, which is able to survive in the arid landscape by collecting droplets of water from the nightly mists.

With climate change, water droplets in clouds are predicted to get smaller, which could mean that mists themselves will get lighter. Marzol and her colleagues have also uncovered clues that suggest tillandsia is moving higher up the desert hills of the Atacama. If this is proven to be the case, it could mean that fog is travelling at a different height, which would put at risk fog-catching in the communities where is currently being harvested.

Her warnings are reminders that even as new technologies offer opportunities to tap into the ethereal power of fog, it may yet slip beyond our reach.

Source:https://www.bbc.com/future