The Atacama desert in North Chili is in the rain shadow of the Andes Mountains. Although it borders the Pacific Ocean, a persistent cold current that is known as the Humboldt current The moisture levels in the air relatively low. Clouds form, but disappear quickly. As a result, rain rarely and in small quantities – a few millimeters per year, on average in some parts. In other parts, decades old weather stations have never registered a rainfall. Outside of a handful of valleys in Antarctica, the Atacama is the driest place on earth. The inhospitable landscape of sand, bare rock and salt apartments is so extreme and alien that it is used by researchers as a proxy for Mars.
Yet people live there – usually in a little coastal towns and villages. Iquique, the regional capital of OceanSide, is home of more than 230,000 people. Only interior and Upslope from Iquique is the fast -growing municipality of Alto Hospicio, which is broken More than 140,000 people (higher than 100,000 in 2012) in the midst of a lithium mine construction.
Fresh water comes from an underground aquifer, which has not been meaningfully renewed by rainfall for almost 10,000 years. As more people trust the aquifers, it dries up. In the end there will be nothing left. Desalination installations, which remove salt from ocean water, can fill part of the needs, but they are expensive and energy-intensive to run, especially for a low income such as Alto Hospicio. Most desalination installations in the regional service mining activities, not people.
An alternative, even-on-drip and cheap water source can help to resolve the fast-growing water crisis. And it is water that has hidden itself in sight. Harvesting fog is a durable, simple method for collecting moisture from low -lying clouds. It has been used for a long time in the countryside All over the world to support isolated villages of several hundred people. But a new study suggests that it could work on a much larger scale.
An analysis Published on February 20 in the diary Frontiers in Environmental Science suggests that fog harvest could meet the needs of the informal settlements of Alto Hospicio, which offers no less than 300,000 liters a week to 10,300 people, which are usually disconnected from the formal water distribution system. They currently rely on the disappearing Aquifer, but that water is supplied to them through trucks instead of pipes, increasing costs and reducing reliability and accessibility. For residents of these settlements, the water supply is even more severe than for the rest of the inhabitants of the city, so FOG offers an even greater chance. In addition to drinking water, fog harvesting can also be used to irrigate green spaces in the region, or to nourish hydrocropic agriculture that offer people a cheap source of local, fresh food.
In itself: “This water is not going to save the city,” says Virginia CarterCapital study author, a geographer and a university teacher at the mayor of Universidad in Chile. But missing is a source that can make a real difference, she says. “It could contribute, and in many places it can be important,” Carter explains, especially since Alto Hospicio continues to grow and climate change makes the existing water supply still weak.
Harvesting fog depends on a low-tech setup. Usually a fine plastic mesh, such as the type that can be used to shade heat -sensitive garden beds, is strung a few feet in the air over two support piles. A gutter under the mesh channels the moisture that condenses on the panel in a storage container, so that it can be easily collected. The more panels and the larger surface of the use of mesh, the more water is harvested.
Unlike the Aquifer under the Atacama, Fogwater is a potentially renewable resource. Low clouds are routinely brought from the Pacific and blow overland. Without the mesh, the moisture in the dry air evaporates as the temperature rises every day, but with that the fog would only be temporarily confused – which offers valuable fresh water for people before it is treated and cycles back in the ocean.
To show that the harvesting of the fog would be worthwhile for Alto Hospicio and Northern Chili, Carter and its co-authors combined a year of observation measurements with satellite images and mathematical modeling of the fog cycles of the region. The researchers have set up two “standard mist collectors” of one square meter at different heights, together with a weather station to monitor humor moisture, temperature, wind speed and other variables. They also used remote tele tertection to map the fine -grained height and fog density in the province. Finally, they synthesized this and other data from existing fog collector projects in a mathematical model intended to estimate how much fog could be harvested at different times.
They discovered that the fog is very seasonal and appears from May to October (the winter of the southern hemisphere in the spring). It peaks in June at night and early morning, and disappears anything but in the warmer months and in the afternoon. In the zones directly around Alto Hospicio, according to the study, fog collectors would produce an estimated average of 2.5 liters of water per square meter mesh during the fog season.
At this pace, the 17,000 square meters of collectors (slightly more than three football fields) would take to deliver 300,000 liters a week – the same volume of water that is currently supplied via truck to the informal settlements of Alto Hospicio. Carter, however, notes that this is a conservative estimate, since certain areas north of the city have much more fog potential than the average, which produces more than 5 liters per meter mesh per day. If fog collectors were placed strategically, only 200-300 fog collectors (each with about 20 square meters) can reliably offer hundreds of thousands of liters for at least half a year, she explains. Additional storage tanks or ponds can stretch the fog water throughout the year in a source of the entire year. “This is a kind of dream. To develop something like that for Alto Hospicio, “says Carter.
If delivering drinking water to more than 10,000 people is too big a goal, smaller pilot projects can offer a proof of concept. Carter and her colleagues suggest that fog harvest can also be used to irrigate public parks or to offer water to hydropulture farms, with fewer initial investments. Only 110 square meters of mesh would be needed to fulfill the green space needs of the city. A square meter fog collection can yield more than 15 kg of leafy vegetables every year.
However, before the dream becomes a reality, further work is needed. The scientists want to verify their model estimates with more measurements on the ground to have the best locations for fog collectors at home. Carter says that she also hopes to test the quality of the harvested water and determine what type of treatment would be needed to make it safe for human consumption. Fog can wear exhaust particles, bacteria and microplastics – like any other natural water source. Still, even untreated, the water could still have applications in agriculture or mining.
And the research is already ahead. Carter and her colleagues are planning to release a publicly accessible, detailed fog card for the whole of Noord -Chili later this year based on their model. She hopes that local and national government officials will notice it. “This study is a very clear example of how scientific knowledge [can] Contribute to public decision -making and policy, “she says. “We have a problem: we have no water and it gets worse. But on the other hand there is a solution. There is this water and wait. We just need a logical way to harvest it. ‘
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