Aissa Derhem first heard about fog collection when he was studying for his Ph.D. in Canada in the 1980s. He read a story in 1989 about one of the world’s first projects to collect water from the air, which had just been started in Chile’s Atacama Desert by FogQuest.
(FogQuest is a non-profit Canadian charity, founded in 2000, which has been planning and implementing water projects for rural communities in developing countries since 1987, using fog collectors and effective rainfall collectors to collect natural atmospheric sources of water. Currently, it is working in eight countries.)
But it wasn’t until Derhem was visiting his parents’ mountainous village, Mount Boutmezguida in southwest Morocco, at the edge of the Sahara and about 35 km (22 miles) from the Atlantic Ocean, that he realized it was perfect for a fog collection project that could solve the community’s perennial water shortages.
Before Dar Si Hmad started the fog project in 2015, women would walk five kilometers a day before sunrise to fetch water from open wells during the dry season. Girls would be pulled out of school to help fetch water. But drought, overuse and climate change made water harder and harder to get, as groundwater levels dropped. The rest of the year most households gathered rainwater in cisterns and bought water, which was delivered to their cisterns via water-trucks. Almost half of the village’s residents left rural life for the city, hoping to make a living there.
The Anti-Atlas region, where Dar Si Hmad’s project is located, has a very low yearly average of precipitation – less than 132 mm yearly with a very small number of precipitation days – and is considered a Tropical Subtropical Desert Climate. A drought cycle has been recurring since the 1960s, and ongoing climate changes have caused further deterioration. However, there is lots of fog.
Now the project is the world’s largest functioning fog collection project, with a system of nets stretching about 870 square metres. and it has changed the lives of the villagers, bringing running water to their houses and encouraging young people to return home from the cities.
A great deal of research preceded the start of operations. With advisory support from FogQuest and technical and financial support from Dr. Vicky Marzol of the University of la Laguna, the first Standard Fog Collector was set up on top of Mount Boutmezguida in June 2006, and data was collected daily by the TV operators on the summit. In 2009, a Davis Meteorological Station was added that gave detailed information about the weather patterns, showing that the area’s fog yield was at the top of the world’s mean average.
The project’s infrastructure includes 20 fog collection units, seven reservoirs, and five technical sheds, including the solar-powered fog observatory on the mountaintop – the first of its kind in the world. Extensive piping through difficult, mountainous terrain brings the treated water 7,200 linear meters to the main pipes. Secondary pipes then take water to the villages and then tertiary pipes connect the households. Manholes equipped with water pressure regulators facilitate and measure the water intake of each village and household. Homes pay for the water on a prepaid system.
As it happens, fog harvesting is an ancient technique originally used in the Canary Islands, where people collected the water under large trees with foliage that allowed droplets of fog to condense and fall into holes dug underneath the trees. Nowadays, fog collecting (also known as fog harvesting, fog catching, and fog milking) uses specialized mesh, hung between two poles, to trap the water droplets in fog. Wind pushes fog through the mesh, where droplets are trapped, condense, and fall into a container at the base of the unit.
The original nets used were torn by high winds but a partnership with the German non-profit WaterFoundation allowed Dar Si Hmad to develop a stronger net. The CloudFischer is the first maintenance-free fog collector that can withstand wind speeds of up to 120 kph with flexible troughs following the movement of the net in the wind.
Derhem told Thomson-Reuters that he hopes the success of the scheme can help other areas in West Africa and in North Africa, where fresh water resources are among the world’s lowest. He said water levels in Morocco have dropped to about 500 cubic metres a person a year from about 1,500 cubic metres a person in the 1960s.
The art of catching fog. Thomson Reuters Foundation, You Tube, 2018.
Dar Si Hmad website.
Fog harvesting. Climate Technology Centre and Network.
The fog catchers conjuring water out of Moroccan mist. Thomson Reuters Foundation, May 17, 2018