Camanchaca, collecting the water of the clouds

Danilo Anton

The coast of northern Chile and Peru is an area subject to the influence of cold sea currents that flow from the south along the coast and to masses of fresh air from the subpolar regions to the tropics. The atmospheric temperature is intensely affected by the rise of deep and cold ocean water.

This combination of factors produces a general cooling of the surface of the ocean and of the air in contact with the sea diminishing the evaporation. The contact between the upper limit of this atmospheric layer of fresh air and the upper layer of warmer air produces condensation of the humidity of the air. This takes the form of a more or less permanent level of low and low thick clouds (Stratocumulus) that give rise to one of the typical characteristics of subtropical coastal deserts. The cloud cover is extensive and frequent but the rains are scarce generating the paradoxical situation of permanent cloudiness without rain, and drought in a humid environment.

Despite this seemingly inhospitable climate, the region still retains a population of certain dimensions. The same phenomenon that prevents rain, makes it one of the most important fishing basins in the world. Although biological resources are often overexploited, they support human communities that live on the Pacific coast.

The interior of the Chilean coastal desert has considerable mineral resources. There are deposits of sodium and potassium nitrates (saltpeter), of copper, tin and lithium minerals, as well as others of potential value whose exploitation is partial and inefficient due to lack of water.

These riches could be used more effectively if the water resources necessary for the operation of quarries, mines and processing plants were available.

However, the lack of water is more apparent than real. The almost permanent cloud cover contains a substantial amount of water that, when used, becomes a negligible source of drinking water for the population.

Camanchaca is the indigenous name derived from the Aymara language used in the South American Pacific coast to name the coastal mists that occur when the Stratocumulus collide with the slopes of the mountain range.

The Camanchaca Project arrived at the International Development Research Center in Ottawa, Canada, where I served as the Program Officer in charge of preparing research projects in Earth Sciences.

It was a proposal of relatively small size that sought to investigate the potential of the camanchaca for the production of water using “water trappers” (types of fog collectors), constructed with plastic mesh curtains (plastillera) lying between wooden posts in order to retain water from the fog. The site selected for the Project was located in the Province of Coquimbo, north of La Serena, on the side of a mountain near Caleta Chungungo, and sought to confirm the results of other investigations that had already been carried out in other areas of the coastal desert in Chile and Peru.

 After studying the background and objectives and methods presented by the proponents I thought that it could be a good opportunity to take a new step towards the application of technology that, in general, was already known. That is, instead of continuing to do experiments, you could find a way to move towards the realization of the ultimate goal that was intended to be to supply a human community with water from the clouds.

The conversations took place with those responsible for the Project in Canada and Chile, and finally we agreed to extend the duration and budget, significantly increasing the number and dimensions of the “trappers” to be able to generate enough water to supply water to the 500 inhabitants of Caleta Chungungo.

The fifty “fog trappers” that were finally installed at an altitude of 800 meters above sea level about 5 kilometers from the coast, were built with 12 meter long plaster curtains lying between five meter high posts. Water droplets suspended in the air hit the plastic meshes and were picked up by gutters located under the curtains. The water from the gutters was received by PBC pipes and taken to open Australian-type tanks where it was stored for later use.

Due to budgetary limitations it was not possible to include in the Project the aqueducts that would lead the water from the fog trappers to the town, but still, we prefer to continue with the Project and later we would try to solve this problem.

The Project was successfully executed. The fog trappers generated enough water for the objectives pursued and in a short time the tanks were full and pouring waters that flowed down the slope without any use.

Finally, support was obtained from the Canadian Embassy in Chile, from the C.I.I.D. and government that allowed to install a system of aqueducts, treatment and distribution with which it was possible to supply drinking water to the homes of the town.

When the system was inaugurated, local people hung up a parade that said "Thank you Canada for this miracle."