They say in Peru that the one who harvests water without having planted it is a thief. The phrase is full of meaning. In Spain we have a couple of million wells that harvest underground water without their owners knowing that the water is also planted. The Quechua and Aymara peoples have been doing it in the Andes for more than a thousand years by building and managing amunas, lakes and bofedales, among other systems. Water is also planted in Sierra Nevada, Spain, since the time of Al-Andalus, through irrigation ditches.
A green and efficient method against drought
The investigations that we carry out at the CSIC’s Geological and Mining Institute of Spain show that they are really efficient and valid systems to face drought and face the challenges posed by the new climate scenario.
The planting and harvesting system is simple. It consists of diverting and infiltrating water into the subsoil and recovering it in other places a few months or years later. It is not about imploring the gods for rain or building concrete mega-structures, it is about knowing the natural systems of the Earth and taking advantage of them without damaging them so that the water does not stop gushing.
The “Careos”, Sowing and Harvesting of Water in Sierra Nevada, Spain. IGME-CSIC.
One more day without rain
Rainfall ceased to occur in the Sierra Nevada around the month of March. The snowfields on its summits disappeared months ago and some of its emblematic lagoons have dried up. But its rivers, its springs and the fountains of its towns continue to flow with abundant flow.
Why does this singularity occur in Sierra Nevada? The answer is simple: the inhabitants of the southernmost semi-arid mountain in Europe learned to sow and harvest water a long time ago, more or less a thousand years ago, when climatic conditions were very similar to today’s.
What does it mean to sow and reap water?
Planting and harvesting water is a concept coined in the Peruvian Andes, where it has been carried out since before the arrival of the Spanish. With ancestral procedures, rainwater and surface runoff water is collected to infiltrate it (that is, sow it) into the aquifers. Some time later, the water is recovered, harvested, through springs or in rivers, and through the construction of wells and galleries.
In Sierra Nevada, water has been planted and harvested since the time of al-Andalus, through infrastructures known as irrigation ditches.
The careo ditches are unlined channels dug into the ground, some of which are more than 10 km long. These canals are designed to carry the water from the snowmelt from the headwaters of the mountain rivers and infiltrate it where it is needed, reaching the aquifers that develop in the upper parts of the slopes.
After a few months the harvest arrives.
The water infiltrates the ditches along its route and in certain specific areas known locally as simas, calaeros or matas. The time lag, which is normally a few months, from planting to harvest, is due to the slow circulation rate of groundwater through the subsoil. This delay in their output means that the springs and rivers have a practically constant flow throughout the year, without ever drying up.
The system allows modulating the flow of rivers as if they were reservoirs. Without the need for concrete, without external energy inputs (they work with the force of gravity), without the need to import rare earths or strategic minerals from another part of the world. Simple, green and efficient.
The harvest allows supplying the mountain populations and livestock with excellent quality drinking water; it allows the irrigation of crops and pastures during dry periods and contributes to the maintenance of innumerable associated ecosystems and to the increase of biodiversity.
A good part of the oak and chestnut groves of the Sierra Nevada depend on the careos. But, in addition, its collective maintenance, carried out by the irrigation communities, contributes to increasing social cohesion and generating cultural landscapes that are one of the hallmarks of this Biosphere Reserve.
Without these ancestral water channels, all these towns would be a dry land, life there would not be possible.
It is possible to infiltrate twice as much water as in other mountains
Research led by the Spanish Geological and Mining Institute of the Higher Council for Scientific Research (IGME-CSIC) has demonstrated the efficiency, age and resilience of this ancestral aquifer recharge system. We have verified that the water that infiltrates the Sierra Nevada aquifers doubles that infiltrated in other similar mountains.
The system has a high potential to contribute to the achievement of a good part of the Sustainable Development Goals of the EU. This is how UNESCO has understood it, which has recognized the Sierra Nevada irrigation ditches as the first demonstrative site in Spain and one of the thirty worldwide where ecohydrological water management is carried out.
Techniques that can be multiplied
In Spain we have very similar systems in danger of extinction, in which these techniques could be replicated. This is the case of the Sierra de Gredos fishing grounds, the Sierra de Guadarrama hunting grounds or the zayas of the La Valduerna region, in León.
In the Andes, where the range of water planting systems is spectacular (amunas, lakes, tapes, and bofedales, among others), public administrations and national governments support their recovery and replication.
Investigation of these systems, which have managed to reach our days despite significant climatic and social changes, should be useful for planners to consider other ways of managing water that do not confront nature, but work hand in hand. . (YO)
Source: Eluniverso
Paul is a talented author and journalist with a passion for entertainment and general news. He currently works as a writer at the 247 News Agency, where he has established herself as a respected voice in the industry.
