“Acequias” is a system of water management known as “sowing water”. The word is derived from the Arabic word “as-saquiva”, which means “water conduit” or “water bearer”, and “acequias” in Spain’s Sierra Nevada are a very positive remnant of Moorish rule there between the 8th and 10th centuries.
Each year, when the warmth of spring returns to the Sierra Nevada and the thaw begins, snowmelt is diverted from the headwaters of rivers into earthen, porous channels dug into the mountainside. As water flows through the gently descending “acequias”, ranging in length from tens of metres to kilometres, it’s diverted to areas along the upper valley known as “simas”, where the channel empties and seeps into the ground, “sowing water“. As water percolates through the subsoil, it replenishes aquifers and feeds springs and streams that emerge further down the mountain. The “acequias” of the Sierra Nevada are the oldest underground aquifer recharging system on the European continent. They date back more than 1,200 years.
Where water is “sown”, high in the valley, determines where it eventually surfaces downslope, and where it can be “harvested” to irrigate orchards, crops and gardens throughout the thirsty summer months. Without this system, most snowmelt and rain would flow quickly off the steep slopes, as runoff in rivers. Sowing water through acequias slows the flow of water from the mountains, extending its availability for when it’s most needed during the dry season.
Research has demonstrated that sowing water, using “acequias”, doubles the recharge of water in aquifers. The system follows the principles of eco-hydrology, which uses the regulating effect of vegetation, soil and aquifers, imitating nature to regulate water, instead of building concrete structures (dams) that alter the flow of water upstream and downstream.
The “acequias” system in the Sierra Nevada is part of a 3,000km (1,800 mile) irrigation network built by the Moors. This water management technique, introduced from the east, transformed the landscape and agriculture in what was then Al-Andalus. “Acequias” made life possible for agrarian communities, conserving and distributing scant and seasonal water resources throughout the rugged mountains. In the newly fertile conditions, the abundance of crops introduced by the Moors thrived, among them almonds, artichokes, chickpeas, aubergine (eggplant), lemons, pomegranates, spinach, quince, walnuts and watermelon.
Without these ancestral water channels, life as it now exists here now would not be possible. No one knows this better than those who depend on the water, which is why the “acequias” in, for example, Mecina-Bombarón has been kept in continuous use for over a thousand years, having weathered many social, cultural, political and environmental changes. “The “acequias” is the life of the village. Without the “acequias”, all these villages would be a dryland, and all these farms would be dry. It was very well planned,” says Matilde Ruiz, who has lived her entire life in the village, standing in front of her garden planted with aubergine, lettuce, garlic and onions.
However, the Moorish Water conservation system is not the only example of such human ingenuity. An indigenous water management system developed independently in Peru around 1,400 years ago uses similar principles. The Peruvian government is now, belatedly, investing in this proven system rather than building more dams.
When water sowing systems flow they provide numerous ecological benefits, too. Where such systems are used in Ecuador, biodiversity is higher than in areas where they haven’t been implemented. In New Mexico, the “acequias” channels function as ecological corridors, enhancing plant cover and diversity, which reduces soil erosion and supports wildlife habitat.
Many experts think that conflicts over the control of water resources could well trigger the next world war: Localized water wars are already in progress in the western states of the U.S. Thousands of UNESCO-funded wells throughout India are highly contaminated with arsenic. The catastrophic droughts in Africa, and the disappearance of the Aral Sea are only some examples of how we have screwed-up our most precious resource. It is gratifying to see that some people, somewhere, have realized that massive amounts of concrete is not the answer. Local skills, and historical knowledge, can do a better job in many instances.
We obviously need to address human contributions to climate change as well but some of the answers are sitting right in front of us. “Acequias”, Moorish water management, is one of them.