The ancient practice of irrigation ditches in the Sierra Nevada dates back to the Middle Ages, when Muslims already “sowed” meltwater to recharge the mountain’s open channels and guarantee its supply. Today, a network keeps this practice alive, in whose conservation the Life Adaptamed project has also collaborated for being a model of adaptation to climate change.
Accessing the highest mountain range in southern Europe, the Sierra Nevada, where the eye can see the Mediterranean Sea in the distance, is not an easy task. After twists and turns along the road, we reach a peak where the body of water on the horizon merges with a rugged mountainous landscape.
We arrive here, on the south face of what is now the Sierra Nevada Natural Area (comprised of the National Park and Natural Park of the same name), to see up close the work carried out by the acequieros in the area, together with scientists and collaborators from the Life Adaptamed project .
There, Antonio Ortega García, president of the irrigation community of Bérchules, welcomes us. Each municipal term has a different grouping and this 58-year-old acquiero maintains, along with three other companions, one of the most important ditches in the entire area: the El Espino river basin. Thanks to it, the water that reaches a large part of the Trevélez valley and Bérchules itself is collected.
Irrigation ditches are channels dug in the ground to recharge and channel water from the melting of high mountains. Those responsible for Life Adaptamed, a project that includes 45 actions to protect the ecosystem services of the Sierra Nevada National Park and Natural Park, the Cabo de Gata-Níjar Natural Park and the Doñana National Park and Natural Park, joined hands with the acequieros to recover some of these channels.
A collaborative project with local agents
“Presentations were given in places where they were really needed. It took over twenty years for this channel to recover.”, explains Ortega García. “As much water as possible has to reach its destination because it gets lost on the way. This year they are already working with the water that flows through the pipeline, which supplies cities that are far away“, continues.
Another example is the Trevélez channel, which supplies water to springs in the municipality of Murtas. “This city is many kilometers away. The water is guided from an altitude of 2,700 meters to these places”, explains the acquiero, who for years dedicated himself to construction and who knows the profession by family tradition. He saw his father working in the ditch and his children now see him.
“The particular case of this channel in which we intervened is that it had operating problems, so the amount of water that came out in the last thirty years has nothing to do with what it is now.”, says José Miguel Barea, biologist at the Andalusian Environment and Water Agency — an entity that is also participating in the project—.
From the International Union for the Conservation of Nature, which is another of the seven organizations that integrate this Life project, they highlight: “We work with the people of the territory based on humility, we do not seek to teach anything or impose anything on them. They know very well that by conserving high mountain meadows and traditional irrigation, they will have water in the summer and will continue to live. We all win because they are systems that protect us. It’s a collaborative project “.
The process that follows the drains of care and the water that “seems” in the high mountain is delayed and filters out of the mountains, across the land from the surface, to channel it through the drains and that reach the months of summer. “Like a sponge, the earth works. It is a system that, according to the studies in which we guide the water from the top of the Bérchules, has been doing so for twelve centuries.”, Argues Ortega García.
In fact, this network of irrigation ditches in the Sierra Nevada is considered the oldest aquifer recharge system in Europe, according to a study published in Journal of Hydrology.
From the times of Andalusia to our times
In a world facing different climate crisis scenarios, adapting to them is essential to be able to live in decent conditions. This is something that the inhabitants of the Sierra Nevada did not take into account centuries ago, but in the Middle Ages they unknowingly established a groundwater recharge system that would become the oldest on the continent.
The fact that you have achieved it today is no accident. On the one hand, its management has been maintained from generation to generation in this mountainous semi-arid region and, on the other, it is a clear paradigm for the aquatic future of the area and other alpine ecosystems threatened by desertification and climate change. . “This managed aquifer recharge technique activates several springs located in the middle of the slope and increases the base flow of rivers.”, they point out in the study conducted by the Geological Institute of Mining of Spain on the El Espino channel.
Water from ditches dug in the ground, coming from the melting of the headwaters of mountain streams and rivers, infiltrates the upper part of the valleys. In this way, it flows more slowly on the slopes, and contributes to the active recharge of numerous springs in the middle of the slope, increasing the base flow of the rivers it reaches. “The sowing process takes practically the whole year. The ditches are just to get water, they don’t draw water from the river”, Indicates Ortega García.
The first thing the acequieros do in late summer is to clear the ditch. Later, when it starts to rain or melt, the acquiero climbs every day to guide it to the top, with a tool so that it opens smoothly and doesn’t get cloudy, so it doesn’t obstruct the ground. “From there, it goes out into fountains miles away. Water is almost permanent if you drive”, states.
In this area, there are a total of 600 community members registered with water rights. From small farmers to others with larger lands. An area of around 80 hectares is irrigated where products such as zucchini, tomato, beans or eggplant are cultivated. Ortega García decides exclusively on tomato Cherry.
In its area there are 40 kilometers of linear irrigation ditches, with four different names, three to face, although one is still to be cleared. “I would like to get it back as it is part of my community and it is inactive”, The acequiero is released on request.
Rut Azpizua, responsible for the technical coordination of the Sierra Nevada Global Change Monitoring Program at the Environment and Water Agency, highlights an additional setback: “Not all ditches have a community of irrigators behind them, which would be ideal. Rural depopulation is also a problem. Therefore, what we have been doing over the years that the project lasted (which only included recovery), is to carry out maintenance work to optimize efforts when we see that there was a very interested community of irrigators behind”.
Biodiversity Highways
Altogether, in Sierra Nevada, more than 3,000 km of trenches are inventoried. For the scientists who were involved in its restoration, it’s a nature-based solution. Specifically, Barea considers them as highways to biodiversity. “They contribute to more insects and more pollination.”, He testifies.
Regino Zamora, professor of Ecology at the University of Granada (UGR) and scientific coordinator of this initiative, also highlights the role of the climate crisis in mountain areas like this one and how to deal with it: ”This in an anthropized landscape, that is, there are parts that can be considered more natural, but it is an environment that is historically managed by man. In addition, it has a climate that conditions it.”.
Scientific studies point to high mountains as especially sensitive to these changes, and the enclave where we find ourselves, the Mediterranean basin, is also sensitive. A “double prize” that, thanks to its harsh ecology, with experience in extreme climates – very cold winters and hot summers -, allows you to obtain a passport to the most inhospitable conditions. “It is very heterogeneous, a mosaic that allows it to survive better”Explains Zamora, who believes that it is necessary to maintain ecosystem services in a scenario of climate change.
The UGR scientist asks for this, “maximize and maintain resilience, train them to respond on their own to changes that come to them, and actions at specific points with a scientific basis”. Thus, the intervention is carried out in irrigation ditches or in the diversification of the forest mass on a small scale, and support is given to irrigation communities.
Luis Enrique Santamaria Galdón, researcher at the Doñana Biological Station (CSIC), adds: “The adaptive management strategy is based on two pillars: avoiding solutions that, although they seem to be optimal, can have no return effects; and learning by doing, that is, instead of betting on a single solution, trying to design the management to have different options and learn from them and do better”. This tree species is the most threatened in the region.
Experimenting with small-scale forests
The action that had the most budget for the project in the Sierra Nevada was the treatment of pine forests, which also took place in Doñana and Cabo de Gata-Níjar.
“The four species of pine trees existing in the area were considered, and for each of them a location was researched and actions were designed with different variables. It was a matter of experimenting to discover the services that this mountain provides, as if there are still shadows for a series of species to live under the trees.”, shows Azpizua.
This was complemented by other actions in oaks and holm oaks, with the same philosophy: playing with different intensities and seeing how to manage the residues from branches that remain in the forest. It was about learning from experience, acting from the location and the demonstration, because the more diversity and heterogeneity there is, the greater the possibility for these trees to adapt to changes.
In this environment, the researchers took into account that in the last 60 or 70 years the Sierra Nevada has gone from being a mountain without any more, to a place of tourism and exponential change in uses. People visit the mountain to walk, watch birds or appreciate the trees because they prevent erosion and correct CO.two The services that natural spaces provide us are a benefit for everyone.