31 Jul 2018 Story Ecosystems and Biodiversity

Benefits of ancient irrigation channels still trickle down Spain’s Sierra Nevada

Sierra Nevada National Park is a mountainous protected area in Andalusia, southern Spain. The mountains are surrounded by pastures, forests, and crops that provide services to more than 90,000 people in the protected area.

Water management in the park, which covers more than 2,000 square kilometres and ranges from 860 to 3,482 metres in altitude, is key to sustaining economic activity as well as ecosystem functioning.

From the ninth century AD onwards, Muslim settlers built more than 3,000 km of irrigation channels on the mountain slopes. Many of these channels are still in use today, diverting water from the springs and streams at higher altitudes and delivering it to the lower-lying crops, grasslands, and forests. This process slows down the hydrological cycle, making good use of the water resources.

As part of its ground-breaking ECOPOTENTIAL project, the European Union has been using satellite images to assess how this network of channels is affecting the functioning of socio-ecosystems in Sierra Nevada. By quantifying some of the effects of the watering provided by these irrigation channels, the data can also help policymakers better understand how irrigation channels can mitigate the impact of climate change in the region.

Many industries in Sierra Nevada – including agriculture, tourism, cattle raising, skiing, bee-keeping, and mining – are highly dependent on this water, as are all downstream towns and villages.

UN Environment is one of many partners supporting this project. ECOPOTENTIAL, which started in 2015, uses satellite imagery, field measurements, data analysis, and modelling of current and future ecosystem conditions and services in 25 protected areas in Europe (as well as in Kenya, the Caribbean and Israel) to address climate change and other threats to ecosystems.

“New generations of satellites provide unprecedented perspectives on natural landscapes like Sierra Nevada,” says UN Environment’s Environmental Policy Expert Magnus Andresen. “UN Environment is working to ensure that governments can apply this data for effective environmental management.”


When snow melts in spring, water reaches mountain streams and percolates to recharge aquifers. Photo by Ugo Mellone
Some irrigation channels collect water from the springs and streams by the summits and deliver it to the crops, grasslands and forests below. This process slows down the hydrological cycle in the mountain. Photo by Jose Miguel Barea Aczon
The network of irrigation channels is maintained by local water managers (“acequieros”) who ensure water reaches crops and channels are maintained. Photo by Bjorn Alfthan

Climate change has already altered the hydrology of Sierra Nevada, impacting both ecosystems and communities. At the same time, land-use change is another key driver of ecosystem structure and functioning. Park authorities are now exploring how to use the ancient irrigation network to buffer the impacts of global climate change.

Most of the channels are hand-made using on-site stones and mud. This construction method makes them partially permeable to water, allowing leaking and watering of pastures below. Photo by Bjorn Alfthan

ECOPOTENTIAL is supporting the Sierra Nevada Global Change Observatory in the use of Earth Observation, while the LIFE ADAPTAMED EU project is putting this knowledge into practice by improving ecosystem management, such as planting and clearcutting forests.

In the long run, this initiative is expected to help increase the resilience of the Sierra Nevada’s remarkable biodiversity, including a total of 2,100 vascular plant species (21 per cent of European flora), which make it one of the most important biodiversity hotspots in the Mediterranean region.

Distribution of the natural hydrological network in part of the Sierra Nevada (blue) in comparison with the network of ancient irrigation channels (orange). The background image shows photosynthetically active vegetation (green), bare soil and snow (both light coloured). Diagram of irrigation channels in relation to a river by Bjorn Alfthan (GRIDA)

More about the funding

Funding for this project comes from Horizon 2020, the biggest EU Research and Innovation programme ever with nearly 80 billion euros of funding available over seven years (2014 to 2020) – in addition to the private investment that this money will attract.

For further information: Magnus.Andresen[at]un.org