Water retention landscape to restore the water cycle and reduce vulnerability to droughts (Tamera, Portugal)
The Climate Challenge
Tamera, a farm of 154 ha, is located in Alentejo, the most arid region of Portugal. Erosion and desertification have progressed so rapidly and extensively in the area that the humus topsoil has disappeared. This humus soil layer, which was shaded and rooted by plants, is fundamental to soaking up the rainwater and thus giving the water time to seep into the deeper ground layers and fill up the underground aquifers. Thus erosion and desertification threaten the ability of the Alentejo ecosystem to deliver key services, such as water purification, agriculture productivity and drought prevention. Climate change is expected to exacerbate these trends.
The Adaptation Response
Tamera has managed to counteract such trends of increasing erosion and desertification through the creation of a “Water Retention Landscape” (WRL) comprised of a system of lakes and of other retention systems, and also including other structures such as terraces, swales and rotational grazing ponds. This approach to water management has created a regenerative basis for autonomous water supply, the regeneration of topsoil, forest, pasture and food production, and greater diversity of wild species.
The People and Institutions Involved
The project was opened and discussed with the population of the region. Cooperation from neighbours has been important in several of the building stages.
The Outcome of Action
In Tamera, the creation of lakes has proven to be a faster and more effective method to reduce erosion than reforestation, which is a much slower process. It was used as a first step to allow for reforestation in the most eroded areas. From 2006 to 2015, 29 lakes and retention spaces were created using local earth and stone materials, which increased the area of water bodies from 0,62 ha in 2006 to about 8,32 ha. Tamera is now prepared to fully absorb even strong continuous rainfall. This large retention area is located at the highest point of the valley. The water pressure is therefore high enough to irrigate all of the land, without additional energy needs for pumping. The water retention landscape creates space for riverside forest plants and fruit trees as well as provide a protected path for wild animals to reach the lakes and ponds.
Coordinator of Education and Research
Tamera - Peace Research Center
Monte do Cerro, Portugal, 7630-303 Colos
The full report of this case study can be read here.
Photo © Tamera - Peace Research Center