Portugal dreams of the MAR

Managed Aquifer Recharge (MAR) is the targeted replenishment of groundwater reservoirs in preparation for dry times. adelphi is on a mission: to convince the countries on the Mediterranean Sea of the numerous advantages of MAR.


At first glance, it might seem like a side note to daily democratic life in Portugal: In two resolutions at the end of December 2022, the Portuguese parliament recommended that its government promote the development of projects and initiatives for artificial groundwater recharge. As a result, the method known as Managed Aquifer Recharge could become a supplementary, nature-based solution for water management in Portugal. The step represents another piece of the puzzle of climate change adaptation, ecosystem preservation, water scarcity and water security.

MAR could be especially important in areas where droughts are worsening and becoming more frequent, impacting not only people, flora and fauna, but also agriculture and forestry. Many regions in the Mediterranean are plagued by extreme heat and drought. The same is true in many places around the world with growing populations, intensifying agriculture and increasing tourism. All these affect the availability of water resources and lead to the overexploitation of aquifers. MAR may offer promising solutions to these problems. What seemed like a side note has suddenly become a sensation – at least for the AGREEMAR project team.

Meeting with the Portuguese Farmers' Association (CAP)

What is Managed Aquifer Recharge?

First, however: How does MAR technology work? Most of the time, aquifers are replenished by natural water cycles. After rainfall, for example, the falling water seeps into the soil and accumulates as groundwater. If the rainfall has become heavier and less frequent due to climate change, however, the water has little opportunity to penetrate into the soil. Instead, most of it flows directly into the sea via rivers, where it mixes with saltwater. Making this water usable again requires a great deal of energy. With MAR, this “lost” water is stored underground via near-natural infrastructure, where it can be recovered at times of high demand. There are many forms of MAR: common examples include seepage ponds, well fields, artificial streams, and bank filtration. The right type of water management depends on the circumstances (e.g. hydrogeology), the water availability (e.g. collected rainwater or treated wastewater) and on-site requirements.

Either way, MAR has many advantages. For example, in areas where a lot of groundwater is extracted, MAR can prevent subsidence. In coastal areas, it can help reduce the ingress of seawater. But regardless of where it is deployed, MAR is able to provide stored water for drinking water supply or the irrigation of agricultural land, especially in dry periods. This is what makes it so special.

The AGREEMAR project

The situation is critical in Mediterranean countries like Spain, Portugal, Cyprus and Tunisia, where water is scarce. This increasing water stress means that living organisms and plants face a higher risk of environmental problems and economic difficulties. Action is needed, and Portugal may have taken the first step. The resolutions of the Portuguese parliament are in line with the aim of the AGREEMAR project, i.e. promoting the safe use of artificial and fairly Managed Aquifer Recharge in Portugal and other Mediterranean countries to increase resilience to climate change. AGREEMAR includes six partners from universities, public companies and national research centres from Germany, Spain, Cyprus, Portugal and Tunisia as well as key players from four regional clusters in the Mediterranean region.

At the end of 2022, the project team went on a mission. In Spain, Portugal and Tunisia, they sat down with representatives from civil society to find out how and where MAR technology can be planned and implemented. From the start, the team followed a participatory approach and collaborated with stakeholders. This included farmers, operators of sewage treatment plants and representatives of environmental authorities and regional water supply companies. The needs assessment took into account the different roles, responsibilities, interests, demands, ideas and experiences. This process creates trust and promotes personal responsibility and cooperation. In addition, it helps achieve made-to-measure project results, which guarantee the sustainable use of MAR even after the end of the project.

Meeting with the project team of the National Agronomic Institute of Tunisia (INAT)

What is possible, what is feasible

In addition to new planning and management strategies, the project also focuses on implementing a governance framework for fair, sustainable groundwater management. Agreements on the equitable sharing of benefits from MAR systems are a key component on the local level. To this end, the project team sought out exchange with relevant interest groups and analysed barriers to and conflicts in the existing water supply. The agreements are based on feasibility maps, numerical groundwater models for potential MAR plants and selected demonstration sites in the Mediterranean basins. In Portugal, for example, the feasibility of MAR is currently being studied in the municipality of Comporta and at the Albufeira de Furta Galinhas reservoir.

Time will tell whether Portugal and the other Mediterranean countries will realise the dream of MAR. In any case, exemplary projects like this could pave the way for future MAR plants and increase public acceptance of groundwater replenishment. To find out which other places the AGREEMAR project team has visited in the past few weeks, visit the project website.

Assessment of the MAR site in Qurba, Tunesia

Contact: Ronjon Heim and Anika Conrad