Between the large karst springs of the Balkan coast and the rich aquifers of northeastern Italy, water has always been abundant around the central and northern Adriatic. Now, however, this wealth can no longer be taken for granted. An age-old problem like overexploitation is especially aggravated on the coasts, invaded by thousands of tourists especially in the summer season, when heat and drought are more frequent. Depleted aquifers are increasingly struggling to counteract the infiltration of saltwater, posing serious risks to agriculture. All this is compounded by often aging infrastructure, widespread waste, and ineffective management.

To address these challenges, European cohesion policies support various projects. Some focus on governance and network modernization; others, like Blue Recharge, focus on research and innovation, starting with the most important place to conserve water: the ground beneath our feet.

Recharging aquifers: the underrated solution

Dams and reservoirs are the most common way to store water, but not the only one. Alongside these ancient and invasive techniques, there is a much more economical and less impactful one: managed aquifer recharge (MAR). The principle is simple: store excess water underground during certain periods of the year (in Mediterranean climates, in autumn and winter), creating a reserve from which to draw when it is scarce, namely in spring and summer.

Aquifers can be recharged in several ways. Infiltration basins are permeable surfaces, often created in agricultural or natural areas and crossed by channels that allow water to slowly infiltrate into the subsoil or channel it into dedicated tanks. In other cases, well systems are used, which can facilitate the infiltration of water from rivers or allow direct discharge into the aquifer. Depending on the characteristics of the terrain, surface water, rainwater, or even treated wastewater can be used.

MAR has been known since the 1950s and is widely practiced in several countries where water availability is crucial, from Australia to Israel. Until now, however, it has been almost ignored in this part of Europe (in Italy, there are notable exceptions in Veneto, Emilia-Romagna, and Tuscany). Behind this “oversight,” the FAO warned as early as the 1990s, lies a paradox: the low costs and substantial invisibility of this technique – its very strengths – make it unattractive to politicians and businesses.

The Blue Recharge project, implemented as part of the Interreg Italy-Croatia programme and running from 2024 to summer 2026, aims not only to make MAR more efficient, but also economically sustainable. With a budget of €1.9 million and led by the city of Dignano, Istria, it involves public and private partners from both countries. “We want to create a virtuous cycle of water management by promoting MAR through voluntary, but incentivized processes,” summarizes Sergio Calò, director of the project partner Venetian Cluster, which brings together businesses and research institutions in the fields of cultural and environmental heritage.

Potentials and solutions

On the Italian side, the project’s pilot site is the Mezzano Valley, a former wetland served by the Canale Emiliano Romagnolo (CER), a key infrastructure for Italian agriculture and a testing ground for high-tech irrigation practices.

The Istrian context is different, with its karst terrain rich in water but almost devoid of rivers, and where the population swells in summer due to tourists.

Since water flows through fractured rocks rather than through loose soils capable of filtering it, the risk of pollution is always real, which is why in-depth studies were necessary. “After numerous tracer tests to verify the infiltration rate and contact with the rock,” explains researcher Bojana Hajduk Černeha, “we can say that recharge is safe if supported by rigorous analyses.”

This opens up the possibility of strategic use in this area: countering the problem of seawater intrusion, which is increasingly common with aquifers depleted by excessive abstraction and rising sea levels. “We have demonstrated that the soil purifies water, even treated wastewater, enough to increase groundwater pressure and prevent this phenomenon,” assures Hajduk Černeha.

“One of the main challenges is that the concept of MAR is not directly recognized in Croatian legislation, but we have already initiated this discussion with the relevant authorities to clarify the regulatory process,” explains project manager Saša Moharić of the municipality of Vodnjan.

Among the implemented solutions is a system of canals with a filter substrate, which increases infiltration during storms and heavy rainfall. For the project, Moharić continues, water management must complement other nature-based solutions. Therefore, approximately 30 lovke, traditional clay-bottomed pools that served to create small basins in a karst area, will be restored.

Blue credits

To incentivize MAR, Blue Recharge is working on a market-based credit system similar to carbon credits: in simple terms, a “blue credit” could correspond to one cubic meter of water reintroduced into the aquifer. In practice, however, it is not simple: “CO2 is a single factor and relatively easy to calculate, but water involves several sectors: agricultural, industrial, civil, with multiple managers and disaggregated data,” Calò comments.

For this reason, Blue Recharge, continuing a multi-year journey developed in other projects such as the LIFE “Svolta blu” (Blue Turn), is working on advanced certification systems to quantify the actual benefits of individual recharge projects.

The positive effects of MAR are not limited to water storage: transforming an agricultural field into an infiltration wetland or a forest creates habitats rich in biodiversity and pleasant for people, and encouraging slow infiltration can reduce pollution. These co-benefits, Calò explains, can make the credits more attractive on the market than a simple technical operation of pumping into a well.

To quantify them, the partners aim to develop an entire technological chain ranging from hydrogeological and environmental analysis to artificial intelligence, all the way to blockchain technologies. The latter aim to make each credit, which is assigned a unique code, fully traceable, thus making greenwashing more difficult by preventing double-selling or over-counting.

The blue credit exchange platform has already been tested for the Italian side. “Now we are trying to transfer this knowledge both nationally and internationally,” adds Cosima Trevisanello of Venetian Cluster. The Italian-Croatian project has produced guidelines for replication at the European level, with the aim of creating shared standards for future EU water policies.

But there are challenges. “In a time of energy emergency, we cannot expect mechanisms like this to become mandatory: they would entail new burdens that would be difficult to accept, so we need to focus on incentives,” Calò comments, adding that, even after the project is concluded, this is the main theme the group will continue to work on.