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Invisible groundwater: a critical resource with visible impacts

Making the invisible visible is the motto of the United Nation’s World Water Day for 2022. It celebrates groundwater, the largest reserve of freshwater which accounts for 97 per cent of all freshwater available on earth and provides drinking water for 50 per cent of the global population.

About 75 per cent of EU inhabitants depend on groundwater for their water supply which is also a crucial resource for industry and agriculture. Around 43 per cent of all the water used for irrigation come from groundwater.

Groundwater feeds rivers all year round. It maintains wetlands and acts as a buffer through dry periods. According to the Europen Commission’s Directive on Groundwater Protection, more than 50 per cent of the annual river flow is derived from groundwater while in low-flow periods, more than 90 per cent of the flow come from it. With all this in mind, it’s easy to understand what impact groundwater deterioration could have on aquatic or on terrestrial ecosystems.

Pressures on groundwater and remediation

With the intensification of industrial activities and agriculture, however, pollution levels of groundwater increase and last for decades. As a result, the restoration of contaminated reserves and sites becomes very difficult.

“[…] The experience of remediation of the past 20 years has shown that the measures taken have in most cases not been able to completely remove all contaminants and that pollutant sources, even if partially removed, continue to emit for long periods of time,” informed the European Commission.

Nevertheless, remediation can restore, for instance, high-risk brownfields that represent the sources of groundwater and surface water pollution by toxic substances and heavy metals that have been released by past industrial, military, mining, transport and agricultural activities.

Konstantin Ivanov, the Regional Coordinator at the Global Water Partnerships (GWP) Central and Eastern Europe who argues that the CEE needs better water policies, has pointed out that only in Slovakia there are more than 1,800 brownfields. According to him, remediation of these sites should be funded by special financial instruments in the EU.

“This is an opportunity to establish applied research groups to find innovative solutions for brownfields remediation,” he said.

Around 25 per cent of all groundwater bodies across Europe have poor chemical status, the European Environmental Agency reports. Caroline Whalley, water industries and pollution expert at EEA tells CEENERGYNEWS what threatens groundwater in Europe and what countermeasures could be taken.

“Our assessments show that the main pressure on groundwater quality is nutrient and pesticide pollution from agriculture,” she says. “The data clearly show that we need to do more to manage water resources sustainably in Europe and the European Green Deal puts focus on this. Reducing pressures from agriculture and public water supply play a key role in this but new approaches are also needed, including the use of information technology, financing and more circular use of water.”

Groundwater depletion is another risk posing the health and availability of this essential life source. The causes range from climate change and resultant shifts in precipitation or snowmelt patterns to human use such as withdrawal of groundwater and even pumping too much water into the ground for oil and gas extraction which leads to erosion and ecosystem balance alteration.

What are the links between groundwater and energy?

Even if it does not seem so clear at first, the links between groundwater and energy are multiple. To put aside the most obvious hydropower which is based on water reserves of rivers that themselves are fed by groundwater, the interaction of groundwater and energy arises in multiple ways. Take geothermal energy, nuclear, and shale gas, as an example.

Geothermal, an important renewable energy source that contributes to achieving net-zero emissions uses groundwater. A British Geological Survey informs that in conventional hydrothermal systems, the heat is usually transported by natural groundwater, circulating within deep aquifers. It is exploited via a doublet system consisting of two deep boreholes drilled over a range of depths down to 5 kilometres where one is for abstracting the hot water and the other is for re-injecting the cooled water back into the geothermal system.

Strikingly, nuclear plants can be sources of groundwater contamination. The subsurface that becomes a repository of materials arising from energy production processes, such as radioactive waste from nuclear power generation and carbon dioxide from combustion-powered electricity generation, pose a risk to groundwater.

Even though Europe does not produce shale gas, this relatively novel source of natural gas raises concerns about the hazards to groundwater too. Pathways for contamination of both groundwater and surface water in the vicinity of shale gas sites include spillages of chemicals and migration of fluids from the shale rocks.

Considering all the above, in light of the climate crisis and the European Union’s Green Deal ambitions that reiterate the need to manage water resources sustainably, the critical role of groundwater protection comes to the forefront.

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