Under pressure from climate change and overuse, a precious but overlooked resource is at risk of being permanently depleted
Life on Earth depends on water, yet preserving this vital resource is anything but straightforward. In Greece, as in many parts of the world, water scarcity is becoming an urgent concern. A growing focus of the debate is groundwater; a hidden resource often misunderstood as abundant and self-replenishing, but now at risk of serious decline in many places.
“When we talk about groundwater, our minds usually go to huge underground water reservoirs that provide us with practically inexhaustible quantities of good quality water,” explains Alexandra Gemitzi, a professor at the Democritus University of Thrace. In an interview with journalist Dimitra Triantafyllou for the Greek newspaper Kathimerini, Gemitzi highlights how far this common perception strays from reality.
Her research tells a different story. For over two decades, Gemitzi and her team have been collecting data on groundwater across Greece. Their findings are deeply troubling, revealing a steep and ongoing decline in groundwater levels across large regions. Now, Gemitzi is sounding the alarm.
She expresses concern over the public’s limited understanding of what groundwater actually is. Unlike rivers or lakes, groundwater is invisible to most people, only revealed through wells and springs. “This particularity makes it more protected but also more difficult for humans to comprehend compared to surface waters,” she explains.
Responsible water management must be based on the sustainable use of renewable reserves, Gemitzi warns: not letting the rate of use get ahead of the rate of natural replenishment. As she notes, any resource can become “non-renewable if overexploited.”
But estimating the actual rate of replenishment of underground aquifers is complex. There’s a dearth of reliable data. But Gemitzi and her team have developed innovative methods to assess groundwater recharge across Greece from 2001 to 2024, combining traditional hydrological models with open-access data sets, remote sensing, even measuring changes in the gravitational field across Greece (a proxy for unseen water mass).
The conclusions are stark. Groundwater reserves have been diminishing for years. The rate may now be accelerating. Gemitzi explains: “Beyond known spatial differences – for example, western Greece receives nearly twice as much rainfall – the data shows a gradual decline in both rainfall and groundwater replenishment, with a peak in rates over the last five years.”
This trend is driven by several factors: the rising rate of evapotranspiration (the process by which water returns to the atmosphere from soil, water surfaces and plant transpiration) due to higher temperatures and a drop in rainfall, especially the increasing number of rainless days. A few heavy days of rain aren’t sufficient.
And while there’s uncertainty about whether climate change will mean Greece has more or less rainfall in the future, higher temperatures – and therefore higher evaporation – are highly likely. Less snowfall and snow thickness in the Greek mountains is also a factor.
As Greece faces a hotter future, understanding and protecting its unseen water reserves is not just a scientific issue, it’s a societal imperative.
Original article (“Η «αόρατη» υποβάθμιση των ελληνικών υπόγειων υδάτων”) by Dimitra Triantafyllou was first published in Greek on 26 June 2025.
It’s available here.
Kathimerini is a daily political and financial newspaper based in Athens, Greece.
