Eawag Annual Report 2021
The Annual Report gives a wide-ranging account of current Eawag projects. It is published in English and German, and since 2013 also in French.
The Annual Report gives a wide-ranging account of current Eawag projects. It is published in English and German, and since 2013 also in French.
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RESEARCH<br />
15<br />
Noble gas analysis sheds light on groundwater flows<br />
A recently developed method can provide a better understanding of groundwater.<br />
Tests carried out in Emmental showed that a large proportion of the groundwater<br />
comes from the River Emme – and that travel times within the aquifer are much<br />
shorter than previously assumed.<br />
Switzerland’s aquifers store around 150 billion cubic<br />
metres of groundwater. These vast water resources<br />
are of immense social, economic and natural value. For<br />
example, groundwater accounts for roughly 80 per cent<br />
of our drinking water. Hydrologist Andrea Popp says,<br />
“If we want to ensure secure water supplies, we need<br />
from the Emme river – and that the water travels<br />
relatively quickly underground. “We can think of Emmental<br />
as a bathtub largely filled with sandy gravel,”<br />
says Popp. This explains the travel times of just 7 to<br />
14 days.<br />
Andrea Popp, <strong>Eawag</strong><br />
Photo Fieldwork in the<br />
streambed of the Emme<br />
at Aeschau.<br />
to understand how surface water and groundwater<br />
mix, and how quickly water travels through aquifers.”<br />
Like a bathtub filled with gravel<br />
For her doctoral thesis at <strong>Eawag</strong> and ETH Zurich,<br />
Andrea Popp developed a new approach to improve<br />
our understanding of groundwater: together with Rolf<br />
Kipfer, Group Leader at <strong>Eawag</strong> and Adjunct Professor<br />
at ETH Zurich, and other scientists, she conducted insitu<br />
measurements of dissolved noble gases, using a<br />
portable mass spectrometer. The results of this analysis<br />
were combined with modelling to track groundwater<br />
flows through the aquifer.<br />
Identifying risks to water supplies<br />
These results are important not least in the context<br />
of climate change, as the Emme’s annual discharge<br />
declined by 20 per cent between 1999 and 2018 – and<br />
is likely to decrease further in coming decades. Popp<br />
concludes, “Our approach can highlight the risks and<br />
vulnerabilities of drinking water supplies, thus helping<br />
to improve water resource management.”<br />
In the Emmental case study, the new method showed<br />
that around 70 per cent of the groundwater infiltrates
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