Increasingly accurate groundwater reserve estimates 

It is estimated that in 2050, 25% of the world’s population will be living in areas affected by a lack of drinking water.

Text Marianne Mustonen Illustration Timo Lähivaara and Jari Kaipio

Traditionally, groundwater reserves are explored by drilling a set of wells – a method that is often prohibitively expensive and difficult to implement in developing countries. An alternative method for estimating water reserves is based on data obtained from seismic waves.

Researchers from the University of Eastern Finland took part in a survey carried out by the Geological Survey of Finland, the University of Turku and the University of Uppsala, seeking to analyse the groundwater area in Virttaankangas, Finland, with the help of seismic soundings. In the soundings, a drop hammer was used as a seismic source, and the seismic waves generated were captured by a network of accelerometers.

The data from the soundings is being analysed at the Department of Applied Physics. The objective is to estimate groundwater reserves with the help of computational models that are modern and accurate, but still somewhat heavy to use.

“Groundwater is stored in porous aquifers, and the propagation of seismic waves depends on unknown aquifer properties such as density and porosity. This data can be used to estimate groundwater reserves, among other things,” says Senior Researcher Timo Lähivaara.

However, using this method to estimate the cubic capacity of groundwater reserves is a major computational problem.

“The significance of uncertainty modelling hasn’t been fully acknowledged until recently,” says Professor Jari Kaipio from the Department of Applied Physics. He spends most of his time working in New Zealand.

There is plenty of water in Finland, but elsewhere in the world, the sufficiency of water is a major issue.

“In New Zealand, for example, the use of groundwater is strictly controlled. When the usage of groundwater is determined, it is first authorised to be used by humans. If the reserve is sufficiently large, it can be authorised to be used as drinking water for animals, and only lastly as irrigation water,” Kaipio says.

In 2013, dairy cattle worth millions of euros had to be slaughtered in New Zealand because the authorities couldn’t be sure about the sufficiency of water.

“By using the methods we are studying now, it is possible to carry out measurements above ground by using inexpensive seismometers, which are acceleration sensors,” Kaipio says.

Uncertainty modelling is also being carried out at the university in the remote sensing of forests, medical imaging and climate change modelling, for example.

“I believe that in the future this line of research can also find applications in the analysis of bone and cartilage porosity,” Lähivaara says.

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