Divining success

The world’s rapidly growing population and associated expansion and intensification of agriculture means groundwater contamination is becoming a global issue, says Portfolio 2 leader Ian Woodhead.

Portfolio 2: Agri- and environmental technologies

In some parts of the world groundwater is a significant source of drinking water. It has been estimated almost half of all Americans depend on groundwater for their domestic supply.

Although groundwater it is the dominant vector for contaminants such as nitrates from agriculture, heavy metals from mining and even radioactive isotopes from industrial activity, an effective and accurate method for mapping groundwater flow has yet to be developed.

“At the moment the way people find out where and how fast groundwater is moving is by putting down wells,” says Ian.

Ian and his team are developing a new way of measuring groundwater flow using a cluster of techniques they have dubbed “inverting electromagnetics”.

It will involve using electrodes to sense the velocity of groundwater from faint Faraday signals, which will eventually be used to develop products that present data in easily understandable ways. This is something that will be invaluable for end users including water resource managers, farmers, and regulators, says Ian.  

In keeping with the Challenge’s approach, the science and engineering is not easy.

“There is a reason that this problem has not yet been cracked. We are really pushing the bounds of understanding when it comes to generating large magnetic fields and measuring weak signals while eliminating disruptive background noise.”

To solve some of these tough problems the Challenge has brought together many of New Zealand’s pre-eminent minds in mathematics, physics and engineering.

Their first step is to undertake a trial at the University of Canterbury where they plan to set up a small-scale model of an underground aquifer to which the team can apply an electromagnetic field and set up a system of electrode sensors. Ian says they will set up the model over the coming months and hope to have some results by early 2017.

He has had preliminary discussions with a local Iwi about a larger scale physical trial in an environmentally sensitive coastal area where groundwater and seawater interact.