29 November 2016

STW Open Mind

Bacteria could save us from extreme drought

Ruud Schotting (l) and Amir Raoof (r) receive their grant.

In order to avoid extreme dry periods, naturally occurring bacteria in soil could save large amounts of water: it could help millions of people in poor areas. Earth Scientists Ruud Schotting (Sultan Qaboos Chair of Quantitative Water Management) and Amir Raoof from Utrecht University received an STW Open Mind grant to develop this simple, but unconventional idea.

During dry periods many areas on Earth experience a scarcity of drinking water. In places with a dry climate where trickles of groundwater are already in short supply, water can easily seep into the soil disappearing deep into the earth through fractures in the crust. If these cracks were sealed, the shallow bottom could act as a huge drinking water reservoir allowing water to be easily pumped out.

A plug in the crack

The easiest way to keep the water available and out of the cracks is to place a plug in the fracture, just as you would in a sink, which would make a natural waterproof basin. Utrecht University Geoscientists Ruud Schotting and Amir Raoof have devised a simple but unconventional method using soil bacteria, which they explain in the following video.

Cultivating bacteria colonies

It’s a simple idea: bacteria thrive in nutrient-rich environments. A substantial bacterial colony would be large enough to close the gap and to act as a plug. During periods of rain, the scientists spread considerable amounts of nutrients the ground on which bacteria thrive. The colonies seep through the soil and into the cracks acting as a natural seal. The normal flow of water assists the growing colonies, which will naturally move toward the fractures clogging them in the crust.

Testing in Limburg

“With this grant we can extensively test whether this principle works”, says Schotting. “Our plan is to dam off an area of 15 by 15 metres. This will give us a test environment that we can control and for which we can exclude external influences. We can feed the bacteria already present using nutrients, and then measure the level of the groundwater at regular intervals. If the water level does not drop any further, then we know that our experiment is successful.”