Every drop counts

Juuso Tuure set up a test field in Maktau, Kenya. Funded by the Academy of Finland, the project studies rainwater harvesting in agriculture.

 “It’s on the equator, so it’s very hot. And red. The soil is red sand, and it has made the concrete on the houses reddish in colour,” says researcher Juuso Tuure about the small town of Maktau in Kenya.

Maktau is fifty kilometres from the University of Helsinki’s research station in the Taita Hills, near the Tanzanian border. On a clear day, you can see Kilimanjaro. Geography and geoinformatics researchers and bioscientists have been working at the station in 1989, but it was not suited for Tuure’s research. It’s too rainy.

Luckily the foreman of the station, Mwadime Mjomba, lives in a drier area in Maktau. His farm, with a cornfield, chickens and goats, was the perfect place for a rainwater harvesting experiment.

In February 2016, Tuure and the inhabitants of Maktau established a test field. They spread different kinds of white and black plastic sheets on frames to harvest rainwater. The ground was covered with mulch and with more white and black plastic sheets.

 “People who had been there before said that we should bring everything from Finland, even tape and screws. When we started, the area didn’t even have electricity, just solar panels on the roof.

The experiment went well despite the circumstances. Unfortunately they couldn’t collect quite the amount of dew the researchers expected – the average catch was 0.1 millimetres of dew water for each square metre of the collection area per night.

On the other hand, covering the ground with white plastic proved to be useful. The white covering collected dew while evening out the highest heat peaks and reducing the evaporation of moisture.

 “Dew harvesting won’t solve water problems, but it can promote survival in dry and remote areas,” Tuure says.

 “The good news is that affordable PVC and PE plastics were as effective at harvesting dew as the more expensive OPUR plastic specifically developed for the harvesting.

This article was published in Finnish in Yliopisto magazine 10/2016.