Tue, Jul 03, 2018 - Page 9 News List

Kenya takes a look into the unknown: its groundwater reserves

By Isaiah Esipisu  /  Thomson Reuters Foundation, UKUNDA, Kenya

The sparkling seas that lap the miles of sand along Diani beach have made this corner of southeastern Kenya one of the country’s main tourist attractions.

Yet few visitors would know that all the water in their taps comes from boreholes sunk into aquifers — underground reservoirs of freshwater that are also used by residents, businesses and agriculture.

Wellwater means life, said Mary Wanjiru, who manages the Rongai Roasting House, a restaurant in the nearby town of Ukunda, about 30km south of Mombasa. “Without it, life will be totally unbearable in this town given that there are no permanent rivers or freshwater springs.”

However, until recently, water users — and experts — had little idea how sustainable that water supply might be, a particular worry as climate change brings worsening droughts.

The problem is a widespread one across Africa, where little is understood about groundwater supplies, University of Nairobi geology professor Daniel Olago said.

Even basic information — how much water they hold, how their supply replenishes and how they respond under different climatic conditions — is sparse.

“We do not know what we have because we have not done adequate studies on groundwater,” he said.

However, over the past two years that has started to change.

Scientists from the University of Nairobi, the University of Barcelona, Oxford University and the Jomo Kenyatta University of Agriculture and Technology have been studying the groundwater system in Kwale County, with the Msambweni aquifer that supplies Ukunda as their main focus.

That has allowed them to determine the aquifer’s size and depth, as well as the geochemistry of its water. A computer program then flags risks linked to water quality, quantity and demand, as well as the area’s economic and social conditions.

They can then model projections for different scenarios based on aspects such as climate or how much water is extracted.

“Lack of adequate information is a common problem throughout the country,” said Olago, one of the lead researchers in the study known as Unlocking the Potential of Groundwater for the Poor.

“We need to know how much of the rainwater is being recharged through rainfall and infiltrations, how much of it is stored and so how much of it can be sustainably used,” he said.

The findings mean that the researchers also know whether aquifer water is suitable for drinking — as the study showed Msambweni’s is — or whether it should be used for industry or irrigation.

Two of the largest users of water in Kwale are mining company Base Titanium and Kwale International Sugar Co, which has 8,000 hectares of sugarcane under irrigation.

Both have dams — and are building more — and both draw from the Msambweni aquifer during times of low rainfall; however, the study shows that their use has not had a large effect on groundwater levels.

The scientists worked closely with the two companies, not least as they have extensive knowledge of Kwale’s groundwater, said Calvince Wara, research operations manager for Rural Focus, a local water consultancy that is involved in the study.

Once the system is well understood, it would be possible to identify the best way to use the water sustainably, Wara said.

The government simply issues borehole licenses to companies that want them, but it typically does not know an aquifer’s size, its replenishment rate or its response to the climate — all key indicators of how long the water might last, he said.

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