Geologist warns of impending dry boreholes in Nairobi

A street child drinks water from wash basins installed along Tom Mboya Street in Nairobi's CBD on August 08, 2020. [Courtesy]

A geologist has warned of impending dry boreholes in Nairobi City due to the depletion of aquifers.

This is due to many boreholes that have been dug and continue to be dug deeper in the city to get groundwater.

In 2016, Nairobi County reported 4,000 illegal boreholes that had been dug without authorisation from the supervising authority which is the Water Resources Management Authority (WRMA).

The report stated that out of about 6,000 boreholes in the city, only 2,000 were in the WRMA’s borehole database system.

“The question is, are we willing to face a crisis or not? When you deplete your aquifers faster than what is coming in, the pores of that rock that holds water collapse and you get less and less storage,” said Prof Daniel Olago, Kenya Country Director, REACH Programme.

Prof Olago, who is also Director at the Institute for Climate Change and Adaptation at the University of Nairobi (UoN), was speaking during a media breakfast in Nairobi last week that also saw the launch of ‘REACH: Improving Water Security for the Poor’ programme.

The media breakfast, themed ‘Improving Water Security in Kenyá Drylands in Light of Climate Change’ was organised by REACH Programme in partnership with Kenya Editors Guild (KEG) and Kenya Environment and Science Journalists Association (KENSJA).

The professor said Nairobi has a multi-level aquifer system and excuses that borehole drillers are digging the boreholes deeper and deeper will not be sustainable.

“Now many of the boreholes are beyond 300 metres but you cannot drill until you reach the centre of the earth thinking you will always get water. Underneath these piles in which we are getting water are volcanic rocks,” said Prof Olago.

He added: “Beneath those volcanic rocks we have what we call basement system rocks. These arevery old impervious rocks and, in Nairobi, they lie at 400 metres, plus or minus a couple of tens of metres depending on where you are. And this will be the end of groundwater in Nairobi so, actually, in my mind, we are already targeting the last level of aquifer in Nairobi.”

He said what is going to happen soon is that there will be compressed aquifers, thus storing less water since much more water is being extracted than it should.

“And at the end of the day, Nairobi will be a place where we cannot rely on groundwater anymore because we are going to have dry boreholes,” he said.

Prof Olago said we can avoid the situation of dry boreholes if we do the right thing because the Water Resource Management Authority(WARMA) alone cannot police all the drilling of boreholes, due to the personnel capacity.

“It’s now up to us, when you get a permit that tells you that you can target only this aquifer and leave the others alone, you do the right thing. If they tell you this is the only amount you can abstract, don’t come and put in another pump and over abstract because groundwater systems are interconnected,” he said.

Prof Olago added: “While you think you are doing well for maybe your apartment by over-abstraction, everybody will lose out in a year or two and it’s very important to adhere to regulations which are based on science and not anybody’s whims.”

He called for the completion of the Northern Water Collector Tunnel, which he said would supplement water demand in the city.

He also called for funding of aquifer studies for groundwater exploration in the country to inform where to dig boreholes to provide water in a country where 40 per cent of the population has no access to clean, safe drinking water.

“Instead of spending millions drilling boreholes that can end up without water, why not fund aquifer studies first?” he asked.