Costing the earth: who’s responsible?

17 November, 2014 by (comments)

Quarry site in Tana’s River Basin. Research shows quarrying adds to soils sediment loads in the watershed.

Wielding a hammer, John Kabola steps back and surveys his day’s work. The quarry cut into the hills of Kenya’s Upper Tana watershed reveals deep layers of earth like a sliced cake. Quarry stones are in demand – the construction industry is thriving.

That’s good news for Kabola, who has risen to quarry operator, investing his income in a coffee farm. “I started generating money to educate my children. This job has been important all the way through,” he said. But at what environmental cost?

Instead of the hours it takes to bake a cake, cooking up a landscape takes years – thousands. And as the icing is usually best, the top layer of soil is the most precious and fertile.

Recent research shows that quarrying creates pathways which flush rain water – and fertile top soil with it – down Kenya’s largest 1000km long Tana River. In the last 10 years, sediment yields have jumped more than 30 percent.


CIAT researchers Fred Kizito and Kennedy Ng’ang’a with George Njugi, from The Nature Conservancy in Kenya, testing the water for soil sediment.

Fred Kizito, CIAT’s Nairobi-based soil expert, says the study highlights the urgent need for an inclusive decision-making process which takes all users of the Tana River ecosystem into account. “Farmers, road builders, quarry workers, downstream users – a holistic solution needs everyone involved,” he said.

Kabola knows about soil erosion and its impact on farming: he’s also a coffee farmer after all. As he gathers his jacket for the walk home, he waves his finger with conviction. “Let it be clear. We want our children to meet this place better than we met it,” he says. “We don’t want a desert here next century.”

Taking root: A fierce incentive

Reforestation efforts are essential to working the quarry, he says, showing visitors around a nursery of trees. Next to him is Priscilla Ngacha: the gently spoken eco-warrior with an infectious laugh, who, with her team of “Green Rangers,” is transforming degraded landscapes including old quarries, encouraging communities to dig terraces and plant nitrogen-fixing grass or trees.

She knows more than most about reforestation, belonging as she does to the Green Belt Movement, founded by former Kenyan Noble Peace Prize Winner Wangari Mathai. “When I first came here, I found few trees,” she says, rifling through potted seedlings to find the best specimens. That’s changing now.


Priscilla Ngacha of the Green Belt Movement: encouraging tree planting for greater biodiversity.

What do Ngacha and Kabola both have in common? They’re part of a bigger picture initiative to tackle landscape degradation. As CIAT’s Geospatial Analyst, Kennedy Ng’ang’a explains, soil and water are inextricably linked in a watershed. “At landscape scale, we stop looking at individual farms and think about their mosaic.  The water balance has a fundamental impact on soil resourcefulness,” he explains.

The Nature Conservancy, CIAT and others have generated maps representing what’s happening from the ground up. Using complex soil data calculated for each soil type found in Tana’s Upper watershed, hydrological and land use change data, the maps are updated regularly to track developments.

It’s not dirt cheap… 

Meet Faith Mbathi. A surface water officer from Kenya’s Water Resource Management Authority, she has a sharp eye for accuracy and a fortunately daring approach to wading through the waters of the Tana River. Her job is to collect regular flow and quality samples, indicating soil sediment in the water.

Her data guides users like Nairobi City Water and Sewerage Company, which supplies over 95 percent of Nairobi’s drinking water. The company spends 40 percent more during the rainy season, cleaning soil sediment out of water clarifiers, says plant coordinator Peterson Thairu.

That adds up. Not only does cleaning cost more in labor and imported chemicals; intensive cleaning slows water treatment and reduces flow. KenGen, which supplies 70 percent of Kenya’s electricity, complains of reduced water flow for hydropower generation, which sometimes means switching to expensive thermal alternatives – with consumers picking up the tab.


The Tana River serves millions of people along its 1,000km stretch.

Sharing benefits; sharing responsibility

It will be a first for Africa when it’s launched next year. All eyes – and a lot of money – are rested on it. The Nature Conservancy’s Fred Kihara, spends his days putting the final touches on it: a solution piloted since 2012 in the form of The Nairobi Water Fund.

It’s already worked in Ecuador, where The Nature Conservancy’s Water Fund started with US$21,000 is today worth more than US$10 million. The fund is a solution where big downstream users – companies, industries – financially and technically support watershed “keepers” like Kabola to manage and keep the watershed clean.

Guided by maps and soil data, members of the Fund can make informed decisions about where and how much money to invest. “We need good science to determine major areas to treat, and to make the private sector aware that water – their raw material – is under threat”, said Kihara.

“I’m very excited, and it’s not just me,” he said. “In the first two years, we’ve raised US$900,000, supporting 5,000 land owners upstream to conserve soil and water, improving water use,” he said. It’s not dirt cheap – but a glass of clean water shouldn’t cost the earth. That’s everyone’s responsibility.

Download the Water, Land and Ecosystems program report.

Photo credit: Georgina Smith / CIAT

Meet the protagonists of this initiative in our 5-minutes photofilm


Tagged With: , , , , , ,
Filed Under: Africa @en, Climate Change, Soils, Soils website