Indonga, donga, gully, gutter — all describe the same thing — the seemingly unstoppable washing away of precious top soil down a cruel rent in the ground.
Dongas are intensified by climate shift which brings down heavy sudden deluges, creating dreadful, roaring chocolate rivers sweeping away all life where once was a dry, gouged, earth — none of it good.
Arthur Mabentsela, a boy from Khayelitsha, Cape Town, who grew into an accomplished 36-year-old chemical engineer, metallurgist, lecturer and publisher of research papers, has personal beef with dongas.
They have taken 30% of the iintsimi, the arable land back in Nqamakwe, home of his parents, grandparents and his ancestors.
Cape Town, he says, is “a commercial space that does not carry the family signature. My parents are from Nqamakwe, which makes it my home”.
Dongas are a “slow, horrifying threat to land use. Travel along the rural parts of SA and you will come across scorched pieces of land which seem to expand indefinitely with no help in sight”.
Technically speaking, dongas “are open channels in the soil deeper than 30cm caused by concentrated surface water running down a hill”. They threaten homes and food gardens, grazing and croplands.
“SA has no unified indigenous solution to restore existing gullies.”
He intends to change this.
Mabentsela, founder and director of Fakade Drip Pace Engineering Solutions, said he had engineered an “indigenous gully restoration solution” using alien trees and recycled Chibuku sorghum beer cartoons to build check dam walls across the dongas.
“These check dam walls help slow down the surface runoff water and retain eroded soil.”
The walls are being put to trial in a 57m long, 4m-wide, 3m deep donga at his home village in Nqamakwe. He called it “a small gully that is safe to trial the solution on”.
He said his education, work experience and now research was how he prepared himself to carry out engineering research which would “change Southern Africa”.
Mabentsela said the Eastern Cape was the province second-most affected by gully erosion behind the Northern Cape at a time when the country was short on knowledge and agreement on how to restore gullies, or even “whether gullies should be restored in the first place”.
He explained his company’s check method, which was to “use a series of walls built in the gully to slow down the flowing water that erodes the soil. The walls, together with planted vegetation, hold back the land carried by the water”.
Log check dams built with machines were the cheapest and most effective, but large indigenous trees were not an option and machining costs were high.
“Our technical the team, with support from our general manager and a marketing manager, engineered a solution that makes use of the alien and invasive Australian dywabasi tree (black wattle) to build check dam walls and then use empty Chibuku cartons to form a curtain over the dywabasi wall that will provide a near watertight wall.
The solution is low cost and relies on volunteers.
Suddenly a poor rural area of the Eastern Cape has a highly qualified expert working on their land restoration.
Mabentsela obtained his degree — pipped to the post as the hardest course by actuarial science — at UCT in 2010 and went on to earn a Masters in extractive metallurgy from Stellenbosch University.
He is busy with his doctorate on the application of fracture mechanics in ilmenite freeze linings.
This is high-value chemical engineering work.
Ilmenite, the most important ore in titanium, is vital in the manufacture of paint, printing inks, fabrics, plastics, paper, sunscreen, food and cosmetics.
But the slag or waste produced during ilmenite smelting is so corrosive that the smelters need to be operated with a freeze lining.
He also spent three years working as a metallurgist and seven years as a chemical engineering lecturer.
However, all of these were done “to equip me with the skill to carry out engineering research to change Southern Africa”.
“In 2022, coming back from Botswana I decided to open my own engineering company that seeks to use formal research methods to solve and commercialise solutions to problems that trouble Southern Africa and the world as a whole.
“Oh yes I am bipolar too. So to anyone who lives with the condition, let them know you can live and function with bipolar.”
He chose to work on a solution to donga erosion in Nqamakwe “because it was known territory, which limits terrain uncertainty and politics”.
“Gullies are real. As an engineer you have to think these things through.
“Funny enough, I developed a teamwork course while lecturing. Because team dynamics hinder engineering work.”
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