Getting to the root of erosion: Planting indigenous trees halts river bank collapse
Intaba Environmental Services Water Stewardship Project
Runner-up: Biodiversity Stewardship Award
Moving invasive species from rivers may immediately provide more water, but, says Johann van Biljon of Intaba Environmental Services, the shallow root system of the trees wreaks havoc with soil erosion.
“One big eucalyptus takes 200 litres of water a day,” he explains. “But when the tree is gone, the floods come and instead of side erosion taking place, the water goes deeper into the soil. Subsequently the water table drops and more and more sediment collects downstream.”
This is where Intaba Environmental Services steps in.
By building up the riverbanks with indigenous plants, erosion is controlled. Some plants even take up sediment and provide pockets for fish, birdlife, insects and further ecological functioning.
Intaba has been propagating indigenous species for over seven years and through specific genetic testing, plants are matched to particular biomes.
“Essentially we provide an ecosystem restoration programme,” says Van Biljon.
The current three-year Water Stewardship Project is managed by Intaba and funded by the departments of environmental affairs and agriculture in the Western Cape and Living Lands, in partnership with private landowners.
To rehabilitate the riparian river zones along the two biggest rivers in the Western Cape — the Berg and Breede Rivers — Intaba aims to introduce 100 000 indigenous plants per year over the next three years.
The aim is to assist private landowners to return their land bordering these very important rivers back to its natural state, thereby improving the ecological functioning of the rivers, flood attenuation, bank stabilisation, water saving and reduced erosion.
“These rivers sustain rural and urban communities and the water quality and quantity is influenced by the health of a river’s ecosystem through which it passes,” says Van Biljon.
Additionally the project provides skills training and will provide up to 4 000 new jobs.