Hydrological effects of revegetation on hillsides

Hydrological effects of revegetation on hillsides in the Baviaanskloof, South Africa

Carried out by
Marjan Sommeijer

South Africa

Background research

Marjan Sommeijer travelled to Baviaanskloof in South Africa in 2010 to conduct research for her placement as part of her Bachelor’s degree in International Land and Water Management at Wageningen University.

The Baviaanskloof is an extremely arid and heavily degraded area as the result of farming. This means it is hard for the soil to retain the little rainwater that falls, causing serious erosion. To counter this, it was decided to (re)plant spekboom trees. This tree originates from the region, and does not need much water. The idea is that because of the spekboom trees, the soil, and most importantly the groundwater, will be better retained and for longer. That costs a lot of money, however. Initial research was therefore first required to measure the true effect of (re)planting the spekboom trees.

How does Eijkelkamp Soil & Water make the difference?

To measure the effect, Marjan used the Eijkelkamp Soil & Water rainfall simulator. “It is a trough measuring half a square meter that can hold two litres of water. I alternated between placing it on a piece of soil with trees, and one with no trees. The water hit the soil in droplets via the rainfall simulator. I collected the water that was not absorbed into the soil, which allowed me to calculate the amount of water uptake by the soil.”

Marjan is very enthusiastic about the Eijkelkamp Soil & Water rainfall simulator: “The rainfall simulator is a really great tool that makes it relatively easy to show the effect of vegetation on interception and infiltration.”

Results of the research

The research showed that (re)planting spekboom trees does indeed have a substantial effect on water retention. Water retention was up to 80 per cent better than on unplanted soil. The research also helped to make the land-users aware of the problem, precisely because it is a simple and transparent research method.


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