University of Bonn

Soil erosion modelling at hillslope scale in Burkina Faso

Terrain analysis at hillslope in Dano, south-western Burkina Faso
Soil erosion is a major factor for land degradation in the semi-arid environment of Burkina Faso.
The loss of nutrient-rich topsoil from hillslopes causes severe agricultural problems and can lead to diminished soil fertility and reduced crop yield, which is particularly serious in countries dependent on soil as an agricultural base for their food production.
Therefore, it is necessary to quantify soil loss and to identify adequate land management strategies to prevent topsoil from being eroded.

The physically-based Water Erosion Prediction Project (WEPP) - model was applied to simulate soil loss and runoff at hillslope scale in South-Western Burkina Faso.
Additionally, an environmental tracer method (137Cs) was used to identify most erosion-affected hillslope zones.

The 137Cs technique is a more recent, promising method to quantify mid-term soil erosion and deposition rates by measuring the remaining concentration of 137Cs in the soil.

Spatial pattern of soil erosion and deposition at a hillslope in Dano, south-western Burkina Faso, based on a 137Cs conversion model. (Click to enlarge)

Soil redistribution rates calculated by a 137Cs conversion model (Graph) show maximum erosion rates of 37 t ha-1 yr-1 at the summit and shoulder position of the hillslope and maximum deposition rates of 29 t ha-1 yr-1 at the footslope/valley position of the hillslope.

These results correspond well with catenary soil development and show a good agreement with average soil erosion rates of 35 t ha-1 yr-1 predicted by the WEPP-model.

When simulating the effect of land management practices as prevention strategies, results indicate that mulching/residue addition and minimum tillage can reduce average soil loss by 20 % and 30 %, whereas the construction of stone rows can reduce soil loss by up to 90 %.

Considering the high erosion risk and the low nutrient status of the soils, conservation techniques should have both a physical-mechanical function to control runoff and soil loss and a biological-agronomical impact to restore soil nutrients and to improve soil fertility.
A combination of both measures would be the most appropriate option to meet the concept of sustainable land management.


Person in charge: Almut Brunner