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Wageningen Universiteit (2006)

Wind erosion control with scattered vegetation in the Sahelian zone of Burkina Faso

Leenders, J.K.

Titre : Wind erosion control with scattered vegetation in the Sahelian zone of Burkina Faso

Auteur : Leenders, J.K.

Université de soutenance : Wageningen Universiteit

Grade : PhD thesis 2006

Résumé
The Sahelian zone ofAfricais the region that is globally most subjected to land degradation, with wind erosion being the most important soil degradation process. By using control measures, the negative effects of wind erosion can be reduced. At present, adoption of wind erosion control measures by Sahelian farmers is low, as most recommended measures do not fit into the farming systems. Therefore, the possibilities of using the local agro-forestry system, i.e. scattered vegetation of trees and shrubs as a wind erosion control strategy were explored in this study. The study area was located in the Sahelian zone of Burkina Faso. A survey among farmers revealed that they generally have a good knowledge of wind erosion processes and the possible wind erosion protection by natural vegetation. Detailed field measurements of wind speed and sediment transport revealed that the fluctuations in horizontal wind speed mainly cause wind erosion. Measurements around isolated vegetation elements revealed that these elements reduce wind speeds and sediment transport, and they are effective in trapping material already in transport. The effectiveness in reducing wind speed and sediment transport of scattered vegetation depends on the number of vegetation elements, the type of vegetation element and the height, width and porosity of the canopy of the element. A model was developed to simulate field-scale wind erosion with different types and arrangements of vegetation elements. This model can be used to develop optimal vegetation cover densities and spatial arrangements for wind erosion control. Overall it can be concluded that the use of the local agro-forestry system as a wind erosion control strategy is promising.

Mots clés : wind erosion / erosion control / arable land / vegetation / wind speed / soil degradation / simulation models / sahel / burkina faso

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