HUMAN GEOGRAPHY


Stone lines Burkina Faso is a country that lies within the Sahel. It experiences very infrequent but heavy bouts of rain that can result in sheet and gully erosion even on gently sloping land. Farmers in Burkina Faso place little walls or ‘lines’ of stones (or sometimes of hardened earth) across slopes. The stone lines trap rainwater behind them, so that the water gets time to soak into the ground rather than flow downslope. This prevents sheet and gully erosion and also helps to replenish local water tables. Stone lines are most effective on very gentle slopes where they may take up less than


two per cent of the land but can result in a 50 per cent increase in crop yields. They have the advantage of being cheap and easy to build. In Burkina Faso they are built and repaired during the dry season when other farming tasks require less labour.


Low stone walls are built across a gentle slope


Water trapped behind the stone lines can infiltrate into the ground


Building ‘stone’ lines in Burkina, Faso


Windbreaks Windbreaks or shelter belts are an effective means of conservation in flat areas that are liable to suffer from wind erosion. They are barriers of trees and leafy shrubs that are planted along the edges of fields. They prevent the wind blowing the soil away or flattening or damaging cereal crops such as rice or wheat. Windbreaks can protect large areas of land. Studies in West Africa have shown that their presence can increase crop yields by up to 20 per cent. Many conservation projects in the Sahel include planting windbreaks of native varieties of trees and plants that are suited to local climatic conditions. Windbreaks can also provide a variety of other benefits.


l The roots of windbreak vegetation help to bind soil together and so contribute to soil conservation.


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l Fruit- or nut-bearing windbreak trees are sources of food. l As windbreak trees multiply, they can be thinned occasionally and used to provide firewood or fencing posts.


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