Solutions to land degradation – Sahel STARTER – Describe how the turning of land into desert affects the people of the Sahel http://www.canada.com/cms/binary/5314242.jpg Learning Intensions: To describe the solutions to land degradation in the Sahel To discuss how effective these methods have been.

Important! Complete the tasks in your booklet (page 16 – 19), using the information on the following slides. The most successful schemes/ solutions to desertification in the Sahel will be: Low cost Low/ intermediate technology Uses local people. This is because the solutions need to be sustainable in a poor area of the world where there is limited access to technology and education. People need to be able to help themselves if the scheme is to be long lasting and not stop if the funding runs out or the technology breaks.

Agroforestry/ Afforestation Pupil booklet - Page 16 Pupil booklet - Page 16 Agro forestry: combines farming with tree planting therefore allows farmer to continue growing crops. It is effective if deforestation does not exceed afforestation i.e. trees cut down at faster rate than they are being replanted. However the big problem is that trees take time to grow and therefore there is a time gap before benefits are realised. Expensive irrigation and maintenance of trees may be needed. Trees can also use up valuable water and nutrients. https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRu2BA5-7z5jR33dUU4n1McoTJLWnXVRKtgvLKwjndKfWRiTPAFCQ

Pupil booklet - Page 16 In parts of West Africa, the Kad tree (a variety of Acacia tree) is used in an attempt to restore soil fertility. The advantages of this tree are: It retains its leaves in the dry season, providing shade for the soil It fixes nitrogen in the soil, thus, raising fertility Its seeds and pods provide a rich sources of protein for cattle and goats. There are also advantages depending on the trees that are planted. Some provide food for the local people (fruit/ nuts) and the trees can be thinned and the wood used as fuel.

Water Harvesting Pupil booklet - Page 16 This process helps to conserve the small amounts of rain that falls in the Sahel. Tree are planted in small bowls called a microbasin. The water runs off the land into these basins. It is effective because it is cheap and does not rely on complicated technology or knowledge, only need small hand trowels.

Pupil booklet - Page 17 Microdams or diguettes These are small stone walls built along the contours. Watch the video clip showing the building of these microdams and describe the process in you booklet.

Microdams or diguettes – building the microdams Using simple equipment (a tube with water in and measuring sticks) the local people find the contours by finding where the water is level. They then scrape along the ground to mark the contour and collect stones to lay along the line.

Microdams or diguettes Stages in a micro dam scheme: Villagers collect stones and boulders and align them along the contours to create micro dams. Rain soaks in the area between the micro dams instead of running off down slopes. This happens even with a hard crust. As the water is slower the soil soon builds up behind each micro dam. The soil gradually gets deeper and deeper. Dead leaves and seeds are trapped and eventually decay into valuable organic matter that nourishes the soil. The water has time to soak into the ground and the water table begins to build up. Farmers are able to grow crops like millet. The yields are dramatically higher in the fields with micro dams than those without them.

1 – Soil washes down gentle slope by rainwater 2 – Line of stones (Diguettes) across contour line reduces water run-off = less soil erosion. 3 – Water flow very slow because stones have ‘checked’ the flow. 4- Any soil that is washed downslope builds up behind the stone line 5 – Due to slower flow, water infiltrates into and through the soil

Terraces or the Fanya Juu method Pupil booklet - Page 18 & 19 Terraces or the Fanya Juu method On steeper slopes terracing (building steps into the land). This is effective as it prevent run-off by creating flatter land and slowing water down, this reduces erosion and increases the amount of water infiltration. However, this method can be expensive to do and maintain and so the cheaper FANYA JUU method can be used.

Fanya Juu method Ditches are dug and the soil piled up behind, as water moves down the slope it is stopped by the mounds of earth and the soil it is carrying piles up behind. Over time the soil build up and the land flattens out. The water also has time to soak into the ground and build up the water table.

Homework Referring to named locations in a developing country you have studied: Describe and explain the ways in which farmers have adjusted their farming methods to reduce the risk of soil erosion; and Comment on the effectiveness of these methods. 10 marks