2. www.sahsgeo.wikispaces.com CASE STUDY SEMI ARID AREA THE SAHEL, AFRICA

3. DEVELOPING WORLD CASE STUDY

4. SOME KEY TERMS AND DEFINITIONS. Drought - an extended period of drier weather than is usual (in the Sahel this can last for more than 10 years). Desert - A dry area, hot or cold, where total annual precipitation is less than 250 mm. Usually treeless Desertification - the destruction of soils and vegetation in arid (dry) regions. Semi-Arid Area -Rainfall patterns are erratic, a high rate of evapotranspiration. Precipitation between 250-600mm. Support small shrubs.

5. CASE STUDY: THE SAHEL, AFRICA

6. LOCATION The Sahel runs parallel to the southern edge of the Sahara Desert from the west coast to the east coast of Africa. The average width of the Sahel is 500km. Its proximity to the Sahara is one of the principal reasons it is prone to desertification.

7. CLIMATE Total annual rainfall is low, ranging between 200mm in the northern Sahel to 500 mm in southern Sahel. Rainfall is unreliable and highly variable. Rainfall occurs in a very intense tropical downpour, creating erosion in the soils. Rains fall (infrequently) as heavy showers so the rainfall is usually lost to run off

8. NATURAL ENVIRONMENT Range of species and vegetation decreases Soil depth decreases and soil erodibility increases Total rainfall decreases and rainfall reliability decreases Soil moisture decreases due to increase in sand content OUR CASE STUDY AREA

10. The UN Environmental Programme (UNEP) estimates that 35% of all land is at risk from degradation.

11. More than 75 billion tonnes of soil are washed into the sea or swept away by the wind each year and can never be replaced.

12. 6 million tonnes of land is lost to desert each year.

13. 100 countries, 1 in 5 of the world’s population, are affected by land degradation.

14. CAUSES OF RLD The causes of rural land degradation in the Sahel cannot be attributed to any one factor, but an interaction of a wide range of both physical and human variables. Physical factors – droughts, unpredictability of climate, flash floods. Human factors – population growth, overcultivation, overgrazing, deforestation, urbanisation, growth of cash crops

15. Degradation involved the removal of vegetation cover from an area. Vegetation is important because roots help to bind the soil together, it help to intercept precipitation, and it can protect the soil from the effects of wind. WHAT IS DEGRADATION? HOW DOES IT HAPPEN? 1.WATER RAINSPLASH – raindrops hitting the ground can dislodge soil SHEET EROSION - the topsoil is removed by heavy rain flowing down a slope. RILL EROSION – heavy rain create small river channels which can lead to gullies. LEACHING - heavy rain washes minerals from the topsoil.

16. SALTATION Soil particles close to the ground move in a series of bumps, bounces & rolls (tumbleweed) SURFACE CREEP A slow movement over ground, usually large soil particles and rocks. HOW DOES IT HAPPEN? 2.WIND SUSPENSION – A DUST STORM fine soil is blown by the wind and is suspended in the air.

17. PHYSICAL AND HUMAN FACTORS OF RLD

18. population growth, overcultivation, overgrazing, deforestation, urbanisation, growth of cash crops Mono-cultivation HUMAN FACTORS droughts, unpredictability of climate flash floods. PHYSICAL FACTORS Note the definitions for each term….

19. DESERTIFICATION Physical Although the Sahel should get 100- 500mm of rain each year, the rainfall is very unreliable. Some years are wetter than average and some are much dryer. With very little rain, few crops can grow so there were few roots to hold the soil together. At the same time, the soil dries out and is easily blown or washed away. The soil is eroded until some of the land is turned to desert. http://www.bbc.co.uk/learningzon e/clips/desertification-and- climate-change/1501.html

20. 1. CLIMATIC VARIABILITY AND CHANGE 2. DEFORESTATION 3. OVERGRAZING 4. OVER CULTIVATION FOUR MAIN CAUSES OF DESERTIFICATION WE WILL LOOK AT THESE LATER ON IN THE PPT

21. Consequences Environmental As vegetation is removed the roots are no longer able to bind the soil together and the soil becomes vulnerable to wind erosion. The fertile topsoil is easily blown away. The land becomes infertile, turning to desert, eg the expansion of the Sahara desert. Social People are forced to migrate, with many people - young men in particular, leaving to work in cities and towns. This puts pressure on already limited urban resources. Disputes occur over land between herdsmen and farmers. Food shortages lead to malnutrition and famine, eg in Ethiopia. This also results in increased movement to refugee camps. Economic As the land becomes unproductive, farm income falls. This leads to widespread poverty and an increased reliance on overseas aid.

22. http://www.bbc.co.uk/education/guides/z9rbb9q/revision/4 The video below looks at Burkino Faso and the local impact of desertification VIDEO LINK

23. For a named area you have studied, discuss the consequences of RLD on the people and the environment OR Referring to named locations in either a semi-arid area or a rainforest area in a developing country, discuss the consequences of RLD on the people and the environment (6 marks each) EXAM STYLE QUESTION 1

24. Approx. 20 million people suffer from food shortage in the Sahel. One of the consequences of land degradation in the Sahel is crop failure which in turn leads to people being under nourished and deaths from starvation. These famine conditions have affected countries such as …………….. along the Sahel. When people are under nourished they are then susceptible to diseases such a kwashiorkor. IMPACT ON PEOPLE

26. Disease and illness becomes widespread so people are then unable to work and will therefore have no money to buy food. As people become weaker the cycle of poverty develops. People living in rural areas in the Sahel are then forced to leave the countryside and move into the cities in search of food and employment (THINK POPULATION – FORCED MIGRATION) Many of these people cannot find anywhere to live or employment and end up living in a shanty town on the edge of a city (THINK URBAN UNIT) Migrants tend to be young males, creating additional problems in shanty towns. E.g becoming involved in gangs and crime

27. As a result of this a major impact on people is that the traditional way of life for nomads is under threat which leads to people dying, communities broken up and a way of life lost. Government and charity organisations may have to set up refugee camps in areas however conditions are likely to be appalling with overcrowding and insufficient health and education facilities. Population pressure – with an increasing population, they carrying capacity of an area can be exceeded. I.e the maximum number of people who can be supported by the resources of the environment where they live.

28. IMPACT ON ENVIRONMENT GROWTH OF CASH CROPS During the 20th century some farmers in the Sahel moved away from traditional techniques and began growing cash crops such as cotton and rice. This monoculture often combined with inappropriate farming techniques has rendered the soil infertile in many areas. Also monoculture farming (growing the same crop for many years) destroys the soil.

29. OVERCULTIVATION This is where pressure is put on the land. If too much is taken from the soil without replacing the nutrients the land will not be suitable for growing crops and puts too much pressure on the soil. Farmers should allow the land to be fallow and not be over ambitious during “wet” season. IMPACT ON ENVIRONMENT

30. OVERGRAZING – Simply animals eating too much! Places pressure on certain grazing areas particularly around wells, lakes and rivers. The concentration of herds in these areas results in vegetation being stripped down to its roots, leaving soil exposed. This has happened in the Sahel as there is a tendency to equate wealth with the number of cows you own. In Mali, the number of cattle, sheep and goats increased by 40% between 1995 and 2005 AFTERBEFORE Best chat up line ever!

31. BEFORE AFTER

32. IMPACT ON PEOPLE AND ENVIRONMENT Malnutrition and Starvation (P) Migration (P) Dependence on external support – Government and Charity (P) Loss of access to education, work, money. (P) Loss of income for farmers – Cycle of disease. (P) Overcultivation (E) Overgrazing (E) Heavy infrequent rainfall washing away soils turning a semi arid area into a desert. (E) RECAP

33. SOCIAL crop failures and the resulting malnutrition leading to famine eg Sudan, Ethiopia and much of the Sahel  migration on a large scale − usually into shanties on the edge of the major cities  the collapse of the nomadic way of life due to the lack of grazing and water  many nomads forced to settle in villages − with a consequent increase in pressure on the surrounding land

34.  the breakdown of the settled farmer/nomad relationship in places like Yatenga province in Northern Burkina Faso  reliance on aid and living in refugee camps  exploitation by armed groups in civil wars eg Sudan  loss of education --- this must be paid for so loss of income means loss ofeducation to children and locals.

35. Environmental;  The loss of soil by gullying – the land is dry so the dusty upper surface is easy to wash away in the torrential seasonal storms.  Trampling by animals also compacts the surface and leads to reduced infiltration, which causes increased overland flow and erosion.  Strong seasonal winds blow away dry soils.  Salinisation occurs where evaporation rates at the surface are very high, on land that has been flood irrigated. This draws minerals to the surface in solution and as the water evaporates the salts are left behind.

36. For a named area you have studied, explain the techniques used to combat RLD in a named rainforest or semi arid area you have studied. (6 marks) EXAM STYLE QUESTION 2

37. 1. MOVEABLE FENCING This allows farmers to restrict grazing animals to specific areas of land and allow remaining land to recover. This reduces overgrazing and trampling of soil. 2. COUNTOUR PLOUGHING This can be used to prevent soil being washed downhill. Contour ploughing is the practice of ploughing across a slope following its contour lines. This slows down water run off during heavy rainfall preventing soil erosion. MANAGEMENT STRATEGIES

38. 3. SHELTER BELTS Trees are planted in rows and act as a shelter to stop the wind drying out the ground and blowing the soil away. Also roots bind the soil. Trees can be grown for shade to allow crops to be grown in between rows. 4. IRRIGATION – GEZIRA SCHEME – SEE NEXT SLIDE In drier areas of the Sahel, Irrigation is now used as it keeps the soils moist, allows crops to grow and prevents soil being blown away. 5. STONE BUNDS Barrier that slows down water run off and allows rainwater to seep into the soil and spread more evenly over the land. This also keeps the soil rich in nutrients.

39. 6. EDUCATION Government and charity organisations are educating the Nomadic people of the Sahel on how to cultivate the land and get the most out of the land. 7 TERRACING This is a type of farming completed on steep slopes. They are an effective type of farming in the long run, however they take time to construct and require regular maintenance. FOUND IN THE SAHEL – PUT THIS IN YOUR ANSWER

40. THE GEZIRA SCHEME In Sudan the Gezira scheme allows one million hectares of land to be irrigated using water from the White Nile and Blue Nile.

41. THE GEZIRA SCHEME

42. Advantages Crops grow even though there is little rain Farmers can have two harvests a year Farmer income has increased considerably Cotton is grown for export Wheat is grown for food 150 000 people are now employed there.

43. THE GEZIRA SCHEME Disadvantages Very expensive The reservoir flooded land which had previously been used by local farmers Only helped people in one small area of the country