Higher Geography Human Environments

Transcription

1 Duncanrig Secondary School Higher Geography Human Environments Rural Geography 1

2 Rural Land Degradation in the Developing World Case Study: The Sahel The Sahel is a region of semiarid grassland and desert along the edge of the Sahara Desert. The area covers about 1.1 million square miles (3 million square km) and includes Mali, Mauritania, Niger, Senegal, Sudan, Burkina Faso, Chad, the Gambia and Guinea-Bissau. It is one of the poorest regions in the world and has suffered several severe droughts and subsequent famine. Desertification is also a major problem in the region, in certain localities within the Sahel, the Sahara desert is advancing southwards at an average rate of 5-10km per year. Desertification Desertification is the process by which fertile land becomes desert. Climate change is an influence in desertification, but the main factors of why desertification rates are so high are human: Over-grazing of livestock Over-cultivation Deforestation Salination of the soil These processes all weaken the composition of the soil, leading to it being easily eroded by the wind and water. The fertile topsoil is eroded, leaving less fertile soil behind, so people search for another area for agriculture, expanding the damaged area. Irrigation allows water to become close enough to the surface so it evaporates; this leaves behind a layer of salt, making the soil infertile. 2

3 Land in these areas, if not managed properly, can become barren quickly. It is one of the main environmental problems facing hot desert environments. Deserts are fragile ecosystems that cannot cope with a sudden change. If humans do disturb the area if can lead to a reduction in biodiversity and the soils can lose much of their productivity, eventually being unable to support any vegetation. Causes of Desertification Deforestation Rural-urban migration has led to a growing demand for wood for fuel and land to grow crops. Trees are already scarce in the area and further deforestation reduces interception and water storage leaving the soil dry and vulnerable to wind and water erosion. Removing trees removes root systems which would hold soil together, and destroys shelter belts which would have protected soil from wind erosion. Population increase Desertification has caused people to migrate southwards within the Sahel leading to increasing population and increased pressure on already fragile land. Also many nomads have been forced to settle in villages, leading to greater food requirements and overuse of marginal land e.g. Burkina Faso. In some places peasant farmers have had to farm marginal land due to the best land being used for cash crops (eg in parts of Sudan). Overgrazing Allowing more grazing than the pasture can support. This increases where herd size is a status symbol. Overgrazing exposes soil to winds by loss of vegetation cover, hooves break up soil making it susceptible to wind and water erosion, and in some cases compact the soil, especially near water holes. 3

4 Overcropping This means soil structure breaks up, with monoculture depleting nutrients, reduced fallow times meaning soil cannot rest or recover, marginal land eg slopes being used and becoming susceptible to wind and water erosion. Inappropriate farming techniques Including monoculture, inappropriate ploughing eg deep ploughing of fragile soils, irrigation leading to salination, lack of organic fertilisers used. Impacts of Desertification Impact on People and the Economy Crop failures and death of livestock, reducing food supply, leading to malnutrition and famine Increased infant mortality rates / death rates e.g. Ethiopia, Sudan Country Infant Mortality Rate Death Rate Life Expectancy at Birth UK Mali Niger Chad Sudan Ethiopia

5 Collapse of the traditional nomadic way of life Large scale rural migration into overcrowded urban areas, causing more pressure and the growth of shanty towns Tuareg Factfile The Tuareg are a nomadic people who move with their livestock across the Sahel. They have faced many challenges in recent years due to both physical and human factors. The geographical area in which they travel has been significantly reduced due to conflict within countries e.g. Mali, severe drought (linked to climate change) and the Southern encroachment of the Sahara Desert. As life has become more difficult, many Tuareg have been forced to move into villages and towns resulting in a loss of traditional skills and techniques. Conflict within and sometimes, between countries as people move and re-settle growth of large refugee camps 5

6 The breakdown of the settled farmer/nomad relationship in places like Yatenga province in Northern Burkina Faso Countries increasingly reliant on international aid Disease and illness can become endemic. Impact on the Environment Soil structure deteriorates due to over-cropping and over-grazing Wind erosion can remove large amounts of dried out soil Advance of the Sahara desert Water tables lowered Torrential rains can lead to gully erosion Intensified drought due to the albedo effect Trampling by animals also compacts the surface and leads to reduced infiltration, which causes increased overland flow and erosion. 6

7 Solutions to Desertification in the Sahel Animal fences Movable fencing allows farmers to restrict grazing animals to specific areas of land and allows remaining land to recover. This allows farmers to move animals between fenced areas, reducing the dangers of overgrazing and trampling of soil and allowing the soil and land to recover between grazing sessions. Fencing can also provide a shelter belt that protects topsoil from wind erosion. Magic Stones or diguettes This is a simple but very effective method of conserving soil. Diguettes are lines of stones laid along contours of gently sloping farmland to catch rain water and reduce soil erosion. Diguettes allow the water to seep into the soil rather than run off the land. This prevents soil being washed away and can double the yield of crops such as groundnuts. Afforestation This helps to increase interception and reduce surface run off. Trees also reduce wind erosion by decreasing wind speed. The trees also help to bind the soil and especially good for steep slopes, this is an effective method due to creating coverage but does reduce the amount of land available for farming e.g. tree planting schemes in Mauritania Afforestation Case Study: The Great Green Wall Initiative The Great Green Wall project is backed by the African Union and is aimed at halting the advancing Sahara Desert. The belt would be 15km (nine miles) wide and 7,775km (4,831 miles) long. The initiative, conceived in 2005, has not started because of a lack of funding and some experts worry it would not be maintained properly. It is envisaged that the belt would go through 11 countries from east to west. The trees should be "droughtadapted species", preferably native to the areas planted, the Great Green Wall website says, listing 37 suitable species. The initiative says it hopes the trees will slow soil erosion; slow wind speeds and help rain water filter into the ground, to stop the desert from growing. It also says a richer soil content will help communities across the Sahel who depend on land for grazing and agriculture. Senegal says it has spent about $2m ( 1.35m) on it and communities are being encouraged to plant trees. 7

8 Sustainable Agriculture a) Agroforestry Agroforestry is a practice which integrates multi-purpose trees and shrubs into farming systems Agroforestry systems include alley cropping, windbreaks, riparian buffer strips, and forest farming The trees shelter land and livestock, provide wildlife habitat and control soil erosion Leguminous species (plants that extract nitrogen from the air and fix it in the soil) improve soil fertility, fruit trees provide nutrition Trees like the Acacia Senegal, provide gum and medicine Alley cropping is a simple technique that restores nitrogen to the top layer of soil so that farmers can use the same piece of land year after year to grow their crops. Nitrogen-fixing trees are planted between rows of such staple crops as corn and cassava. Acacia Senegal Riparian Buffer b) Bunding, contour bunding and terracing These are techniques for halting erosion With bunding grids of earth mounds enclose areas of land, preventing runoff and allowing rainwater to percolate down to replenish the water table and preserving what is left of the topsoil Physical structures, such as bunds, should be complemented by other approaches such as the use of manure and rotation with leguminous crops to enhance the fertility of the soil 8

9 Bunding Terracing c) New improved crops: New varieties and strains of crop, which are the result of biotechnological research, are capable of growing in areas of deficient rainfall. High yielding and drought-resistant varieties will reduce starvation Use drought-resistant seed such as millet (northern Nigeria) Using alternative sources of energy Fast-growing, drought-and salt-tolerant, prosopsis is a natural fuelwood in arid and semi-arid areas. The wood has been called wooden anthracite, because of its high heat content. Prosopsis spreads along the ground and helps to reestablish the soil, protecting it both from strong winds in the dry season and from strong sunlight. The pressure on natural vegetation cover can be reduced through the development of alternative sources of energy and through improving the efficiency of existing energy use. Improved ovens with slow-burning wood are one way to save energy In Eritrea, Concern promoted the use of fuel saving stoves, known as mogogos. Mogogo 9

10 Better management: Non-governmental Organisations Associated with the United Nations (NGO) have been successful in local desertification projects. These projects are supported by the United Nations Environment Programme (UNEP) o For example Oxfam, Concern, Eden Foundation NGO Case Study: The Eden Foundation Niger is one of the driest countries in the world, situated south of the Sahara desert. The people are poor and have neither money nor water to spare. Eden s solution is to bring trees and bushes that can grow naturally in this dry area and give food, even in times of need. Since their arrival in 1987, Eden has helped more than 2600 households in the region. The trees and bushes they offer have been researched and need neither irrigation nor chemical fertilisers to grow. 10