Drought and Desertification, with Specific Reference to The Sahel Zone, Africa

Drought is a prolonged period of abnormally low rainfall, leading to a shortage of water, this can some times lead to desertification, which is the process by which fertile land becomes desert, this can also be caused by deforestation or inappropriate agriculture as well. The worst affected area of both drought and desertification is Africa, particularly the Sahel Zone.

Physical Causes

The most important physical cause of drought is the lack of water vapour in the atmosphere because this leads to precipitation such as rain, hail, snow and sleet. Lack of moisture occurs when there are high-pressure air systems, as they cannot hold as much moisture. Change in wind direction is also a factor that can cause drought because warm, dry continental air is blown over an area instead of cool, moist oceanic air. This process can also make dry areas wet.

Human Causes

Deforestation in order to create buildings or for fuel is a human cause of drought and can cause desertification. When buildings are created in areas that used to be forests, drought can occur because there is less soil to absorb moisture and the soil that is there is less able to hold the water, which causes it to dry out, and desertification to occur.

The building of a dam on a large river in order to create HEP electricity and provide water for agricultural land can cause droughts because there is less water available down stream which dries out the land.

The Sahel, North Africa

The Sahel is a large area (500km) in Africa, stretching between Senegal and Ethiopia. It is beneath the Sahara desert, which is very dry, and above the more humid equatorial regions. The land here is semi-aired, which means that it is very close to desert conditions. They also have intense periods of rainfall and then drought, causing desertification.

Causes

The more recent desertification in the Sahel (from the 1960’s) is a result of a many human factors as well as some physical factors. An increase in population in the area, due to children being an economical asset in the agricultural environment, has lead to a number of problems; Deforestation in order to have firewood means that the roots from the trees are not holding the soil together and the leaves from the trees are not protection the soil from intense rainfall. This causes soil erosion, which leads to decertification.

Another reason high population has caused desertification in the Sahel is overgrazing due to the increased amounts of cattle. The cattle graze on the land more, which means there is little vegetation to protect the soils, which causes soil erosion, which equals desertification.

Over farming in the Sahel area because farmers are force to use the same land over and over again means the land has no time to recover and lacks nutrients, this causes it to dry out.

The natural causes of desertification include global warming, which means there are higher temperatures and less rainfall so the ground is dryer and little vegetation can grow.

Effects

The effects of drought and desertification in the Sahel are both natural and human. The effects include soil erosion so no vegetation can be grown in it. This affects the livelihood of farmers who rely on the land to make money and feed their families. This also affects wild animals such as wildebeest’s, which have little food to eat therefor die. This is known as reduced biodiversity.

Desertification also causes flash floods due to more surface run-off; this causes the makeshift homes of the local people to be washed away ruining lives.

Dry rivers are an effect of desertification and drought. This means there is even less water available for local people which leads to sickness amongst humans and livestock, and failure of crops as there is no water to water them. People lose their livelihoods and possibly loved one lives due to this shortage of water.

Due to all of these local effects people may migrate to cities, which increases the inhabitants of shantytowns in already overpopulated areas. Some people are even forced to leave their country due to the drought and become refugees in other countries.

Solutions

Planting trees in these areas will mean that roots can hold the soil together, preventing soil erosion and the leaves on the trees can protect the ground from weathering. This is cheap and long term and will provide fuel for fires or material for buildings in the future, so is therefor sustainable.

Terracing the soil prevents the wind eroding the soil, which is a cheap way to prevent desertification, which only requires manpower but is not long term. A similar method to terracing is known as magic stones, which are placed along contours preventing soil being eroded away, this has the same advantages as terracing.

Charities such as Oxfam are also doing all they can to hep the Sahel by building wells so locals can collect water for their families and for their farms. Oxfam are also building irrigation systems to channel water from areas of surplus to areas of deficit.
Bibliography

http://geography.about.com/od/globalproblemsandissues/a/drought.htm http://www.bbc.co.uk/schools/gcsebitesize/geography/water_rivers/drought_rev1.shtml http://oceanworld.tamu.edu/resources/oceanography-book/desertificationinsahel.html
http://www.slideshare.net/sarahmarks/sahelcasestudy