Cause 1: Climate Change


The Sahel region is an arid/semi-arid region, meaning it receives low annual amounts of rainfall. It has a wet season from May to October, with rainfall occurring in heavy downpours. The high temperatures of the region evaporate the rainfall quickly. During a 30-year spell between 1930 and 1960, the Sahel experienced higher levels of rainfall, which encouraged inward migration to the region. However, since this time rainfall has become less reliable, with the wet season shortening by 29 per cent over the past 30 years. A delay in the arrival of rain and a shorter wet season has triggered several devastating famines as the region’s population are unable to grow enough food for themselves. Examples include: l


10 20 30 40


0


–10 –20 –30 –40


: Fig. 2.7 Rainfall levels have been reducing in the Sahel.


GEO DICTIONARY


1968–72: Drought (Mauritania, Mali, Chad, Niger, Burkina Faso) – 1 million dead


l


1998: Sudan – Famine caused by a combination of war and drought – 70,000 dead


l


2012: Famine in West Africa brought on by Sahel drought – 18 million dead


l


2016: An estimated 14.28 million people remain living with no food security, with an additional 2.6 million living with an immediate risk of starvation.


When the seasonal rains do arrive, they occur in short torrential downpours rather than longer spells of less intense rainfall. The torrential rain damages the soil’s structure, causing erosion and gullying to occur. Gullying occurs as the rainwater carves out channels in the soil. As well as removing soil, gullying makes the remaining topsoil more susceptible to wind erosion as its structure is damaged. The intense heat of the region means the rainfall is evaporated quickly and is not allowed to percolate through the soil. This means that the water table is not replenished, and becomes increasingly dry. The high temperatures cause high levels of evaporation. This, combined with disruption to rainfall patterns through climate change, has led to wells drying up and prolonged periods of drought. Eventually the soil becomes hard and baked into an impermeable laterite soil. The topsoil is removed by the wind.


) Fig. 2.8 Laterite soil of the Sahel


OVERPOPULATION AND DEVELOPMENT 43


Gullying: channels cut into the soil by rainwater


Percolate: the filtering of water down through the soil


Water table: the level below the surface in which the soil is saturated with water


Drought: a prolonged period without rainfall


Impermeable: water cannot pass through it


Laterite: a hard, impermeable clay soil found in tropical or subtropical areas


Biome: unique natural world regions, which are controlled by climate


Elective 5: Human CHAPTER 2


% Variation vs mean


1900 1905 1910 1915 1920 1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010


A


Z


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