Sahel - water and extreme climate

Question 1

Where is the Sahel situated?

Answer 1

Location
• Lies on the southern edge of the Sahara desert
• Transition zone between the arid Sahara and wetter grasslands of southern Africa
• 3000km east to west
• 900km north to south
• Semi-arid region

Question 2

Why is it so crucial that there is rain in the Sahel?

Answer 2

• Many people in the region are subsistence farmers and nomadic herders
• Nomads graze animals and subsistence farmers rely on rain to grow millet and maize
• Countries in the Sahel such as Chad and Niger are some of the poorest developing countries in the world so can’t afford to have water insecurity

Question 3

What water problems exist in the Sahel?

Answer 3

• The countries of the Sahel region are suffering from severe water stress and chronic water shortages
• Rain falls in only 1 or 2 months of the year (250mm-450mm per year, UK’s average is 887mm per year)
• Length of the rainy season is variable (farmers are dependent on rainy season)
• Overgrazing of the land by animals has led to soil erosion
• Water demands are increasing as the population of the Sahel increases as countries in the Sahel develop

Question 4

What are the geographical impacts of climate change and changing precipitation levels in the Sahel?

Answer 4

• The Sahel naturally receives less rainfall due to its geographical positioning in the middle of a Hadley cell
• Precipitation in the Sahel is predicted to become more variable and is expected to decline due to climate change
• Sometimes rainfall falls as a monsoon leading to flooding
• Lower levels of precipitation and eroded land leads to desertification
• Droughts also cause seasonal rivers, water holes to dry up and the water table to fall

Question 5

What are the social and economical impacts of climate change and the change precipitation levels in the Sahel?

Answer 5

• As rainfall decreases and becomes more unreliable more people are forced to migrate to the cities
• Desertification can lead to droughts which can cause famine and will reduce food supply as harvests fail
• During dry spells, soil blows away creating dust storms which can reduce crop yields

Question 6

Precipitation levels fact

Answer 6

Rainfall is expected to decrease by roughly 10% by 2030

Question 7

What are the solutions to water insecurity in the Sahel?

Answer 7

Diguettes

Boreholes

Question 8

What are boreholes?

Answer 8

Wells that have been dug in the ground in order to acquire groundwater for irrigating crops

Question 9

What is the major problem with boreholes?

Answer 9

However this water evaporates quickly in the arid conditions leaving salt on the soil (salinisation) which poisons the soil (decreases crop yields)

Question 10

What are diguettes?

Answer 10

A diguette is a line of stones laid along the contours of gently sloping farmland that slows down rainwater and gives the water a chance to soak into the ground.
The diguettes also trap sediment, causing soil to build up behind the stones.

Question 11

Facts about diguettes?

Answer 11

Type of intermediate technology that is built using local materials and labour, cheap and sustainable solution
Impact: Soil erosion was reduced and crop yields
Over 400 villages in Burkina Faso now have diguettes
A study found that soil depth without diguettes decreases by 15cm; with diguettes soil depth increased by 18cm
Implemented by oxfam in 1979

Question 12

What is intermediate technology?

Answer 12

Technology that is sustainable because it is suited to local resources and knowledge

Question 13

What is desertification?

Answer 13

The gradual change of land into desert

Question 14

What is water stress?

Answer 14

When the demand for water exceeds the available amount during a certain period or when poor quality restricts its use

Question 15

Who are Nomads?

Answer 15

People who move with their animals from place to place in search of pasture

Question 16

What determines whether a place is semi-arid?

Answer 16

A place which has less than 500mm of precipitation per year