Land Degradation in North Africa

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Land Degradation in North Africa

• Higher Geography

Case Study The Sahel
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Introduction

• When soil is bare, it can easily be blown away by
  the wind or washed away by rain.
• This is called soil erosion.
• If a lot of soil is eroded it becomes less and
  less fertile (degradation ) until the land cannot
  be farmed and it becomes useless, usually as a
  result of human activities. This is called
  desertification.

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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.
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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 high potential erosivity.

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ITCZ

• The rainfall pattern in the Sahel region is a
  result of the Intertropical Convergence Zone
  (ITCZ) which migrates across the region each
  year.
• During the dry season, Tropical Continental air
  is dominant along with dry Harmattan winds
  blowing across the Sahara.

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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
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Traditional way of life

• Most people are herders of sheep, camels or
  goats. They move from area to area to find enough
  water and grazing land.
• They are called nomadic herders.

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Causes of rural land degradation in the Sahel

• 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.

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Physical Factors
Some years are wetter than average and some are
much dryer.
Although the Sahel should get 100-500mm of rain
each year, the rainfall is very unreliable.
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Desertification
Some years are wetter than average and some are
much dryer.
Although the Sahel should get 100-500mm of rain
each year, the rainfall is very unreliable.
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.
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Unpredictable Climate

• Burkina Fasos cotton crop destroyed by flash
  floods in 1994, 1996 1997.
• 67, 000 tonnes of emergency food aid were
  required by Burkina Faso to deal with food
  shortages caused by drought.

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Human Factors

• Improved medical care resulting in a reduced
  death rate, coupled with high birth rates means
  that rapid population growth is occurring in the
  Sahel.
• In countries such as Burkina Faso and Mali
  populations are increasing by at a rate of 2.5
  per year (while at the same time food production
  increases by only 1 year)

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Overcultivation

• Rising populations have also forced farmers to
  increase the amount of land utilised for arable
  farming.
• This has led to the cultivation of marginal areas
  (edge of the Sahara).
• These are not a viable option in terms of
  sustained crop production and as a result
  cultivating them accelerates the process of
  desertification.

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Overgrazing

• 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.
• Compaction of the soil by trampling reduces the
  infiltration capacity of the soil and increases
  run off.

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Deforestation (1)

• Since 1990, 90 of forests have been cleared in
  the Ethiopian Highlands.
• Deforestation removes the binding effect of tree
  roots and prevents the trees from reducing wind
  speed.
• The shortage of fire wood means that more and
  more families are having to resort to animal dung
  and crop residues for their domestic energy
  requirements.

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Deforestation (2)

• The dung and crop residues would normally be used
  as fertiliser so the soil is further degraded as
  it is deprived of essential nutrients.
• In the long term this will affect crop yields.

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Urbanisation

• Urbanisation has led to an increased demand for
  firewood.
• Large areas of forest are cut down and the wood
  is often turned into charcoal for ease of
  transport.
• This process is extremely inefficient and half of
  the energy of the wood is lost during conversion.

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Growth of cash crops

• During the twentieth 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.

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Physical consequences of land degradation

• The increasing frequency of drought periods, the
  farming of marginal areas along the northern
  boundary of the Sahel and deforestation have led
  to the southwards expansion of the Sahara desert.

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Facts
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Physical Consequences

• Rills and gullies
• Loss of topsoil
• Salinisation

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Social and economic consequences of land
degradation

• Malnutrition and starvation The failure of
  crops year after year leads to starvation and
  death eg Sudan and Ethiopia (mid 1980s).
• Cash crop farming can also lead to malnutrition.

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Migration

• Many people have now migrated away from the
  Sahel.
• This has led to the loss of traditional farming
  techniques and in some cases (eg northern Niger)
  a demographically imbalanced rural population.

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Dependence on external support

• Where the effects of land degradation and drought
  have been the most acute, people have come to
  rely on food and other aid sent from other
  countries, eg the band aid campaign of 1983.
• This can lead to over dependency on external help.

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Access to education and healthcare

• In many Saheian countries such as Burkina Faso,
  education and health care must be paid for and
  therefore the loss of income brought about by the
  failure of crops and herds may mean that
  individuals have their schooling interrupted and
  individuals go untreated when ill.

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Solutions to RLD
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Solution 1 Irrigation

• There have been several expensive irrigation
  schemes where rivers have been dammed and
  reservoirs formed.
• The water from the reservoirs is then taken by
  canals to irrigate large areas of farmland.

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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.

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The GeziraScheme
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The Gezira Scheme
Farmer income has increased considerably
Wheat is grown for food
Cotton is grown for export
Farmers can have two harvests a year
Advantages
150 000 people are now employed there.
Crops grow even though there is little rain
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The Gezira Scheme
The reservoir flooded land which had previously
been used by local farmers
Only helped people in one small area of the
country
Disadvantages
Very expensive
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Solution 2 - Terraces

• There are over 200 000 kilometres of terraces in
  Ethiopia.
• They help trap water, stopping it from washing
  the soil away.

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Solution 3 Afforestation

• Planting new trees helps to bind the soil, and
  also provides shade, windbreaks, nutrients and
  fuel for families.
• Depending on the species planted the trees may
  also provide nuts and fruit for humans and
  animals.
• Tree planting needs to be sustainable if it is to
  be successful in the Sahel.

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Solution 4 Stone lines

• In Burkina Faso and other Sahel countries local
  people have built lines of stones along contours
  on their sloping farmland.
• These stone lines trap run-off after heavy rain
  so that the soil is not washed away.
• Crops also grow much better in the deeper soil
  behind the stones.
• This method requires a lot of labour but is cheap
  and simple to work.

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• Organisations such as Oxfam and Tear Fund, have
  used this method very effectively. In some cases
  crop yield has increased by as much as 50.

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Other methods (1)

• Managed grazing areas
• Reduced herd sizes

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Other methods (2)

• Education
• Fuel efficient stoves