Land Degradation in Land Degradation in North AfricaNorth Africa

Higher GeographyHigher Geography

Case Study:The Sahel

IntroductionIntroduction When soil is bare, it can easily be blown When soil is bare, it can easily be blown

away by the wind or washed away by rain.away by the wind or washed away by rain. This is called This is called soil erosionsoil erosion..

If a lot of soil is eroded it becomes less If a lot of soil is eroded it becomes less and less fertile (and less fertile (degradation degradation )) until the until the land cannot be farmed and it becomes land cannot be farmed and it becomes useless, usually as a result of human useless, usually as a result of human activities. This is called activities. This is called desertificationdesertification..

LocationLocation

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.

ClimateClimate Total annual rainfall is Total annual rainfall is

low, ranging between low, ranging between 200mm in the northern 200mm in the northern Sahel to 500 mm in Sahel to 500 mm in southern Sahel.southern Sahel.

Rainfall is unreliable and Rainfall is unreliable and highly variable.highly variable.

Rainfall occurs in a very Rainfall occurs in a very intense tropical intense tropical downpour, creating high downpour, creating high potential potential erosivityerosivity. .

ITCZITCZ

The rainfall pattern in the Sahel The rainfall pattern in the Sahel region is a result of the region is a result of the Intertropical Convergence Zone Intertropical Convergence Zone (ITCZ)(ITCZ) which migrates across the which migrates across the region each year.region each year.

During the dry season, During the dry season, Tropical Tropical Continental airContinental air is dominant along is dominant along with dry with dry Harmattan windsHarmattan winds blowing blowing across the Sahara.across the Sahara.

Natural EnvironmentNatural 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

Traditional way of lifeTraditional way of life

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

They are called They are called nomadic herdersnomadic herders..

Causes of rural land Causes of rural land degradation in the Saheldegradation in the Sahel

The causes of rural land degradation The causes of rural land degradation in the Sahel cannot be attributed to in the Sahel cannot be attributed to any one factor, but an interaction of any one factor, but an interaction of a wide range of both a wide range of both physicalphysical and and human human variables.variables.

Physical FactorsPhysical Factors

Physical

Although the Sahel should get 100-

500mm of rain each year, the rainfall is

very unreliable.

Some years are wetter than

average and some are much dryer.

DesertificationDesertification

Physical

Although the Sahel should get 100-

500mm of rain each year, the rainfall is

very unreliable.

Some years are wetter than

average and some are much dryer.

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.

Unpredictable ClimateUnpredictable Climate

Burkina Faso’s cotton crop destroyed Burkina Faso’s cotton crop destroyed by flash floods in 1994, 1996 & 1997. by flash floods in 1994, 1996 & 1997.

67, 000 tonnes of emergency food 67, 000 tonnes of emergency food aid were required by Burkina Faso to aid were required by Burkina Faso to deal with food shortages caused by deal with food shortages caused by drought.drought.

Human FactorsHuman Factors

Improved medical care resulting in a Improved medical care resulting in a reduced death rate, coupled with high reduced death rate, coupled with high birth rates means that rapid birth rates means that rapid population population growthgrowth is occurring in the Sahel. is occurring in the Sahel.

In countries such as Burkina Faso and Mali In countries such as Burkina Faso and Mali populations are increasing by at a rate of populations are increasing by at a rate of 2.5% per year (while at the same time 2.5% per year (while at the same time food production increases by only 1% food production increases by only 1% year)year)

OvercultivationOvercultivation Rising populations have also forced Rising populations have also forced

farmers to increase the amount of land farmers to increase the amount of land utilised for arable farming.utilised for arable farming.

This has led to the cultivation of marginal This has led to the cultivation of marginal areas (edge of the Sahara).areas (edge of the Sahara).

These are not a viable option in terms of These are not a viable option in terms of sustained crop production and as a result sustained crop production and as a result cultivating them accelerates the process cultivating them accelerates the process of desertification.of desertification.

OvergrazingOvergrazing

Places pressure on certain grazing areas Places pressure on certain grazing areas particularly around wells, lakes and rivers.particularly around wells, lakes and rivers.

The concentration of herds in these areas The concentration of herds in these areas results in vegetation being stripped down results in vegetation being stripped down to its roots, leaving soil exposed.to its roots, leaving soil exposed.

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

Deforestation (1)Deforestation (1)

Since 1990, 90% of forests have been Since 1990, 90% of forests have been cleared in the Ethiopian Highlands.cleared in the Ethiopian Highlands.

Deforestation removes the binding effect Deforestation removes the binding effect of tree roots and prevents the trees from of tree roots and prevents the trees from reducing wind speed.reducing wind speed.

The shortage of fire wood means that The shortage of fire wood means that more and more families are having to more and more families are having to resort to animal dung and crop residues resort to animal dung and crop residues for their domestic energy requirements.for their domestic energy requirements.

Deforestation (2)Deforestation (2)

The dung and crop residues would The dung and crop residues would normally be used as fertiliser so the normally be used as fertiliser so the soil is further degraded as it is soil is further degraded as it is deprived of essential nutrients.deprived of essential nutrients.

In the long term this will affect crop In the long term this will affect crop yields.yields.

UrbanisationUrbanisation Urbanisation has led to an increased Urbanisation has led to an increased

demand for firewood.demand for firewood.

Large areas of forest are cut down and the Large areas of forest are cut down and the wood is often turned into charcoal for ease wood is often turned into charcoal for ease of transport.of transport.

This process is extremely inefficient and This process is extremely inefficient and half of the energy of the wood is lost half of the energy of the wood is lost during conversion.during conversion.

Growth of cash cropsGrowth of cash crops

During the twentieth century some During the twentieth century some farmers in the Sahel moved away from farmers in the Sahel moved away from traditional techniques and began growing traditional techniques and began growing cash crops such as cotton and rice.cash crops such as cotton and rice.

This monoculture often combined with This monoculture often combined with inappropriate farming techniques has inappropriate farming techniques has rendered the soil infertile in many areas.rendered the soil infertile in many areas.

Physical consequences of Physical consequences of land degradationland degradation

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

In the last 50 years, 65 million hectares of the Sahel have turned to

desert.

In Sudan the Sahara has advanced by

100km in 17years. Desertification is now estimated to be

spreading at a rate of 1.5 million hectares per year

in the Sahel.

Physical ConsequencesPhysical Consequences

Rills and gulliesRills and gullies

Loss of topsoilLoss of topsoil

SalinisationSalinisation

Social and economic Social and economic consequences of land consequences of land

degradationdegradation Malnutrition and starvation – The Malnutrition and starvation – The

failure of crops year after year leads failure of crops year after year leads to starvation and death eg: Sudan to starvation and death eg: Sudan and Ethiopia (mid 1980’s).and Ethiopia (mid 1980’s).

Cash crop farming can also lead to Cash crop farming can also lead to malnutrition. malnutrition.

MigrationMigration

Many people have now migrated Many people have now migrated away from the Sahel.away from the Sahel.

This has led to the loss of traditional This has led to the loss of traditional farming techniques and in some farming techniques and in some cases (eg: northern Niger) a cases (eg: northern Niger) a demographically imbalanced rural demographically imbalanced rural population.population.

Dependence on external Dependence on external supportsupport Where the effects of land Where the effects of land

degradation and drought have been degradation and drought have been the most acute, people have come to the most acute, people have come to rely on food and other aid sent from rely on food and other aid sent from other countries, eg: the band aid other countries, eg: the band aid campaign of 1983.campaign of 1983.

This can lead to This can lead to over dependencyover dependency on external help.on external help.

Access to education and Access to education and healthcarehealthcare

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

Solutions to Solutions to RLDRLD

Solution 1 : IrrigationSolution 1 : Irrigation

There have been several expensive There have been several expensive irrigation schemes where rivers have irrigation schemes where rivers have been dammed and reservoirs been dammed and reservoirs formed.formed.

The water from the reservoirs is then The water from the reservoirs is then taken by canals to irrigate large taken by canals to irrigate large areas of farmland.areas of farmland.

The Gezira SchemeThe Gezira Scheme

In Sudan the Gezira scheme allows In Sudan the Gezira scheme allows one million hectares of land to be one million hectares of land to be irrigated using water from the White irrigated using water from the White Nile and Blue Nile.Nile and Blue Nile.

The GeziraThe GeziraSchemeScheme

The Gezira SchemeThe Gezira Scheme

Advantages

Crops grow even though there is little

rain

Farmers can have two

harvests a year

Farmer income has increased

considerably

Cotton is grown for

export

Wheat is grown for

food

150 000 people are

now employed there.

The Gezira SchemeThe Gezira Scheme

Disadvantages

Very expensive

The reservoir flooded land which had previously

been used by local farmers

Only helped people in one

small area of the country

Solution 2 - TerracesSolution 2 - Terraces

There are over 200 000 kilometres of There are over 200 000 kilometres of terraces in Ethiopia.terraces in Ethiopia.

They help trap water, stopping it They help trap water, stopping it from washing the soil away.from washing the soil away.

Solution 3 – AfforestationSolution 3 – Afforestation Planting new trees helps to bind the soil, Planting new trees helps to bind the soil,

and also provides shade, windbreaks, and also provides shade, windbreaks, nutrients and fuel for families.nutrients and fuel for families.

Depending on the species planted the Depending on the species planted the trees may also provide nuts and fruit for trees may also provide nuts and fruit for humans and animals.humans and animals.

Tree planting needs to be sustainable if it Tree planting needs to be sustainable if it is to be successful in the Sahel.is to be successful in the Sahel.

Solution 4 – Stone linesSolution 4 – Stone lines

In Burkina Faso and other Sahel countries local In Burkina Faso and other Sahel countries local people have built lines of stones along contours people have built lines of stones along contours on their sloping farmland.on their sloping farmland.

These stone lines trap run-off after heavy rain so These stone lines trap run-off after heavy rain so that the soil is not washed away.that the soil is not washed away.

Crops also grow much better in the deeper soil Crops also grow much better in the deeper soil behind the stones.behind the stones.

This method requires a lot of labour but is cheap This method requires a lot of labour but is cheap and simple to work.and simple to work.

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

Other methods (1)Other methods (1)

Managed grazing areasManaged grazing areas

Reduced herd sizesReduced herd sizes

Other methods (2)Other methods (2)

EducationEducation

Fuel efficient stovesFuel efficient stoves