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Rural Land Degradation Revision

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Higher Geography Rural Land Degradation Revision Remember You must know the causes, consequences and solutions to rural land degradation in North America and in ... – PowerPoint PPT presentation

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Title: Rural Land Degradation Revision


1
Rural Land Degradation Revision
  • Higher Geography

2
Remember
  • You must know the causes, consequences and
    solutions to rural land degradation in North
    America and in Africa (north of the equator).
  • Make sure that you know some examples.

3
North America
  • The Dust Bowl
  • (Kansas, Oklahoma, North Texas)

4
Physical Causes of soil erosion
  • Relief lack of shelter (flat featureless
    plains)
  • Climate prolonged drought strong winds after
    several years of moist weather weather and
    problems of tornadoes.
  • Vegetation destruction of natural vegetation
    (grassland) which has anchored soils.
  • Sandy soils often depleted of moisture.

5
Human Causes of soil erosion
  • Overcultivation during years with plenty of
    rainfall in the 1920s marginal grassland areas
    were ploughed to increase crop production.
  • Monoculture planting only wheat or cotton
    without use of fallowing or crop rotation to
    restore soil moisture / fertility.

6
Consequences (1)
  • Environmental Topsoil blown away in huge
    duststorms (or black blizzards) the remaining
    soil was barren and infertile and therefore
    unsuitable for crop production.

7
Consequences (2)
  • Social and economic Crop failure lack of
    income for farmers as soil becomes infertile,
    farms were abandoned with unemployment amongst
    farm workers.
  • Communities broke up and local shops etc. were
    forced to close through lack of business.
  • The region was depopulated, with migration to
    find work in other states eg California.

8
Solutions
  • The US Soil conservation service was set up and
    used the following methods-
  • Anchoring the soil
  • Shelter belts
  • Fallowing
  • Diversification
  • Irrigation
  • Return marginal areas
  • Contour Ploughing
  • Strip cultivation

9
Africa North of the Equator
10
Physical causes and effects of degradation
  • Fall in the water table caused by major drought
    and use of wells roots can no longer reach
    moisture and therefore vegetation dies.
  • More frequent droughts perhaps related to
    Global Warming leaves soil vulnerable to wind
    erosion. Droughts also cause a fall in the water
    table.
  • Intermittent flash floods cause soil erosion.
  • As vegetation dies roots can no longer anchor the
    soil which in turn is easily blown away.

11
Human causes of degradation
  • Population growth a demand for more food
    requires farming on marginal land.
  • Increased demand for food has shortened the
    fallow period ie the land does not have time
    to recover or regenerate.
  • Increased demand for firewood leads to
    deforestation.
  • Water shortages has lead to the need for more
    wells, lowering the water table further.
  • As the best land is used for cash crops, marginal
    land more vulnerable to erosion is ploughed to
    grow food.
  • Overgrazing destroys the vegetation cover.
  • Poor irrigation methods lead to evaporation of
    stagnant water leaving a salty infertile crust.

12
Consequences (1)
  • Environmental As vegetation is removed the
    roots are no longer able to bind the soil
    together vulnerable to wind erosion fertile
    topsoil is blown away.
  • Land becomes infertile and barren / unproductive
    turning to desert (desertification).

13
Consequences (2)
  • Social
  • People forced to migrate as land becomes
    unproductive.
  • Conflict over land between herdsmen and farmers.
  • Males migrate to work in cities leaving villages
    with social disruption.
  • Food shortages lead to malnutrition and famine.
  • This can result in movement to refugee camps and
    abandoned villages.

14
Consequences (3)
  • Economic
  • As the land becomes unproductive, farm income
    falls.
  • Incomes are no longer able to support the
    population.
  • This results in dire poverty and a reliance in
    overseas aid.
  • Interest on loads to aid survival results in
    long-term debt.

15
Solutions
  • Restore vegetation cover
  • Self-help projects
  • Drought-resistant shrubs and grasses planted
    help bind the soil
  • Trees planted
  • Build dams
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