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