Desertification (AQA GCSE Geography)

Causes of Desertifiication

• Desertification is caused by both natural factors and human activities

• Desertification threatens approximately 20% of the world's population

• It can be argued that many of the natural causes may be made worse by human activity and climate change 

Comparison Between Natural and Human Causes

• In areas such as Kenya, both human and natural factors lead to desertification

• Grazing patterns and traditional lifestyles mean that: 

  • Nomadic Masai farmers have been forced to use smaller and smaller areas of land for grazing

    • This results in overgrazing, which removes the vegetation

    • The soil no longer has protection from the wind and rain which leads to soil erosion and desertification

• Population growth increases the demand for food and fuelwood

  • Kenya's population is predicted to double between 2010 and 2030

  • This leads to over-cultivation and deforestation

  • Deforestation:

    • Reduces the amount of nutrients returned to the soil

    • Exposes the soil to wind and rain

  • This further increases soil erosion, leading to desertification

• In Kenya increasing temperatures and more irregular rainfall are natural causes of desertification

• However, these could be the result of the enhanced greenhouse effect (human cause) leading to climate change 

Strategies to Reduce the Risk of Desertification

• Halting and reversing desertification means tackling the causes

• There are a variety of possible methods that can be used

Water management

• Contour stones or bunds can be used to increase infiltration

• Earth dams can be used in the wet season to store water

• Drip irrigation can be used to water crops more efficiently 

Education

• Education including:

  • Sustainable farming methods including agroforestry and crop rotation, which help to keep the soil healthy

  • Family planning to reduce population growth

Agroforestry 

• This combines agriculture with forestry, which means some trees remain, which:

  • Decreases deforestation

  • Provides shade as well as increasing infiltration and interception, which reduces soil erosion

  • Provides organic matter from the trees and adds nutrients to the soil

Afforestation

• Tree planting, such as the Great Green Wall across the Sahel, helps to reverse desertification in several ways:

  • The roots help to bind the soil together reducing soil erosion

  • The canopy offers shade helping to prevent the soil from drying out and also reducing soil erosion from rainfall landing directly on the soil

  • Nutrients in the soil are replaced by falling leaves and branches

  • The trees increase animal and insect activity which helps improve soil quality

Contour stones or bunds

• These help to reduce soil erosion by:

  • Preventing the soil from being blown or washed away

  • Reduce overland flow

  • Ensuring that dead organic matter stays in one place and can decompose adding nutrients to the soil

• Additionally they increase infiltration of water into the soil