Desertification (AQA A Level Geography)

False.

Soil erosion is a natural process that is made worse by human activity.

The three main physical changes contributing to desertification are:

• Lowered precipitation rates.

• Increased intensity of precipitation.

• Increased temperatures.

Overgrazing is when the number of animals grazing on land exceeds what the land can support, leading to soil degradation.

Overcultivation is growing too many crops without replenishing the soil, causing it to become exhausted.

Deforestation contributes to desertification by removing trees, leading to a loss of roots that hold the soil down, which gives rise to erosion.

A negative consequence of over-irrigation in arid regions is that it can lead to raising groundwater levels, causing salts to be dissolved and form a salty crust on the surface, creating an impermeable, infertile layer that is toxic to plants.

War contributes to desertification by destroying crops and animals, leading to famine and environmental degradation.

False.

Growth in demand for cash crops has led to the best land being used for these crops, leaving unsuitable land for general food crops, which can contribute to desertification.

The downward spiral pattern is:

Soil degradation → soil erosion → reduced agricultural output → malnutrition, famine → migration → conflict → soil degradation.

Desertification affects biodiversity through loss of topsoil, over-exploitation of resources, destruction of vegetation, depletion of water sources, and increased soil salinity.

False.

Desertification reduces sand dune formation as there is less vegetation to trap loose material.

The social impacts of desertification include:

• Dust clouds affect air quality and health.

• Reduced water supplies increase water-borne diseases.

• Forced migration.

• Disputes between herdsmen and farmers for limited land.

• Food shortages lead to malnutrition and famine.

Desertification reduces agricultural productivity, leading to long-term declines in crop yields, livestock yields, plant standing biomass, and plant biodiversity.

Intermediate technology is a middle ground between low- and high-tech farming methods, using accessible and appropriate technology to help people cope with natural changes and prevent further degradation.

Diguettes are a line of stones laid along the contours of sloping farmland to catch rain, allow water to seep into the soil, prevent soil erosion, and retain organic matter.

Agroforestry combines agriculture with forestry, which decreases deforestation, provides shade, increases infiltration and interception, reduces soil erosion, and adds nutrients to the soil.

A water-spreading weir is a structure that gently spreads available water further across the land, reducing soil erosion from runoff when it rains.

False.

Desertification is a very difficult process to reverse, even if rainfall increases. The environment can start to recover with increased rainfall, but it's a slow process.