Key Terms: Desertification (AQA A Level Geography): Revision Note

Distribution of desertification - key terms

Arid area – A region with very low precipitation, leading to limited vegetation and water scarcity.

Dryland – An area with limited water availability, including arid, semi-arid, and dry sub-humid regions; covers about 40% of Earth’s land.

Green Sahara – A period between 11,000 and 5,000 years ago when the Sahara region had vegetation, lakes, and savanna wildlife before becoming a desert.

Semi-arid area – A climate region that receives more rainfall than deserts but still experiences frequent droughts and water shortages.

Causes of desertification - key terms

Capillary rise – The upward movement of soil moisture that brings salts to the surface, contributing to soil salinisation.

Climate change – A physical cause of desertification, marked by increasing temperatures and changing rainfall patterns, intensifying droughts and soil degradation.

Deforestation – The removal of trees which reduces root structures that bind the soil, increasing vulnerability to erosion.

Desertification – The process by which fertile land becomes desert, typically due to drought, deforestation, or inappropriate agriculture.

Diguette – A line of stones placed along a slope to slow water runoff, encouraging infiltration and reducing soil erosion.

Irrigation – The artificial application of water to land for agriculture; when mismanaged, it can lead to increased salinisation and reduced soil fertility.

Land degradation – The decline in land quality due to natural or human processes such as erosion, overuse, or climate change.

Overcultivation – Growing crops repeatedly on the same land without restoring soil nutrients, leading to soil exhaustion and degradation.

Overgrazing – Allowing livestock to graze excessively on land, preventing vegetation regrowth and exposing soil to erosion.

Positive feedback loop (desertification) – A cycle where soil degradation causes vegetation loss, which further increases erosion and degradation.

Salinisation – The accumulation of salt in the soil surface due to excessive evaporation or poor irrigation practices, reducing soil fertility.

Shelterbelt – A belt of vegetation, such as shrubs and trees, planted to reduce wind speed and protect soil from erosion, often used in oasis regions.

Soil erosion – The removal of topsoil by wind or water, reducing soil quality and fertility, often linked with desertification.

Zai pit – A planting technique involving small pits filled with organic material to capture rainfall and concentrate nutrients near plant roots.

Impacts of desertification - key terms

Biodiversity loss – The decline in variety and abundance of species in an area due to habitat destruction and land degradation.

Dust storm – A weather phenomenon in which strong winds lift loose soil and dust into the air, reducing visibility and harming health.

Food insecurity – A situation where access to sufficient, safe, and nutritious food is not reliable, often worsened by reduced agricultural output due to desertification.

Fossil aquifer – An ancient underground water source that cannot be replenished naturally, used in arid areas for irrigation (e.g. the Nubian Sandstone Aquifer).

Malnutrition – A health condition caused by lack of food or nutrients, often a consequence of reduced agricultural output due to desertification.

Migration (due to desertification) – The movement of people from degraded areas in search of better living conditions, often leading to overcrowding elsewhere.

Reforestation – The planting of trees to restore vegetation cover, reduce soil erosion, and combat desertification.

Soil fertility – The ability of soil to support plant growth; declines with desertification due to erosion and salinity.

Urban pressure – The stress placed on urban areas from incoming migrants fleeing degraded land, often resulting in overcrowding and resource shortages.