A-Level Geography: Hot Desert Systems and Landscapes

Hot deserts are one of the optional physical landscapes in A level Geography, set for example as 'Hot desert systems and landscapes' by AQA and as dryland landscapes by OCR. This material works through that content as a system: where deserts are and why, what energy and sediment drive them, which processes operate, and what landforms result.

It begins with aridity. You calculate the aridity index, precipitation divided by potential evapotranspiration, and place places into the UNEP classes: hyper-arid below 0.05, arid from 0.05 to 0.20 and semi-arid from 0.20 to 0.50. You then explain the causes of aridity: descending air in the subtropical high-pressure belt of the Hadley cell, distance from the sea, rain shadows and cold offshore currents.

The process section covers weathering, including thermal fracture, exfoliation and granular disintegration, and the three ways wind moves sediment: suspension, saltation and surface creep. A scenario about sandblasted fence posts shows why abrasion is concentrated within a metre or two of the ground, where saltating sand travels. You also classify desert rivers as exogenous, ephemeral or endoreic and see the episodic power of sheet floods and flash floods.

Landform questions describe features rather than naming them: yardangs and zeugen shaped by wind, desert pavements left behind by deflation, alluvial fans at the mouths of wadis, and the contrast between crescent-shaped barchans, which form where sand is scarce and the wind blows from one direction, and long seif dunes, which form where winds blow from two directions.

The last part deals with desertification in the semi-arid margins: human causes such as overgrazing, deforestation and over-abstraction alongside climate variability, its impacts on farming communities, and low-cost responses such as contour stone lines that slow runoff and trap soil.

The material offers a quiz with explanations, flashcards for processes and landforms, a printable written sheet of calculations and explanations, and an oral exam in which an examiner asks one question at a time and gives brief feedback at the end.

• Calculate the aridity index and apply the UNEP aridity classes
• Explain the atmospheric and geographical causes of aridity
• Explain desert weathering and the wind processes of erosion and transport
• Classify exogenous, ephemeral and endoreic drainage
• Identify aeolian and water-formed desert landforms and explain their formation
• Explain the causes and impacts of desertification and evaluate responses

Practice material written by Zestly, based on board specifications for the hot desert or dryland landscapes option, such as AQA A-level Geography 7037, section 3.1.2 (Hot desert systems and landscapes). Aridity classes follow the UNEP aridity index (P/PET).