Assess the relative importance of the roles of water and wind in shaping desert landscapes.

AO1 – Processes and landforms associated with water and wind in deserts.

AO2 – Application of process to creation of the landforms and landscapes should address the ‘relative’ dimension.

Responses are required to use their knowledge and understanding in order to analyse and evaluate the two types of process relative to each other and how these create contrasting landforms in arid landscapes.

Notes for answers

There must a clear engagement in the ‘relative importance’ dimension of the question. This is an opportunity for responses to show understanding of the emerging importance of the role of water in landform development, weathering and vegetation coverage.

AO1

Knowledge of the processes associated with water in deserts – exogenous, endoreic and ephemeral rivers; the episodic role of water; sheet flooding, channel flash flooding. There should be clear consideration of the role of water in shaping desert landscapes.
Knowledge and understanding of the processes associated with wind in deserts – erosion: deflation and abrasion; transportation; suspension, saltation, surface creep, deposition. There should be clear consideration of the role of wind in shaping desert landscapes.
Knowledge and understanding of the landscapes associated with the action of water – wadis, bahadas, pediments, playas, inselbergs. These features may be used to exemplify the role of water in shaping desert landscapes.
Knowledge and understanding of the landforms/landscapes associated with wind – deflation hollows, desert pavements, ventifacts, yardangs, zeugen, barchans and seif dunes. These features may be used to exemplify the role of wind in shaping desert landscapes.
Sources of energy in hot desert environments: insolation, winds, runoff. Sediment sources, cells and budgets. These sources may be used to argue either in favour of wind or water, depending upon the context of argument presented.
Geomorphological processes: weathering, mass movement, erosion, transportation and deposition. There may be some links made to the role of water and/or wind in supporting these processes.
Distinctively arid geomorphological processes: weathering (thermal fracture, exfoliation, chemical weathering, block and granular disintegration).
Exemplification through place support may be a feature in showing where contrasting processes have created contrasting landscapes.

AO2

Evaluation – The ‘relative importance’ element requires a consideration of whether water or wind is more important in the chosen landscape. There is no correct answer; this depends on the material chosen in support. Others may consider the interaction between wind and water and places where both processes act to shape the landscape. This is a legitimate approach.
Evaluation – In considering water and wind in conjunction, assessment should start to identify importance of either wind or water according to the location chosen. Case study support can be considered as application where it is specifically used to address the ‘relative roles of water and wind’ dimension of the question.
Analysis – For erosion, expect to see reference to how wind abrasional processes shape and scour the land. Yardangs and zeugens are likely to feature. Traditional views are that the action of wind has dominated the development of the desert landscape.
Analysis – For transport, expect to see reference to deflation hollows and this is likely to be linked with the creation of dunes. This should be associated with the action of wind.
Analysis – For deposition, dune formations are likely to be considered.
Analysis – Expect to see reference to the episodic role of water and the formation of wadis (dry river bed), bahadas (alluvial deposition), playa (dry lake bed), pediments (water eroded plain), inselbergs (rocky outcrops).
Analysis and evaluation – It is important to note the role of water in deserts also extends to mechanical weathering processes. Diurnal temperature variation when supported by the presence of water is much more likely to accelerate the process of exfoliation.
Analysis – It is also important to consider the role of water in desert vegetation. In deserts, evaporation outweighs water inputs, leading to the formation of salt pans left stranded on the plains. The salt lakes unsurprisingly are highly saline, with high concentrations of soluble sodium salts. There are only very specialised halophytic vegetation. In sense the evaporation of water has had a direct bearing upon the salt pan landscape, but also associated vegetation.
Evaluation – More sophisticated responses should show that the role of water has been underestimated historically, but is now considered to be prominent (or at least of equal importance) in the creation of many distinctive landforms within the desert landscape.

Level 4 Description (16–20 marks)

Detailed evaluative conclusion that is rational and firmly based on knowledge and understanding which is applied to the context of the question. (AO2)
Detailed, coherent and relevant analysis and evaluation in the application of knowledge and understanding throughout (AO2).
Full evidence of links between knowledge and understanding to the application of knowledge and understanding in different contexts (AO2).
Detailed, highly relevant and appropriate knowledge and understanding of place(s) and environments used throughout (AO1).
Full and accurate knowledge and understanding of key concepts and processes throughout (AO1).
Detailed awareness of scale and temporal change which is well integrated where appropriate (AO1).

Arid Landscape Development (AQA A Level Geography)

Topic Questions