Dynamic drylands

Understanding the processes at work

Dryland landscapes and landforms on Earth have been studied for decades, and this research is now being used in NASA’s exploration of Martian sand dunes. In this article Abi Stone shows how the diversity of dryland landscapes can be understood by looking at them as systems, and studying the processes involved in their inputs, stores, flows and outputs

Abi Stone

Around one third of the land on Earth can be classified as dryland (Figure 1), where there is a waterbalance deficit (Box 1). At A-level the focus is on warm drylands, but the definition includes cold polar deserts experiencing only a little snowfall. The four main reasons for aridity in warm deserts (see GEOGRAPHY REVIEW Vol. 28, No. 2) are:

■ dry subsiding air in high-pressure zones beneath the descending limbs of the Hadley Cells