If you were asked to close your eyes and think of a dryland river, what would come to mind? You might see images of wide, sandy channels and bars with sparse vegetation, completely dry channels, or a sudden, debrisladen flood causing dramatic channel erosion. The words ‘braided’, ‘ephemeral’, ‘flash flood’ or ‘unstable channel’ might accompany these images. If so, then your thinking would be in line with typical textbook descriptions of dryland rivers (Box 1).
Many of the world’s dryland rivers match these descriptions, particularly in regions where convective thunderstorms feed short, steep rivers draining from tectonically active upland catchments. Examples of these types of dryland rivers, with multiple channels dividing and rejoining around shifting bars (Photograph 1), can be found in parts of the southwest USA, Middle East, and the Mediterranean, where pioneering dryland research was done.
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