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Dryland Landscapes

Fluvial and aeolian processes in the desert

  • 2 things to know
  • Component 01

Overview

Recall questions on desert runoff, ephemeral streams, exotic rivers and endoreic drainage, flash flood hydrographs and transmission losses, sediment loads, deflation and the Qattara Depression, wind abrasion, saltation, surface creep and suspension, and the wind speed needed to move sand.

What you need to know

Answer each one before you reveal it.

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Key term

Why do deserts produce so much runoff from so little rain?

Key term

What is an exotic river? Give one example.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Why do deserts produce so much runoff from so little rain?

    Model answer

    Rain arrives in short intense bursts onto ground that is bare, crusted and often baked hard or capped by duricrust, so the infiltration rate is far below the rainfall intensity and the excess runs off.

  2. 2

    Define the term ephemeral stream.

    Model answer

    An ephemeral stream is a watercourse that flows only for a short time during and after rainfall and lies dry for most of the year.

  3. 3

    What is an exotic river? Give one example.

    Model answer

    An exotic river is one that rises in a wetter region outside the desert and flows across it on water gathered elsewhere; the Nile is an example.

  4. 4

    What is an endoreic drainage system?

    Model answer

    An endoreic drainage system is one with no outlet to the sea, in which rivers end in an inland lake, a playa or the desert sands.

  5. 5

    Describe the shape of a flash flood hydrograph.

    Model answer

    It has a very short lag time, an extremely steep rising limb to a high peak discharge, and then a rapid fall back towards zero.

  6. 6

    What are transmission losses, and why do they matter in a desert?

    Model answer

    They are the water lost from a channel by seepage into the dry bed and by evaporation, and they can be so great that discharge falls downstream and the flood dies out before reaching any lake or sea.

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AThe lower quartile is the 2nd value, 11 cm.
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