Deserts and Rivers

Exogenous Drainage

• Exogenic rivers have a source outside of the desert.
• Most exogenous rivers are perennial (permanent).
• Some exogenous rivers flow right through a desert.
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• Example: The River Nile, Egypt
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Endoreic Drainage

• Endorheic rivers that start outside the desert but flow into an inland sea or lake rather than the sea.
• Example: The River Jordan
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Ephemeral Drainage

• Ephemeral rivers flow intermittently or seasonally after rainstorms but remain dry during the rest of the year.
• Desert lakes can also be ephemeral. Ephemeral lakes are called playas.
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Sheet Flooding

• A sheet flood is a slow moving, even flow of water over land and isn't confined to a channel.
• Depths of a sheet flood can be up to 1m.
• These floods are highly erosive.
• After intense rainfall, water is not absorbed by the impermeable soil therefore it flows down gentle slopes as sheets of water.
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Flash Flooding

• A flash flood is a sudden, strong and rapid flow of water through a channel.
• The lack of vegetation and the weathered surface means that large amounts of rock are removed in a very short time.
• Flooding allows aquifers to be recharged.
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• Flash floods occur when heavy rainfall can't infiltrate the soil, causing surface runoff.
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