Study GuideGeology–Deserts and Winds1. Desert FeaturesDeserts may look simple at first glance, but they contain many unique landforms created by water,wind, and erosion. Because deserts receive very little rainfall, the way water movesacross the land isvery different from wetter regions.1.1 Streams in DesertsMost deserts do not have rivers or streams that flow all year. The climate is too dry to supportconstant water flow. Instead, many desert streams flow only occasionally.These temporary streams are calledephemeral streams. They appear after sudden rainfall and dryup soon afterward.There are a few important exceptions. Some major rivers begin in high, wet mountains and carryenough water to cross desert regions. Examples include the Colorado River in the southwesternUnited States and the Nile River in Egypt.Many deserts also haveinterior drainage systems. In these systems, streams do not flow to theocean. Instead, they empty into closed, landlocked basins. Water collects in these basins for a shorttime and then evaporates. As the water disappears, salts and other minerals are left behind, formingsalt beds and evaporite deposits.1.2 Flash FloodsEven though deserts are dry, rainfall can be intense when it does occur. Most desert rain comes fromshort but powerful thunderstorms.The ground in deserts is often hard and compact, so water cannot soak in easily. Narrow streamchannels also cannot carry large amounts of water. As a result, rainwater rushes across the surfaceassheetwash, causing sudden and dangerousflash floods.Because deserts have little vegetation, the flowing water easily erodes the soil and rock. This erosioncan carve deep gullies and steep slopes. Sometimes, the water becomes so filled with sediment thatit turns into a thickmudflow.Preview Mode
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