Wash (landform)

An arroyo (/əˈrɔɪoʊ/; Spanish: [aˈroʝo], "brook"), also called a wash, is a dry creek, stream bed or gulch that temporarily or seasonally fills and flows after sufficient rain.Flash floods are common in arroyos following thunderstorms. In Latin America any small river might be called an arroyo, even if it flows continually all year and is never dry. The Arabic terms rambla or wadi are used in North Africa and Southwest Asia. Arroyos provide a water source to desert animals.

The desert dry wash biome is restricted to the arroyos of the southwestern United States.

Arroyos can be natural fluvial landforms or constructed flood control channels. The term usually applies to a sloped or mountainous terrain in xeric and desert climates. In addition: in many rural communities arroyos are also the principal transportation routes; and in many urban communities arroyos are also parks and recreational locations, often with linear multi-use bicycle, pedestrian, and equestrian trails. Flash flooding can cause the deep arroyos or deposition of sediment on flooded lands. This can lower the groundwater level of the surrounding area, making it unsuitable for agriculture. However a shallow water table lowered in desert arroyo valleys can reduce saline seeping and alkali deposits in the topsoil, making it suitable for irrigated farming.

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