Wadi

A valley or river channel in an arid region, usually dry but carrying water during rainfall or seasonal floods.

Flash flood: A sudden flood produced by intense rain, often in a dry drainage basin. Brief, powerful floods carry water through wadis that are dry most of the year.
Arid climate: A climate with persistently low precipitation relative to potential evaporation. Low rainfall leaves most wadi channels dry between storms.
Aquifer: A permeable underground layer that stores and transmits groundwater. Wadi sediments can store floodwater and recharge nearby aquifers.
Dry valley: A valley without a permanent stream, often formed or modified by intermittent water flow. Wadis are a prominent dry-valley form in arid regions.
Erosion: The wearing away and transport of rock or soil by water, wind, ice, or gravity. Repeated floods carve wadi channels and move sediment downstream.
Drainage basin: An area of land where water drains toward a common outlet. A wadi collects runoff from its contributing basin during rain.
Groundwater recharge: The movement of water from the surface into underground aquifers. Infiltration from wadi floods can replenish groundwater in dry regions.
Gully: A channel cut into soil by concentrated water erosion. Small channels can develop into larger drainage features within wadi systems.
Alluvial fan: A fan-shaped deposit of sediment formed where a stream emerges onto flatter ground. Wadi floods often spread gravel and sand into fans at mountain fronts.
Runoff: Water that flows over land rather than soaking into the ground. Storm runoff supplies the short-lived flows in wadi channels.

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