Wadi
Wadi (), alternatively wād (), Maghrebi Arabic Oued, is the Arabic term traditionally referring to a river valley. In some instances, it may refer to a wet (ephemeral) riverbed that contains water only when heavy rain occurs. Arroyo (Spanish) is used in the Americas for similar landforms. Etymology The term is very widely found in Arabic toponyms. Some Spanish toponyms are derived from Andalusian Arabic where was used to mean a permanent river, for example: Guadalcanal from wādī al-qanāl (, "river of refreshment stalls"), Guadalajara from wādī al-ḥijārah (, "river of stones"), or Guadalquivir, from al-wādī al-kabīr (, "the great river"). General morphology and processes Wadis are located on gently sloping, nearly flat parts of deserts; commonly they begin on the distal portions of alluvial fans and extend to inland sabkhas or dry lakes. In basin and range topography, wadis trend along basin axes at the terminus of fans. Permanent channels do not exist, due to lack of continual water flow. They have braided stream patterns because of the deficiency of water and the abundance of sediments. Water percolates down into the stream bed, causing an abrupt loss of energy and resulting in vast deposition. Wadis may develop dams of