Wadi

Wadi (Arabic: وادي‎"wādī) "Vadi" (Hebrew: ואדי‎ "vādī)" is the Arabic and Hebrew term traditionally referring to a valley. In some instances, it may refer to a dry (ephemeral) riverbed that contains water only during times of heavy rain or simply an intermittent stream.

Etymology

The term wādī is very widely found in Arabic toponyms.

Some Spanish toponyms are derived from Andalusian Arabic where wādī was used to mean a permanent river, for example: Guadalcanal from wādī al-Qanal = "river of refreshment stalls", Guadalajara from wādī al-hidjārah = "river of stones", or Guadalquivir from al-wādī al-kabīr = "the great river". Seasonal streams, frequent in south-east Spain, are called ramblas instead.

In the Maghreb, the term wadi (wad in Maghrebi Arabic, sometimes transcribed Oued) is applied to all rivers including regular ones.

General morphology and processes

Wadis are located on the gently sloping, nearly flat parts of deserts; commonly they begin on the distal portions of fans and extend to inland sabkhas or playas. 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. Wadi show braided stream patterns because of the deficiency of water and the abundance of sediments. Water percolates down into the stream bed causing abrupt loss in energy and resulting vast deposition. Wadis may develop dams of sediment which results in change of stream patterns in the next flash flood. :)