A wadi is a river valley or a wet, ephemeral riverbed typically found in desert regions. While many wadis contain water only during periods of heavy rain, some specific locations, such as Wadi Bani Khalid and Wadi Mawr, maintain year-round water flow.
These geographical features are located on gently sloping, nearly flat parts of deserts, often beginning on the lowest portions of alluvial fans and extending toward inland sabkhas or dry lakes. Because permanent channels rarely exist due to a lack of continual water flow, water frequently percolates into the stream bed. This process causes an abrupt loss of energy and results in vast deposition, sometimes creating sediment dams that can alter stream patterns during subsequent flash floods.