Wadi (noun)

1. A valley or gully that is dry except during the rainy season.
2. A streambed in a desert or semi-arid region that is dry except during the rainy season or when fed by a nearby source.

Origin:

From arabic wādī.

Examples:

1. The nomads followed the wadi in search of water.
2. The wadi was dry and rocky, but during the rainy season it filled with water.
3. The plants in the wadi were adapted to survive long periods of drought.
4. The wadi was used as a trade route between the desert towns.
5. The wadi was the site of an ancient civilization, now only ruins remain.