wadis

n.gully or streambed in northern Africa and the Middle East that remains dry except during rainy season

1. The explorers crossed several wadis on their journey through the desert.
   探险家在穿越沙漠的过程中穿越了几条干涸的河床。
2. After the rainstorm, the wadi became a rushing stream.
   雨后，干涸的河床变成了湍急的溪流。