#gully  deep ditch cut by running water (especially after a prolonged downpour)
  supertype:  #valley__vale  a long depression in the surface of the land that usually contains a river
  subtype:  #arroyo  (southwestern United States) a stream or brook
  subtype:  #draw  a gully that is shallower than a ravine
  subtype:  #wadi  gully or streambed in North Africa and the Middle East that remains dry except during rainy season

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