Source : Webster's Revised Unabridged Dictionary (1913)

Gully \Gul"ly\, v. t. [imp. & p. p. {Gullied}; p. pr. & vb. n.
   {Gullying}.]
   To wear into a gully or into gullies.

Source : WordNet®

gullied
     See {gully}

gully
     n : deep ditch cut by running water (especially after a
         prolonged downpour)
     [also: {gullied}]