A dry gully is often referred to as a arroyo or a wash.
gully
arroyo
Arroyo
arroyo
a wash
Arroyo ; " A deep gully cut by an intermittent stream; a dry gulch. "
Arroyo, gully, wash or wadi depending on the area of the world and local language customs.
A wash is an arroyo, or gully or wadi that is normally dry but quickly fills with water after a heavy rain.
gully erotion is something that makes trenches
Depending upon the area of the world it may be called an arroyo, a wash, a gully, a gulch or a wadi.
The plural of gully is gullies. As in "this is the gullies".