The deep water can cause both a ditch or a gully. The formation of a gully or a ditch is dependent on the topography of the land and the speed of the flowing water.
arroyo - deep gully cut by an intermittent stream.
Often times a deep ditch carved over time by running water is called a trench. It can also be called a ditch.
The deepest part of a river or waterway channel is called the THALWEG. It is an imaginary line that connects the deepest parts of the river or waterway channel.
Miscellaneous
Yes. There are numerous justifications both for and of Darwin's theory. It beautifully and simply explains the diversity of the tremendously complex biological world in which we find ourselves. Darwin's theory of evolution boils down to just two simple rules. These are that replication is imperfect (variety is introduced into an organism's offspring), and survival is preferential (changing environmental conditions discourage replication of "less fit" individuals). These two rules can be further summarized as: Random mutation plus natural selection. RM+NS. Evolution is the heart surrounding these initials, carved deep into the bark of the tree of life.
arroyo - deep gully cut by an intermittent stream.
It's a gully. Rills are smaller ditches cut by running water, but can be plowed over. Once the ditch is so deep it can't be plowed over, it's a gully.
The difference between a gully and a ditch is that a gully is a deep ditch. Also a ditch is a lower grade in the earth where water collects and pools.
Canyon
Often times a deep ditch carved over time by running water is called a trench. It can also be called a ditch.
A canion.
When the cow fell into the gully, it took a team of firemen and heavy lifting gear to rescue it.
gully
It is called a moat
A deep gully or valley.
Another word for a deep ditch that is dug around a castle is a moat. You could call it a trench, or you could fill it full of water and call it a moat.
chasm