Ditch
A ditch with water can be used for drainage and irrigation.
With or without water it can be used as a barrier, as an alternative for a fence.
A trench is a long narrow ditch.
Types and applications include:
- Military - i.e. for trench warfare
- Geological - oceanic trench, eg Mariana Trench
- Gardening
- Archaeology - referring to an open excavation
- a temporary trench for burying a pipeline, cable, etc.