A ditch is a small channel and serves as temporary rainwater retention, transportation, and infiltration. A ditch can contain water or can stand dry.
A rainwater ditch has multiple functions. It retains rainwater after a heavy downpour but it also stores water entering the ditch from a rain pipe or from paved areas in public space. The water can then infiltrate into the ground or be transported to a near channel or pond.
Ditches can be designed to facilitate infiltration or to provide green space.
By their green appearance, ditches can be integrated readily into green verges or the roadside. But they need extra space, and need maintenance to prevent silting up. With a clay soil rainwater stays longer in the ditch.
Because ditches can stand dry, plants should be used that survive dry as well as wet conditions. Examples are Siberian iris, Joseph’s coat, loosestrife, and lady’s mantle.
A green planted ditch contributes to evaporation and by that has a cooling effect; it positively affects biodiversity.