Drainage is any system used to remove excess water from land.
Drainage can be either natural or artificial. Many areas have some natural drainage; this means that excess water flows into lakes and rivers. Natural drainage, however, is often inadequate, and artificial or man-made drainage is required.
Different Types of Drainage:
There are two types of artificial drainage: surface drainage and subsurface drainage.
Surface drainage is the removal of excess water from the surface of the land. This is normally accomplished by shallow ditches, also called open drains.
Subsurface drainage is the removal of water from the root zone. It is accomplished by deep open drains or buried pipe drains.