Drainage is the natural or artificial removal of a surface’s water and sub-surface water from an area with excess of water. The internal drainage of most agricultural soils is good enough to prevent severe waterlogging, but many soils need artificial drainage to improve production or to manage water supplies.

The removal of excess water either from the ground surface or from the rootzone, is called drainage. Excess water may be caused by rainfall or by using too much irrigation water, but may also have other origins such as canal seepage or floods.