Subsurface drains

Description of practice

Subsurface drains remove excess groundwater. Most commonly, they are used to drain water from the rootzone to improve aeration, crop production and bearing capacity. Specific drainage systems can also help to regulate CO2 emissions and salinity.

Examples of how to use subsurface drains		Further information (see Note below)
	Submerged drains Submerged drains are installed in grassland on peat soils to decrease soil subsidence and CO₂ and N₂O emissions and to maintain suitable groundwater levels for grassland production and grazing. They can be used to allow an inflow of water in summer (to avoid peat oxidation) or outflow in the winter (to remove surplus water).	»WOCAT technology 1704
	Buried pipe drains Corrugated, flexible and perforated plastic pipelines are wrapped with filter material to improve the permeability around the pipes. These drains help to control the groundwater levels in agricultural fields.	»King Construction
	Controlled drainage A water structure is used to manage the depth of the drainage outlet, providing control over the outflow of soil water from a field, e.g. to prevent outflow during drier periods when no drainage is required.	»Drainage Contractor »SSWM
	Sub-soil drainage pipes Sub-soil perforated drainage pipes are laid in agricultural fields to prevent waterlogging and enhance infiltration. Improved salt removal is another beneficial side effect.	»WOCAT technology 1126
	Mole drains A ripper blade with a cylindrical foot (mole) is pulled through heavy clay subsoils to create an unlined channel or mole drain.	»Western Australia Government »Agriculture Victoria
	Tubewell drainage Ground water is pumped out of a specially dug tubewell to control the salinity and water table level. The amount of ground water removed is equal to the drained surplus water.	»World Water Atlas »HomeSteady

Note: Most of the Further information links are to a full description of the example in the WOCAT database. However sometimes the link may be to similar practices or a research paper. Occasionally the link is to a commercial product in which case it should be understood that this does not imply any endorsement of the product by iSQAPER.