Water Table Management: Subirrigation and Controlled Drainage

This chapter discusses the objectives, theory, and some aspects of the application of water table management via subirrigation and controlled drainage. Water table management systems may be operated in drainage, controlled drainage or subirrigation modes. The objectives of a water table management system generally include all of the traditional objectives of conventional drainage systems plus additional objectives of conserving soil water, increasing yields by reducing or eliminating stresses caused by deficit soil water conditions, and other pollutants via drainage water. A major objective of a subirrigation system is to deliver sufficient water to the crop root zone to satisfy evapotranspiration demands. The systems may be designed to operate in either steady-state or transient modes. In the transient mode, water is pumped into the drains and maintained at a relatively high elevation until the water table is raised, usually close to, or even within, the root zone.