Controlled Drainage

The process of managing the drainage volume and water table elevation by regulating the flow from a surface or subsurface agricultural drainage system.

Controlled drainage, also known as drainage water management, is the practice of using a water control structure to raise the depth of the drainage outlet, holding water in the field during periods when drainage is not needed. Unlike conventional free-draining systems that remove excess soil water to the drain depth, controlled drainage increases water retention and storage within the soil profile. This practice has been shown to be effective in reducing the total drainage volume and associated nutrient loads from tile-drained agriculture, while also providing an opportunity for improved crop yields in certain years. However, many factors such as drainage system design and management, soil types, and climate can all influence how an individual field performs under controlled drainage.