1. The natural or artificial removal of surplus surface and ground water and dissolved salts from any area in order to enhance crop growth. In the case of natural drainage the excess waters flow from fields to lakes, swamps, streams and rivers. In an artificial system surplus ground or surface water is removed by means of subsurface or surface conduits, artificial or natural. Used as an instrument to control salinity, ponding and waterlogging. Choudhury and Jensen (1997)
2 . The removal of excess water from the land surface and/or the upper soil layer to make non-productive wet land productive and wet land more productive. Choudhury and Jensen (1997)
See: Watershed, Basin