Spoiler warning: Plot and/or ending details follow.
Irrigation is a technique for the distribution of water. It is heavily used in agriculture to provide water to plants and livestock animals.
Irrigation was used on Tarsus IV to provide water to hydroponic farms. (DSC novel: Drastic Measures)
While suffering from amnesia, Captain James T. Kirk designed an irrigation system for a village on Amerind to provide water for the village's fields. Had this system been implemented it would have doubled the amount of food the village could have produced. (TOS episode: "The Paradise Syndrome")
The colonists on New Bajor built an extensive irrigation system prior to the destruction of the colony by the Jem'Hadar. (DS9 episode: "The Jem'Hadar")