When the early farmers moved down from the hills into the valleys of the Nile, Tigris, and Euphrates Rivers, they had to develop the technology of irrigation. The freshwater rivers passed through lands essentially barren due to the lack of rainfall. Through irrigation, water could be removed from the rivers and spread on the nearby land, making it suitable for farming.
Irrigation increases Food production in Grasslands, Plains, Deserts, and Hills. Only squares vertically or horizontally adjacent to water (Oceans or Rivers) or another irrigated square can be irrigated. After the discovery of Refrigeration, terrain squares can be double-irrigated to create farmland. Settlers and Engineers can be ordered to irrigate by pressing the "I" key, or by selecting "Build Irrigation" from the Orders menu.
|Civilization II Tile Improvements|