ABSTRACT
Irrigation is the addition of water to the soil to produce near optimum soil moisture conditions for crop growth in regions of water scarcity (Rydzewski and Ward 1989). Irrigated agriculture appears to have commenced on a small scale soon after the domestication of cereals in the Middle East. This domestication probably began about 12, 000 years ago, yet by 10, 000 years ago archaeological excavations at Jericho have revealed that groundwater from a nearby spring was being used for irrigation (Kenyon 1969–70). However, irrigated agriculture is perhaps most closely associated with the development of urban civilisations in the great river valleys of the Old World, including the Tigris-Euphrates, Indus and Nile (Adams 1965; Wittfogel 1957). The key factor is that irrigation of these huge floodplains using large-scale diversion structures and canals generated the wealth necessary for the construction of complex urban systems and the founding of empires.
