Artificial Basin Irrigation

Artificial irrigation was established by the 1st Dynasty (Butzer, 1976). This included deliberate flooding and draining using sluice gates and water contained by longitudinal and transverse dikes. Artificial irrigation increased the area of annual cropland in relation to the flood stage; retained water in the basin after smaller floods; and allowed second and even third crops in some basins. This form of water management, called basin irrigation, consisted of a network of earthen banks, some parallel

Fig. 3.3 Plan of basin irrigation. (A) head of basin canal, (B) siphon of siphon canal, (C) High land under sorghum, (D, E) basins, (F, G) regulators, (H) transverse dike, (I) longitudinal dike (modified after Willcocks and Craig, 1913 And Said, 1993)

To the river and some perpendicular to the river that formed basins of various sizes. Floodwaters were diverted into the basins where the water was allowed to saturate the soil with the remaining water drained off to a down-gradient basin or to a canal. After the draining process was completed in a basin, crops were planted. King Menes, the founder of the first dynasty in 3100 B. C. traditionally has been known as the first to develop a major basin irrigation project. Basin irrigation was carried out on a local scale as opposed to being centrally managed on a national scale.

Artificial basin irrigation was based upon the inundation of the Nile floodplain starting in early August. The floodplain was divided into basins ranging in size from 2000 feddans (1 feddan = 4,200 m2) in the upper part of Egypt to 20,000 feddans in the Nile delta (Said, 1993). Figure 3.3 Illustrates the concept of basin irrigation in which the basins were supplied with water by feeder canals. The bed level of the feeder canal was midway between low Nile and ground level with a natural downstream slope less than the slope of the Nile. Each canal supplied water to an average of eight basins arranged in succession. Dikes (levees) separated the basins with controls (masonry regulators) on the earthen embankments to control the flow of water into the basin. Average depths of water in the basins varied according to the local flood volume and stayed in the basins between 40-60 days after which the basins were drained (Said, 1993). The basins were very level as a result of the water laden alluvium that deposited in the basins. During years of low flow in the Nile basins were drained into the next downstream basin instead of back to the river.