Agriculture in the prehistoric Southwest
After the Hohokam disappeared, Spanish explorers of the 16th century noted the use of canal irrigation in only two areas of the Southwest: eastern Sonora, primarily practiced by the Opata and Lower Pima, and among the Pueblos of northern New Mexico. Irrigation by the Opata and Pueblos had different objectives. In Sonora, with a long growing season, two crops of maize a year were grown in river valleys. The spring crop during the dry season was dependent upon irrigation; the summer and fall crop during the rainy season utilized irrigation to supplement rainfall. The necessity of irrigation probably required a high level of social organization. In New Mexico, with only one crop of maize per year possible, irrigation was supplemental and the lesser dependence on irrigation implies less social organization than in Sonora.
Agriculture in Sudan
The waters of the Nile in Sudan have been used for centuries for traditional irrigation, taking advantage of the annual Nile flood. Some use of this method still continued in the early 1990s, and the traditional shaduf (a device to raise water) and waterwheel were also used to lift water to fields in local irrigation projects but were rapidly being replaced by more efficient mechanized pump systems. Among the first efforts to employ irrigation for modern commercial cropping was the use of the floodwaters of the Qash River and the Baraka River (both of which originate in Ethiopia) in eastern Sudan to grow cotton on their deltas. This project was started in the late 1860s by the Egyptian governor and continued until interrupted by the turbulent period of the 1880s, leading to the reconquest of the country by the British in 1899. Cultivation was resumed in 1896 in the Baraka Delta in the Tawkar area, but in the Qash Delta it only resumed after World War I. Between 1924 and 1926, canals were built in the latter delta to control the flood; sandstorms made canals unfeasible in the Baraka. Between the 1940s and the 1970s, various projects were developed to irrigate land. In 1982 both deltas yielded only one crop a year, watered by the flood. Adequate groundwater, however, offered the eventual possibility of using pump irrigation from local wells for additional cropping or for supplementing any flood shortages.