Theory question 108
Agriculture, Fishing and Lumbering(a) Name any four irrigation areas in the Nile Valley. (b) Describe the perennial method of irrigation in the Nile Valley. (c) Explain any four problems created by irrigation in the Nile Valley.
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(a) Gezira-Managil scheme (Sudan); Nile delta; Fayum depression; Kom Ombo; Aswan area; Esna; New Valley (Toshka); Khashm el Girba.
(b) Dams and barrages (Aswan High Dam, Sennar, Jebel Aulia) store water; water is released all year through main canals, branch canals and field channels; pumps lift water where needed; allows two or three crops a year (cotton, wheat, rice, sugarcane).
(c) Salinisation and waterlogging of soils; loss of fertile silt (trapped behind dams) so more fertilizer needed; spread of bilharzia and malaria; coastal erosion of the delta; weeds blocking canals; evaporation losses; displacement of people (Nubians); high cost.
Explain each problem, not just name it.