(a) Of what importance is the Aswan High Dam to the Nile Basin? (b) Identify four problems resulting from the construction of the dam.

(a) Importance of the Aswan High Dam to the Nile Basin

• Hydro-electric power: the dam generates large amounts of electricity for Egypt's homes and industries, promoting industrial development.
• All-year irrigation: stored water in Lake Nasser provides perennial irrigation, allowing two or three crops a year and the reclamation of desert land for farming.
• Flood control: it controls the annual Nile floods, preventing destructive floods in wet years.
• Water storage against drought: the reservoir stores water for use in dry years, giving a reliable water supply.
• Other benefits: improved navigation on the river, a fishing industry on Lake Nasser, and tourism at the dam and lake.

(b) Four problems resulting from the construction of the dam

• Loss of fertile silt: the dam traps silt behind it, so farmland downstream no longer receives the natural fertilising mud and farmers must buy artificial fertilizers.
• Displacement of people and loss of sites: the reservoir flooded land, displacing the Nubian people and threatening ancient monuments (Abu Simbel had to be moved).
• Increased evaporation and salinity/waterlogging: high evaporation from Lake Nasser wastes water, and continuous irrigation causes salinity and waterlogging of soils.
• Spread of disease and coastal erosion: the still water encourages bilharzia (schistosomiasis) and malaria, and the loss of silt has caused erosion of the Nile delta coast and a decline in Mediterranean sardine fishing.