(a) Draw a sketch map of Africa. On the map, mark and name: (i) the Rivers Niger and Nile; (ii) two areas of irrigation agriculture along each river. (b) Ou...

(a) Sketch map of Africa showing the rivers and irrigation areas

Key locations marked on the sketch map:

• River Niger: Office du Niger irrigation scheme, Mali; and Baguinéda irrigation area, Mali.
• River Nile: Gezira irrigation scheme, Sudan; and the Nile Delta irrigation area, Egypt.

(b) Contributions of irrigation agriculture to the Gezira Scheme, Sudan

1. It provides water for farming throughout the year and permits continuous or multiple cropping.
2. It increases the production of food crops such as wheat, sorghum and vegetables for the growing population.
3. It provides employment and income for farmers, farm labourers, traders and transport workers.
4. It produces cash crops, especially cotton, which supply raw materials to industries and earn foreign exchange.
5. It provides revenue to the government through taxes, export duties and sales of agricultural produce.

(c) Problems facing irrigation agriculture in the Gezira Scheme

1. Salinisation and waterlogging: high evaporation and poor drainage leave salts in the soil and reduce soil fertility.
2. High cost: canals, dams, pumps and irrigation equipment are expensive to construct, operate and maintain.
3. Silting: silt deposited in canals and reservoirs reduces their depth and carrying capacity.
4. Water-borne diseases: stagnant water in canals encourages diseases such as bilharzia and malaria.
5. Fluctuation in water supply: low river flow or drought may reduce the amount of water available for irrigation.