Write a geographical account of irrigation agriculture in the Niger Basin under the following headings: (a) Areas (b) Methods (c) Crops (d) Problems (e) Sol...

Irrigation Agriculture in the Niger Basin

Irrigation agriculture is the artificial supply of water to crops, especially during the dry season. It is important in the Niger Basin because much of the basin has a long dry season and unreliable rainfall.

(a) Areas

1. The inland delta and Office du Niger scheme in Mali, especially around Ségou, Macina and Mopti. This is a major irrigated rice-growing area.
2. The Sokoto-Rima Valley in north-western Nigeria, including the Bakolori and Goronyo irrigation schemes.
3. The Kano River valley in northern Nigeria, supplied principally from the Tiga and Challawa Gorge reservoirs.
4. The Niger flood plains and fadama lands in Nigeria, including the Jebba-Bacita area, as well as low-lying valleys along the Niger and Benue rivers.

(b) Methods

1. Basin or flood irrigation: river floodwater is admitted into enclosed basins or flood plains and retained for crop production as the water recedes.
2. Perennial irrigation: dams, reservoirs, barrages and canals store and distribute water throughout the year. Examples include Bakolori Dam and Tiga Dam.
3. Pump or lift irrigation: diesel or electric pumps lift water from rivers, reservoirs, wells or boreholes into channels or pipes leading to farms.
4. Shaduf and manual methods: water is lifted in buckets, calabashes or shadufs on small river-bank plots.
5. Sprinkler and furrow irrigation: water is sprayed through sprinklers or led along shallow furrows, particularly on organised schemes and vegetable farms.

(c) Crops

The main irrigated crops are rice, sugar cane, cotton, wheat, maize, sorghum, millet, barley, groundnuts and vegetables such as onions, tomatoes and peppers.

(d) Problems

1. Very high capital cost of constructing dams, canals, pumps and drainage works.
2. Silt deposition in reservoirs and canals reduces their water-holding capacity and water flow.
3. Rapid growth of aquatic weeds blocks canals and restricts irrigation water.
4. Excessive evaporation and poor drainage cause salinisation and waterlogging of soils.
5. Seasonal rivers, drought and low reservoir levels may produce inadequate water supply.
6. Flooding may destroy crops and erode irrigated fields.
7. Stagnant water encourages malaria, bilharzia and other water-borne diseases.
8. Dam construction may displace settlements and farmlands, while dam failure can cause serious flooding.

(e) Solutions

1. Provide adequate government funding, credit and technical support for irrigation projects and their maintenance.
2. Dredge river channels and desilt reservoirs and canals regularly.
3. Clear aquatic weeds continuously and maintain canal banks and gates.
4. Construct and maintain proper drainage channels; use controlled watering to prevent waterlogging and salt accumulation.
5. Store floodwater in reservoirs and small dams, and use boreholes or pumps where appropriate.
6. Build or widen flood-control channels, embankments and spillways to protect farms from flooding.
7. Provide medical care, safe water, sanitation and mosquito control in irrigation settlements.
8. Use improved dam-construction technology and resettle people displaced by irrigation projects adequately.