(a) Draw a sketch map of Nigeria. On the map, show and name: (i) a delta (ii) a man-made lake; (iii) a confluence town; (iv) the Jos Plateau. (b) Outline an...

(a) Sketch map of Nigeria

Key locations shown: Niger Delta, Kainji Lake, Lokoja (confluence town), and Jos Plateau.

(b) Physical factors limiting river transportation in Nigeria

1. Waterfalls, rapids and cataracts: These interrupt river channels and prevent the smooth movement of vessels.
2. Seasonal fluctuation in river volume: Water levels are low in the dry season, making channels shallow, while some rivers flow swiftly and flood during the rainy season.
3. Silting and sand bars: Deposition of silt and sand reduces the depth of river channels and obstructs boats.

Other acceptable factors include floating water weeds, debris, narrow channels and gorges, deltaic river mouths, and short river courses.

(c) Solutions to the limiting factors

1. Dredging: River beds should be dredged regularly to remove silt and sand bars and maintain a deep navigable channel.
2. Construction of dams, locks and canals: Dams regulate water flow, while locks or canals enable vessels to bypass rapids, cataracts and waterfalls.
3. Clearing obstructions: Water weeds and floating debris should be removed continuously from navigable channels.

Other measures include channelization, the use of small or light vessels on shallow rivers, and construction of road or rail routes around major rapids and waterfalls.