(a) On an outline map of Nigeria show (i) one area having an annual rainfall of under 100cm (ii) one area having an annual rainfall of over 300cm (iii) one ...

As shown on the map above:

• Area with annual rainfall under 100 cm: the extreme north-eastern part of Nigeria around the Lake Chad Basin. An important town in this area is Maiduguri.
• Area with annual rainfall over 300 cm: the south-eastern coastal belt, especially around Calabar and the eastern Niger Delta. An important town is Calabar.

(b) Other climatic features of the area receiving over 300 cm of rainfall

• There are usually two rainfall maxima, commonly around June or July and September, with a short break in August.
• There is no completely dry month; rain falls throughout the year.
• Temperatures are high throughout the year, with an average of about \(27^\circ\text{C}\).
• The annual temperature range is small, usually about \(2^\circ\text{C}\) to \(3^\circ\text{C}\), because of the equatorial coastal influence.
• Relative humidity is very high, often above \(90\%\) in the mornings.
• Cloud cover is heavy and sunshine duration is relatively low.

(c) Vegetation associated with this climate

The vegetation is the mangrove swamp forest, also called coastal swamp forest. It occurs in the tidal, waterlogged and saline or brackish parts of the Niger Delta and along parts of the coast.

Characteristics of mangrove swamp vegetation include:

• It is a dense, evergreen forest because rainfall and humidity are high throughout the year.
• The trees are mainly broad-leaved and occur in different species of mangrove.
• The plants are adapted to waterlogged, muddy soils and salty water.
• Many trees have aerial roots, prop roots or breathing roots which help them obtain air from the swampy soil and also support them.
• Vegetation is generally low to medium in height, often about \(10\) to \(15\) m in wetter sections, though it may be shorter in more saline areas.
• Palms, reeds and coconut trees may occur along the shore and on relatively drier coastal land.
• The forest contains valuable hardwood species in places, although access is difficult because of the swampy ground.