WAEC SSCE - Geography - 2009 (Essay)

(a) Soil profile

A soil profile is a vertical section of soil from the ground surface down to the parent rock or bedrock, showing the different layers or horizons of the soil.

(b) Well-labelled diagram of a soil profile

(c) Characteristics of the three zones of a soil profile

1. A horizon (topsoil or zone of eluviation)
   • It is the uppermost layer of mineral soil, immediately below the surface litter.
   • It contains decaying plant and animal remains which form humus.
   • It is dark in colour and is usually the most fertile horizon.
   • It is the zone of greatest biological activity, containing many soil organisms and most plant roots.
   • Soluble minerals and fine materials are washed down from this horizon by percolating water.
2. B horizon (subsoil or zone of illuviation)
   • It lies below the A horizon and contains little humus.
   • It is the zone in which clay, iron, aluminium and other mineral materials leached from the A horizon accumulate.
   • It is often reddish, brownish or yellowish because of iron compounds.
   • It is usually denser and more compact than the topsoil.
   • Only deep-rooted plants commonly extend into this horizon.
3. C horizon (parent-material horizon)
   • It consists mainly of partly weathered rock fragments and other parent material from which the soil develops.
   • It contains very little or no humus and has little biological activity.
   • It is coarser and less developed than the A and B horizons.
   • It grades downward into hard, unweathered bedrock.

(a) Sketch map of Africa

Key locations: River Nile is in north-eastern Africa and flows northwards to the Mediterranean Sea. River Limpopo is in south-eastern Africa and flows eastwards to the Indian Ocean. Lake Victoria is in East Africa near the Equator, while Lake Chad is in the north-central interior. The Namib Desert lies along the south-western coast, and the Kalahari Desert lies in the interior of southern Africa.

(b) Uses of rivers and lakes in Africa

1. They provide water for domestic purposes such as drinking, cooking and washing.
2. They provide water for irrigation and support livestock farming.
3. They provide fish and employment in fishing, fish processing and boat building.
4. They are used for inland water transport of people and goods.
5. They are dammed for the generation of hydro-electric power.
6. They supply water for industries and serve as tourist and recreational centres.

(c) Factors limiting the use of rivers and lakes in Africa

1. Rapids and waterfalls interrupt river courses and hinder navigation.
2. Seasonal fluctuations in water level cause some rivers to become shallow or dry up in the dry season, while flooding occurs in the wet season.
3. Silting and sand bars, especially at river mouths, obstruct navigation.
4. Aquatic weeds, such as water hyacinth, block waterways and hinder fishing and transport.
5. Many rivers pass through sparsely populated, desert or otherwise unproductive areas, reducing their economic usefulness.
6. Some rivers cross international boundaries, creating problems of joint control, development and use.

(a) Outline map reduced to a scale of 1:150,000

The reduction factor is:

\[\frac{1:150\,000}{1:50\,000}=3\]

Thus, every length on the original extract is reduced to one-third. The completed reduced outline is shown below.

(b) Features marked on the outline

1. Nodal settlement: Kaiama. Several roads converge at Kaiama.
2. Secondary road: No secondary road is shown on the map extract. The roads shown are the main road and minor roads or tracks.
3. Trigonometrical station: the trigonometrical station northwest of Kaiama, marked by the trigonometrical-station symbol.

(c) Full length of River Gbesha from point X

Length measured along the winding river course on the map = \(27.4\text{ cm}\).

At a scale of \(1:50,000\):

\[\text{Ground distance}=27.4\times50,000=1,370,000\text{ cm}\]

\[\text{Ground distance}=\frac{1,370,000}{100,000}=13.7\text{ km}\]

Therefore, the full length of River Gbesha from X is 13.7 km.

(d) Identification

(i) Land-use types

1. Agriculture or farming, indicated by scattered cultivation.
2. Animal grazing, indicated by the savanna vegetation.

Other identifiable land uses include settlement and transportation.

(ii) Social amenities in Kaiama

1. Postal agency
2. Market
3. Health centre

Other social amenities shown include a rest house, church and school.

(a) Outline map of West Africa

The map shows:

• Area of dense population: south-western Nigeria (Yorubaland/Lagos area).
• Important town in the dense area: Lagos.
• Area of sparse population: northern Niger, within the Sahara Desert region.
• Important town in the sparse area: Agadez.
• River Niger: from the Guinea Highlands, through Mali and Niger, then south through Nigeria to the Gulf of Guinea.

(b) Factors responsible for the high population density in south-western Nigeria

1. Favourable climate: The area has reliable rainfall, warm temperatures and a relatively humid environment, which favour settlement and agricultural production.
2. Fertile soils and agriculture: Fertile soils support food crops and cash crops such as cocoa, kola nut, oil palm and vegetables. Intensive farming can therefore sustain a large population.
3. Industrialisation and employment: Lagos and other towns contain factories, offices, markets, banks and transport businesses. These provide employment and attract migrants from other areas.
4. Port and commercial functions: Lagos is a major coastal port and commercial centre. Import, export, shipping and trading activities encourage the concentration of people.
5. Social amenities and transport: Good road and rail links, schools, hospitals, electricity, water supply and other services make the area attractive for settlement.
6. Historical and administrative importance: The area has long been occupied and urbanised, while Lagos developed as an important colonial and administrative centre. This has encouraged continuous population growth.

(c) Problems of sparse population density

1. Shortage of labour: There are too few workers to cultivate land fully, exploit mineral resources and undertake major development projects.
2. High cost of providing services: Scattered settlements make roads, schools, hospitals, water supply and electricity expensive to provide; the small population also creates a limited market for goods and services.

(a) Divergence line graph

The monthly temperatures and their departures from the annual mean are:

Annual mean temperature:

\[\bar T=\frac{10+14+22+32+42+48+44+38+32+24+16+10}{12}=\frac{332}{12}=27.7^\circ\text{C}\]

The bold horizontal line on the graph represents the mean temperature, or zero departure. Temperatures above it are positive departures and those below it are negative departures.

(b)(i) Annual range of temperature

\[\text{Annual range}=\text{temperature of hottest month}-\text{temperature of coldest month}\]

\[=48^\circ\text{C}-10^\circ\text{C}=\boxed{38^\circ\text{C}}\]

(b)(ii) One other method of showing the statistics is a simple bar graph.

(a) (i) Main lines of latitude

Lines of latitude are imaginary parallel circles drawn round the Earth and measured north or south of the Equator.

The main lines of latitude are:

• Arctic Circle, \(66\tfrac{1}{2}^{\circ}\text{N}\)
• Tropic of Cancer, \(23\tfrac{1}{2}^{\circ}\text{N}\)
• Equator, \(0^{\circ}\)
• Tropic of Capricorn, \(23\tfrac{1}{2}^{\circ}\text{S}\)
• Antarctic Circle, \(66\tfrac{1}{2}^{\circ}\text{S}\)

(a) (ii) Distance between Addis Ababa and Maseru

Latitude of Addis Ababa = \(10^{\circ}\text{N}\)

Latitude of Maseru = \(30^{\circ}\text{S}\)

Since the two towns are on opposite sides of the Equator:

\[\text{Difference in latitude}=10^{\circ}+30^{\circ}=40^{\circ}\]

\[1^{\circ}\text{ of latitude}=111\text{ km}\]

\[\text{Distance}=40\times111=4,440\text{ km}\]

Therefore, the distance between Addis Ababa and Maseru is \(4,440\text{ km}\).

(b) (i) Revolution of the Earth

Revolution is the movement of the Earth round the Sun in its orbit. The Earth completes one revolution in about \(365\tfrac{1}{4}\) days.

(b) (ii) Effects of revolution on the length of day and night in the Northern Hemisphere

• The Earth’s axis is tilted, and it remains inclined in the same direction as the Earth revolves round the Sun. Consequently, the length of day and night changes during the year.
• About 21 June, the Northern Hemisphere is tilted towards the Sun. It experiences summer, with longer days and shorter nights. At the Arctic Circle there is 24 hours of daylight, and areas north of it experience the midnight sun.
• About 22 December, the Northern Hemisphere is tilted away from the Sun. It experiences winter, with shorter days and longer nights. At the Arctic Circle there is 24 hours of darkness, while areas farther north may not see the Sun.
• About 21 March and 23 September, the Sun is overhead at the Equator. These are equinoxes, when day and night are approximately equal, each lasting 12 hours.

(a) Sketch map of Nigeria showing cattle rearing and movement to markets

Key: The shaded northern savanna belt is the cattle-rearing zone. Kano is a town within the zone. The arrows show cattle moving southwards from Kano/the northern producing area to the major consuming markets of Lagos and Ibadan.

(b) Factors favouring cattle rearing in northern Nigeria

1. The extensive Sudan and Sahel savanna grasslands provide abundant natural pasture for grazing cattle.
2. The relatively dry climate and low humidity discourage the tsetse fly, thereby reducing trypanosomiasis.
3. The broad, gently undulating plains provide wide open land for grazing and movement of herds.

(c) Problems of cattle rearing in northern Nigeria

1. Rainfall is scanty and unreliable; consequently, pasture and surface water become inadequate during the long dry season.
2. Overgrazing may destroy available pasture and lead to soil erosion and desertification.
3. Diseases such as rinderpest and foot-and-mouth disease, together with inadequate veterinary drugs, vaccines and services, reduce cattle production.

(a) Outline map of Nigeria: soil zones, crops and towns

The map below shows three major soil zones and their associated crops. Kano and Ibadan are the two towns located in the northern sandy-soil zone and the southern forest-soil zone respectively.

(b) Characteristic features of two soil zones

1. Northern zone of sandy soils

• It occurs mainly in the far northern part of Nigeria, where the climate is arid or semi-arid.
• It is formed under low rainfall and sparse vegetation.
• The soil is loose, friable and porous, with coarse sand grains and a sandy-loam texture.
• It is easy to cultivate and is generally well drained.
• It contains little humus and has low water-holding capacity, so it dries out rapidly.
• It is not heavily leached because rainfall is relatively low.
• It supports crops such as groundnut, millet, cotton and maize, especially where moisture is adequate.

2. Interior zone of lateritic soils

• It is widespread in the interior and Middle Belt of Nigeria.
• It develops under alternating wet and dry tropical conditions and is commonly reddish or brownish in colour.
• Its red colour results from iron compounds; it also contains aluminium compounds.
• It is heavily leached by rainfall and is therefore generally of medium fertility unless manure or fertiliser is added.
• It is sticky when wet but hard and compact when dry, and may become relatively impervious.
• It supports food crops such as yam, cassava, cocoyam and maize.

(a) Outline map of Nigeria showing annual rainfall distribution

Key: Annual rainfall generally decreases from the southern coast northwards. The Niger Delta and coastal belt receive over 2,000 mm; the southern interior receives 1,500 to 2,000 mm; the Middle Belt receives 1,000 to 1,500 mm; while the extreme north receives about 500 to 1,000 mm annually.

(b) Effects of rainfall on the distribution of vegetation in Nigeria

1. Heavy and almost continuous rainfall, especially over 2,000 mm in the south, supports dense tropical rain forest with tall trees. In the coastal swampy areas, it also supports mangrove vegetation.
2. Moderate rainfall of about 1,000 to 1,500 mm in the Middle Belt supports Guinea Savanna, made up of tall grasses and scattered trees.
3. Low and seasonal rainfall in the north supports Sudan and Sahel Savanna, where vegetation consists mainly of short grasses, thorny shrubs and widely spaced drought-resistant trees. Thus, vegetation becomes shorter, less dense and more open from south to north as rainfall decreases.

(c) Characteristics of the Guinea Savanna

1. It has tall grasses, often growing up to about 3 m high. The grasses are green in the rainy season and dry or brown in the dry season.
2. It has few scattered trees, with open grassland between them.
3. Many of the trees are deciduous and shed their leaves during the dry season; they commonly have thick bark and deep roots to withstand drought and bush fires.
4. Gallery forests occur along river valleys and streams where moisture is available throughout much of the year.

(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.

Rail Transport

(a) Economic importance

1. Rail transport carries bulky, heavy and low-value goods, such as minerals, timber, cement, coal and agricultural produce, cheaply over long distances.
2. It links settlements, regions, producing areas, markets, factories and ports.
3. It conveys raw materials to industries and distributes finished goods to markets.
4. It opens up previously inaccessible areas and encourages farming, mining, commerce and other economic activities.
5. It carries large numbers of passengers, labourers and, where necessary, troops.
6. It promotes national integration by linking different regions of a country.
7. It aids the movement of ideas, innovations and culture between places.
8. It provides employment for railway workers and promotes tourism.
9. It generates income and revenue through passenger fares and freight charges.
10. International rail links can promote trade and relations between neighbouring countries.

(b) Problems of rail transport

1. Railway construction is very expensive, especially where bridges, tunnels, embankments and drainage works are required.
2. There is often inadequate capital for rehabilitation, expansion and purchase of modern locomotives, coaches and spare parts.
3. Poor maintenance leads to worn-out tracks, engines and coaches, frequent breakdowns and accidents.
4. Inadequate management, poor planning and unreliable time schedules reduce efficiency and patronage.
5. Narrow-gauge and single-track lines limit train speed, capacity and frequency of service.
6. Steep gradients, rugged relief, swamps and rivers make construction and operation difficult.
7. Flooding may wash away tracks or cause derailment where drainage is poor.
8. Low technological development and shortage of skilled personnel hinder modern operation.
9. Rail transport has fixed routes and cannot provide door-to-door service.
10. It faces strong competition from road and air transport, resulting in low patronage on some routes.
11. Vandalism and theft of railway equipment may interrupt services.

(c) Solutions to the problems

1. Government and private investors should provide adequate funds, including bank loans where necessary, for railway development.
2. Tracks, bridges, locomotives and coaches should be regularly maintained and worn-out parts replaced promptly.
3. Modern locomotives, faster engines and improved passenger coaches should be provided.
4. Railway managers should improve planning, scheduling, accounting and general management.
5. Personnel should be properly trained and retrained in railway engineering, signalling, maintenance and administration.
6. Uniform and wider gauges should be adopted to improve speed, safety and capacity.
7. Single lines should be upgraded to double tracks on busy routes to allow trains to move in both directions without delay.
8. Adequate drainage, culverts and embankments should be constructed to reduce flooding and overcome difficult gradients.
9. Local manufacture or reliable supply of spare parts should be encouraged.
10. Modern communication, signalling and security systems should be installed to reduce accidents, theft and vandalism.
11. Rail services should be coordinated with road, water and air transport so that railways concentrate on heavy, bulky and long-distance traffic.