WAEC SSCE - Geography - 1989 (Essay)

Answer Details

Two pairs are chosen: (b) Waterfalls and Gorges and (d) Levees and Deltas. Each pair is described with three main differences and supported by a well-labelled diagram.

(b) Waterfalls and Gorges

(d) Levees and Deltas

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Industrial location is controlled by the pull of raw materials, power, market, labour, transport and government policy. Any three of the following are required.

(a) Textile mills in Kaduna

• Raw material: ready supply of cotton from the surrounding Northern savanna belt (Kaduna, Zaria, Katsina, Kano areas).
• Power: access to electricity from the national grid and nearby Kainji/Shiroro hydro-power.
• Water: the River Kaduna provides the large volumes of soft water needed for washing, dyeing and finishing cloth.
• Labour: abundant cheap labour from the densely populated North.
• Market: large local and national demand for cloth and clothing.
• Transport: the Lagos-Kano railway and trunk roads pass through Kaduna, easing movement of cotton in and cloth out.
• Government policy: deliberate siting of textile industries in the North to develop the region.

(b) Oil refinery in Warri

• Raw material: nearness to the Niger Delta crude-oil fields, so crude is piped over a short distance.
• Transport of product: coastal/creek location gives access to the sea for tanker export and coastal distribution; pipelines link it to depots.
• Water: abundant water from the delta creeks for cooling and processing.
• Land: availability of extensive, cheap swampy land for the large plant and storage tanks.
• Market: supplies petroleum products to the industrial south and beyond.
• Government policy: federal decision to refine crude locally rather than export it all.

(c) Pulp and paper mill in Oku Iboku

• Raw material: location within the rain-forest belt of the Cross River basin supplies timber and fast-growing gmelina plantations for wood pulp.
• Water: the Cross River provides the very large volumes of water pulping and paper-making require, and a means of moving logs.
• Power: supply of electricity from the grid.
• Transport: river and road links for bringing in wood and taking out paper.
• Market: national demand for paper and packaging materials.
• Government policy: siting an import-substitution paper industry to save foreign exchange.

(d) Cement factory in Ewekoro

• Raw material: the factory sits directly on massive limestone deposits, the chief raw material for cement; clay and shale are also locally available.
• Market: nearness to Lagos, Ibadan and Abeokuta, a large and growing construction market.
• Transport: good road and rail links to the coastal cities for distributing the bulky, heavy product.
• Power and labour: grid electricity and available labour from the densely settled south-west.
• Land: availability of land for quarrying and the plant.

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(a) Sketch map of Africa showing the named dams

The outline of the continent is drawn and each dam is marked with a solid dot (●) at its correct position on the river named, then labelled:

• Aswan Dam – on the River Nile in southern Egypt (north-east Africa).
• Owen Falls Dam – on the River Nile where it leaves Lake Victoria, at Jinja in Uganda (East Africa).
• Akosombo Dam – on the River Volta in Ghana (West Africa).
• Kariba Dam – on the River Zambezi, on the Zambia–Zimbabwe border (south-central Africa).
• Cabora Bassa Dam – on the River Zambezi in Mozambique (southern Africa).

(b) Importance of hydro-electric power (HEP) projects to the economy

With reference to specific African examples:

• Provision of electricity for industry: cheap, reliable power drives manufacturing, e.g. the Akosombo Dam on the Volta supplies the VALCO aluminium smelter at Tema in Ghana, so bauxite can be refined locally.
• Domestic and urban power supply: HEP lights homes, offices, schools and hospitals, raising the standard of living, e.g. Owen Falls (Nalubaale) supplies much of Uganda and exports power to Kenya.
• Irrigation and water supply: the reservoirs store water for farmland, e.g. Lake Nasser behind the Aswan High Dam irrigates the Nile valley and permits double-cropping.
• Flood control: the dams regulate river flow and reduce destructive downstream flooding, e.g. Aswan on the Nile and Cabora Bassa on the Zambezi.
• Fishing: the large artificial lakes support commercial fisheries, e.g. Lake Volta and Lake Kariba, providing food and income.
• Tourism and recreation: the lakes and dam walls attract visitors, generating revenue, e.g. Lake Kariba resorts.
• Water transport (navigation): the calm reservoirs serve as inland waterways, e.g. boat services on Lake Volta linking northern and southern Ghana.
• Employment and revenue: construction and operation create jobs and the sale of power earns government revenue.

(c) Problems facing the development of HEP projects in Tropical Africa

• High cost of construction: dams need enormous capital that poor countries lack, forcing reliance on foreign loans and aid.
• Seasonal variation in river flow / water shortage: reduced discharge in the long dry season lowers the water level and disrupts power output.
• Silting of reservoirs: sediment carried by rivers fills the reservoir, reducing storage capacity and shortening the dam’s life.
• High cost of resettlement: flooding large areas displaces people (e.g. over 80,000 resettled for Lake Volta), which is costly and socially disruptive.
• Shortage of skilled labour and technical expertise for building, running and maintaining the plant.
• Mechanical failure and poor maintenance of turbines and equipment interrupt supply.
• Low or scattered demand: a small, dispersed population makes projects uneconomic and long transmission lines expensive.
• Water-borne diseases: the still reservoir water breeds bilharzia (schistosomiasis) and mosquitoes (malaria).
• High evaporation losses from the reservoirs in the hot tropical climate reduce the volume of water available.

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(a) Problems of transportation

(i) The Niger-Benue waterway

• Seasonal fluctuation in water level: the rivers are shallow and non-navigable to large craft in the dry season, restricting use to a few months.
• Sand bars, shoals and rapids: obstacles such as rapids near Jebba and shifting sandbanks interrupt continuous navigation.
• Silting and sediment: heavy deposition reduces depth and needs constant dredging.
• Floating vegetation: water hyacinth and other weeds clog channels.
• Delta problem: a maze of distributaries and a shifting mouth make the lower course difficult to keep open.
• Poor port and handling facilities at river ports, and limited modern craft.

(ii) The Lagos-Kano railway line

• Narrow (single, narrow-gauge) track: a single line causes delays as trains must wait to pass, and the narrow gauge limits speed and load.
• Old and worn equipment: ageing locomotives, wagons and track lead to frequent breakdowns and derailments.
• Slow and infrequent service makes it uncompetitive with road transport.
• Difficult terrain: crossing rivers, the plateau and valleys required costly bridges and gradients that slow trains.
• Poor maintenance and inadequate funding of track and rolling stock.
• Vandalism and theft of rails and fittings, and inadequate feeder links to farms and towns.

(b) Possible solutions

• Regular dredging of the Niger-Benue and clearing of rapids, sandbars and floating weeds to keep channels open all year.
• Construction of dams and barrages to regulate flow and raise dry-season water levels.
• Improve river ports with modern loading, storage and navigational aids (buoys, beacons).
• Modernise the railway: re-lay to standard gauge, double the track on busy sections and replace worn track.
• Buy new locomotives and wagons and set up proper maintenance workshops.
• Provide adequate funding, tighten security against vandalism, and build feeder roads and links to widen the traffic served.

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(a) Functions of urban and rural settlements

Functions of urban settlements (towns/cities):

• Administrative - centres of government and public offices.
• Commercial and industrial - centres of trade, banking, markets and manufacturing.
• Service centres - provide higher education, specialist hospitals, transport hubs, and recreation.

Functions of rural settlements (villages):

• Agricultural production - main centres of farming, livestock keeping, fishing and forestry.
• Supply of food and raw materials to the towns.
• Source of labour and preservation of traditional/cultural life; some carry out mining or local crafts.

(b) Three areas of interdependence between rural and urban settlements

• Supply of food and raw materials vs manufactured goods: Rural areas produce food and raw materials for the town, while the town supplies the village with manufactured goods (tools, cloth, fertiliser) and processed products.
• Labour and employment: Rural areas supply workers (migrants) to urban industries and services, and towns provide jobs and wages, some of which are sent home to support rural families.
• Markets and services: The town is a market where villagers sell produce and buy goods, and it provides higher services (hospitals, schools, banks, administration) used by rural people; in turn the rural area is a market for the town's goods.

(Also acceptable: movement/transport links, and the town as a source of ideas, technology and credit for the countryside.)

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None

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The answer below describes the North Central Highlands (the Jos Plateau and its surroundings) of Nigeria under the required headings.

(a) Relief

• A high, dissected plateau standing generally between 1,200 m and over 1,800 m above sea level, rising steeply above the surrounding plains through a bounding escarpment.
• The surface is broken by isolated volcanic hills and cones, extinct crater lakes and old lava flows.
• Younger granite masses and inselbergs project above a rolling, undulating upland surface.

(b) Drainage

• The plateau is an important water tower and source region for many rivers, which radiate outward from it.
• Rivers such as the Kaduna, Gongola and headstreams draining to the Benue and to the Niger rise here.
• Streams are fast-flowing with rapids and waterfalls (for example Assop Falls) where they descend the escarpment, giving hydro-power potential.

(c) Soils

• Soils are largely derived from weathered granite and from basaltic (volcanic) material.
• Where formed on lava the soils are dark, deep and comparatively fertile; elsewhere they are shallow, gravelly and leached.
• Extensive tin-mining has disturbed and degraded soils in worked-over areas.

(d) Vegetation

• Cooler, higher rainfall on the plateau supports montane grassland with scattered short trees and shrubs.
• The lower slopes and surroundings carry Guinea savanna woodland.
• Gallery (fringing) forest lines the river valleys.

(e) Human activities

• Mining: the plateau is Nigeria's chief source of tin and columbite.
• Farming: the cool climate favours temperate crops (Irish potatoes, vegetables, wheat) and cereals such as acha, plus livestock rearing on the grasslands.
• Settlement and administration: Jos is the main urban centre.
• Tourism and health resort: the pleasant, cool climate attracts tourists and once served as a rest station.
• Power generation and dairy/ranching: streams and grasslands support hydro-power and cattle rearing.

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Reasons for the high population growth rates in developing countries

Population growth depends on the balance between the birth rate and the death rate. In developing countries the birth rate stays high while the death rate has fallen sharply, giving rapid natural increase.

• High birth rate: Fertility is high because of early marriage, limited use of family planning, and the desire for large families.
• Falling death rate through better medicine: Improved health care, immunisation, drugs and control of diseases have greatly reduced deaths, especially infant mortality, so more children survive.
• Children seen as an economic asset: On farms children provide labour and are expected to care for parents in old age, encouraging couples to have many.
• Religious and cultural beliefs: Some beliefs and traditions favour large families and discourage birth control, and a man's status may be linked to the number of his children.
• Improved food supply, water and sanitation: Better nutrition and clean water have lowered deaths from hunger and disease, raising life expectancy.
• High illiteracy and low status of women: Where education, especially of women, is low, family-planning knowledge is limited and women marry young and bear more children.
• Young age structure: Because past growth was high, a large share of the population is young and entering child-bearing age, so births remain high (population momentum).

Together these keep births high while deaths fall, producing the rapid population growth typical of developing countries.

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The relationship between climate and vegetation in Nigeria

There is a close positive relationship between climate and vegetation in Nigeria. The natural vegetation of any belt depends chiefly on the amount of rainfall it receives, the length of its rainy season and its temperature. Because rainfall is heaviest along the southern coast and decreases steadily northward, the vegetation also changes in step: it grades from dense evergreen forest in the wet south, through the savanna grasslands of the middle belt, to sparse, drought-tolerant scrub in the dry far north. As a result the vegetation belts, like the climate belts, run roughly east to west and succeed one another from south to north.

The two sketch maps below place the climate belts and the vegetation belts side by side. Notice that each vegetation belt occupies almost exactly the same position as the climate belt that produces it.

Map 1 – Climate belts

Map 2 – Vegetation belts

How the belts match, from south to north

Explaining the relationship

• Rainfall is the master control. Where rainfall is heavy and falls for most of the year (the south), trees have enough water all year, so the vegetation is a dense, multi-layered evergreen forest. Along the tidal creeks of the Delta the wettest ground carries mangrove swamp forest.
• As rainfall decreases northward, the forest thins. In the middle belt the total rainfall is lower and a real dry season appears, so tall forest gives way to Guinea savanna – a mix of tall grasses and fire-resistant trees.
• A longer, harsher dry season in the north (with the dry, dusty Harmattan) allows only grasses and scattered thorn trees to survive: this is the Sudan savanna, and in the driest north-east it becomes the open Sahel savanna of short, sparse grass and thorn scrub.
• Temperature and evaporation reinforce rainfall. The hot, dry north loses much water by evaporation, worsening the moisture shortage and favouring drought-tolerant, deep-rooted plants over tall broad-leaved trees.

Conclusion: the heavier and longer the rainfall, the thicker and taller the vegetation. Because rainfall falls steadily from the wet south to the dry north, the vegetation belts change in the same direction – from mangrove and rain forest, through Guinea and Sudan savanna, to Sahel scrub. The two sketch maps therefore show the same belts lying in the same places, proving the direct relationship between climate and vegetation in Nigeria.

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A geographical account of ECOWAS (Economic Community of West African States)

ECOWAS is a regional economic grouping of West African countries. It was established by the Treaty of Lagos on 28 May 1975 to promote economic co-operation and integration among the states of the West African sub-region. Its executive body, the ECOWAS Commission, has its headquarters in Abuja, Nigeria.

(a) Aims and objectives

• To increase and promote trade among the member countries by removing tariffs, quotas and other trade barriers, thereby working towards a common market and a common external tariff.
• To promote co-operation and development in economic activities such as industry, transport, energy, agriculture and telecommunications.
• To co-operate in social and cultural areas such as education, music and art.
• To ensure the free movement of people, goods, services and capital across member states.
• To contribute to a common fund which is used to finance joint projects and to compensate member countries that may lose economically as a result of the integration.
• To raise the standard of living of the people of the sub-region and to achieve collective self-reliance.
• To establish, eventually, a single common currency (the proposed ECO) to ease trade and payments within the region.
• To maintain peace, security and political stability in the sub-region (leading to the formation of the ECOWAS Monitoring Group, ECOMOG).

(b) Membership

ECOWAS is made up of fifteen West African member states, drawn from English-speaking, French-speaking and Portuguese-speaking countries. They are: Nigeria, Ghana, Senegal, Cote d'Ivoire, Mali, Niger, Burkina Faso, Togo, Benin, Guinea, Guinea-Bissau, Sierra Leone, Liberia, The Gambia and Cape Verde. Mauritania, a founding member, withdrew from the organisation in the year 2000. The distribution of the member states across the sub-region is shown on the sketch map below.

(c) Possible solutions to the problems of ECOWAS

• Payment of the annual financial contributions (dues) should be made compulsory, and any member that persistently refuses to pay should be sanctioned or suspended, so that the common fund is well financed.
• Proper orientation and mutual trust among members, with genuine equality in the discussion and formulation of resolutions, so that no country dominates the others.
• A neutral body should be set up to execute the programmes and projects of the organisation impartially, and common funds should be managed honestly.
• The office of the President/Chairman of ECOWAS should be rotated fairly among the Heads of State of the member countries.
• Full and speedy implementation of the protocol on the free movement of persons, goods and services, and improvement of transport and communication links (roads, railways, telecommunications) between member states to boost trade.
• Introduction of a single common currency (the ECO) to facilitate inter-regional trade and payments and to reduce dependence on the currencies of former colonial powers.
• Diversification of member economies so that they produce different, complementary goods rather than competing similar primary exports.
• Maintenance of peace and political stability through bodies such as ECOMOG, since trade and investment can only grow in a secure region.

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(a) Three major countries outside Africa that trade with Nigeria

• China, the United States of America, and India. (Others: United Kingdom, Netherlands, Germany, Japan.)

(b) Chosen country: China

(i) Three major products Nigeria exports to China:

• Crude petroleum (oil), liquefied natural gas, and agricultural products such as sesame seeds/cocoa (also solid minerals).

(ii) Three major products Nigeria imports from China:

• Machinery and equipment, electronics and vehicles, and manufactured goods such as textiles and household products.

(c) Two factors responsible for the present pattern of trade

• Difference in level of industrialisation: China is highly industrialised and produces manufactured goods cheaply, while Nigeria is less industrialised and relies on selling raw materials, so Nigeria exports primary products and imports manufactures.
• Nigeria's oil wealth and China's demand for raw materials/energy: China needs energy and raw materials for its industries, and Nigeria has abundant crude oil to sell, so oil dominates Nigeria's exports while it buys finished goods in return.

(d) Two effects of this pattern of trade on Nigeria's economy

• Unfavourable balance of trade / dependence: Nigeria often imports more (and higher-value) manufactured goods than the value it earns, and depends heavily on a single export (oil), so its economy is vulnerable to falling oil prices.
• Weak local industry and loss of jobs: Cheap imported manufactures undersell Nigerian products, discouraging local industry and reducing employment, while the sale of unprocessed raw materials means less value-addition and fewer jobs at home.

(Any listed country may be chosen; products and factors should match that country.)

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(a) Main features of rotational bush fallowing in West Africa

• The land is divided into several plots; some are cultivated while others are left fallow (resting) so that natural vegetation can regrow.
• Cultivation and fallowing rotate around the plots: after a plot has been cropped for two to three years it is abandoned, and the farmer moves to a rested plot, returning to the first after several years.
• Unlike shifting cultivation, the farmer keeps a permanent homestead and only rotates the farm plots around it.
• The fallow period allows the soil to recover its fertility naturally as vegetation returns nutrients and improves soil structure.
• Simple tools (hoe, cutlass) and family labour are used; farm sizes are small.
• Mixed cropping of food crops such as yam, cassava, maize and vegetables is common.
• Little or no chemical fertiliser is used; soil fertility is restored by the fallow and by ash from burning.

(b) Major factors affecting the practice of bush fallowing

• Population pressure: where population is high, land is scarce and fallow periods are shortened.
• Availability of land: plenty of land encourages longer fallow periods; land shortage discourages the practice.
• Soil fertility: poor tropical soils that lose fertility quickly make fallowing necessary.
• Climate and vegetation: the rate at which bush and grass regrow depends on rainfall and temperature.
• Level of technology: reliance on simple tools and lack of fertiliser makes fallowing the main way of restoring fertility.
• Land tenure system: communal land ownership allows farmers to move around and rest plots.
• Economic level and capital: subsistence farmers who cannot afford fertilisers depend on natural fallow.

(c) Problems associated with bush fallowing

• Shortened fallow periods due to population growth prevent full recovery of soil fertility, leading to declining yields.
• It requires large areas of land, which is wasteful where land is scarce.
• Low productivity means it can support only subsistence needs, not commercial farming.
• Burning of the fallow destroys soil organisms and exposes the soil to erosion.
• Scattered plots make supervision, mechanisation and provision of infrastructure difficult.
• It ties up land that could be used for permanent, more intensive agriculture.
• Continuous cropping when fallow is cut short leads to soil exhaustion and erosion.

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(a) Outline map of Nigeria

The map below shows the required rivers, lakes, highlands and lowland regions correctly located.

What is shown on the map:

• Rivers: the Niger (entering in the north-west, flowing south-east through Kainji and Jebba to the confluence at Lokoja, then south to the delta); the Benue (entering from the east and joining the Niger at Lokoja); the Sokoto (in the north-west, a tributary of the Niger); the Cross (in the south-east, draining to Calabar); and the Ogun (in the south-west, draining towards the Lagos lagoon).
• Lakes: one natural lake - Lake Chad (far north-east); and one artificial lake - Lake Kainji (the reservoir behind Kainji Dam on the River Niger).
• Highlands: the Jos Plateau (central Nigeria), the Udi Hills (near Enugu in the south-east), the Western Highlands (the Yoruba uplands of the south-west) and the Obudu Plateau (on the eastern border near Cameroon).
• Lowlands: the Sokoto Plains (a lowland region in the north) and the Niger Delta / coastal lowland (in the south).

(b) Importance of the River Niger to the economy of Nigeria

1. Generation of hydro-electric power (HEP): dams on the river at Kainji, Jebba and Shiroro generate a large part of Nigeria’s electricity, which powers homes and industries.
2. Inland water transport: the river serves as a natural waterway for moving people and goods by boat and barge, linking river ports such as Onitsha, Lokoja and Baro.
3. Irrigation: its water is used to irrigate farmlands in the dry season, supporting schemes such as the Bacita sugar and rice projects, thereby increasing food production.
4. Fishing: the river supports a thriving fishing industry that supplies protein food and income to riverine communities.
5. Employment: it provides jobs for fishermen, boat operators, dam and irrigation workers, and traders along its banks.
6. Domestic and industrial water supply: the river supplies water for household use and for factories located near it.
7. Tourism and recreation: the Kainji Lake and its National Park attract tourists, earning revenue for the country.
8. Source of building materials: sand and gravel are dredged from the river for the construction industry.

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The Tropical Monsoon climatic region

(a) Climate

• High temperatures all year (about 24-30°C), with the hottest period just before the rains break.
• A marked wet and dry season controlled by reversing monsoon winds: the on-shore south-west monsoon in summer brings very heavy rain, while the off-shore north-east winds in winter give a dry season.
• Very heavy annual rainfall (often over 2000 mm), concentrated in the summer months, sometimes with relief rainfall on windward coasts.

(b) Vegetation

• Monsoon (tropical deciduous) forest: trees shed their leaves in the dry season to reduce water loss, unlike the evergreen equatorial forest.
• Valuable hardwoods such as teak and sal, with bamboo thickets; the forest is less dense and more open than equatorial rainforest.
• Where rainfall is lower it grades into tall grassland with scattered trees.

(c) Human activities

• Intensive wet-rice cultivation on the plains and deltas, which support dense farming populations.
• Growing of other crops such as cotton, jute, sugar cane, tea and spices, and rearing of cattle.
• Lumbering of teak and other hardwoods, and processing/industries based on the farm and forest products; fishing along the coasts.

(Alternatively, the Cool Temperate Western Margin (British type) may be described: mild winters and cool summers, rain all year with a winter/autumn maximum from westerlies and depressions; natural deciduous woodland (oak, beech, ash); mixed farming, dairying, fishing, industry and dense urban settlement.)

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(a) Economic importance of rocks

• Source of building materials: Granite, limestone, sandstone and gravel are quarried for construction of houses, roads and bridges; limestone is the raw material for cement.
• Source of minerals and ores: Rocks contain valuable metallic and non-metallic minerals (iron ore, tin, gold, copper, coal, petroleum) that support mining industries and exports.
• Formation of soils for agriculture: The weathering of rocks produces the soils on which crops are grown, and some rocks (e.g. volcanic) give very fertile soils.
• Source of energy and industrial raw materials: Coal, petroleum and natural gas found in sedimentary rocks provide fuel and power; other rocks supply raw materials for glass, ceramics and chemical industries.
• Underground water and tourism/employment: Porous rocks store underground water (aquifers) tapped by wells; striking rock scenery attracts tourists, and quarrying and mining create employment and revenue.

(b) Characteristics and mode of formation of igneous rocks

Mode of formation: Igneous rocks are formed from the cooling and solidification of molten material (magma below the surface or lava on the surface).

• Intrusive (plutonic) rocks form when magma cools slowly deep underground, allowing large crystals to grow (e.g. granite).
• Extrusive (volcanic) rocks form when lava cools quickly at the surface, giving small or fine crystals (e.g. basalt).

Characteristics:

• They are crystalline, made of interlocking crystals; slow cooling gives large crystals, fast cooling gives fine ones.
• They are usually hard and non-porous, and generally lack stratification (no layers).
• They contain no fossils, because they solidified from molten material.
• They occur in masses such as batholiths, dykes and sills, and many are resistant to weathering.

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Chosen vegetation type: Tropical Rainforest (equatorial forest)

(i) Location

• Found in the low latitudes near the Equator, roughly between 5°N and 5°S.
• Chief areas: the Amazon (Congo) Basin of Central Africa, the Amazon Basin of South America, and South-East Asia (Malaysia, Indonesia); in West Africa it covers the coastal south (including southern Nigeria).

(ii) Vegetation characteristics

• Evergreen - trees keep their leaves all year because growth continues in the hot, wet climate.
• Tall trees arranged in three layers (canopy) - emergent, middle and lower storeys - with a closed canopy shutting out light.
• Great variety of hardwood species (mahogany, iroko, obeche, ebony) mixed together, not in pure stands.
• Lianas (woody climbers), epiphytes and buttress roots are common; the shaded floor has sparse undergrowth except along rivers and clearings.

(iii) Economic importance

• Timber: supplies valuable hardwoods for building, furniture, plywood and export.
• Cash crops: the climate favours cocoa, oil palm, rubber and coffee grown after clearing.
• Forest products: fuelwood, fruits, medicinal plants, rubber latex, bush meat and raffia.
• Employment, foreign exchange, and environmental value - protects soils, stores water, supports research and tourism.

(Either of the other types may be chosen instead: Laurentian - cool temperate eastern margin with mixed coniferous and deciduous forest supporting lumbering, pulp/paper and fur trapping; or Temperate grassland - prairies/steppes/pampas of tall to short grasses supporting extensive wheat farming and cattle/sheep ranching.)

Answer Details

Lumbering in Nigeria

(a) Methods of lumbering

• Selective felling: only mature and commercially valuable trees such as mahogany, iroko, obeche and opepe are cut; young trees are left to grow.
• Felling: trees are cut down with axes, cutlasses, hand-saws and, increasingly, power chain-saws.
• Trimming and cross-cutting: the felled trunk is trimmed of branches and cut into logs of manageable length.
• Log haulage: logs are dragged out of the forest by tractors, caterpillars or human/animal power to a collecting point or roadside.
• Transport to sawmills: logs are moved by lorries, or floated down rivers such as the Niger and Cross rivers, to sawmills and ports.
• Sawing and seasoning: at the sawmill logs are sawn into planks and seasoned (dried) before sale or export.

(b) Problems associated with the exploitation of timber

• Difficult accessibility: dense undergrowth, swamps and lack of roads make it hard to reach and remove timber.
• Heavy weight of logs: hardwood logs are very heavy and some do not float, raising transport costs.
• Scattered occurrence of valuable trees makes selective felling slow and costly.
• Pests and diseases attack the timber and standing trees.
• Rapid deforestation without adequate replanting depletes the forest.
• Shortage of capital and modern machinery, and of skilled labour.
• Poor transport network and bad weather (heavy rains) disrupt operations.

(c) Economic importance of lumbering in Equatorial Africa

• Foreign exchange: export of timber and wood products (e.g. from Nigeria, Zaire/DR Congo, Gabon) earns foreign currency.
• Employment: provides jobs for fellers, sawmill workers, transporters and traders.
• Raw material for industries: supplies timber for construction, furniture, plywood, paper and matches.
• Government revenue through royalties, licences and taxes.
• Development of infrastructure: roads and railways built for logging open up the interior.
• Local needs: supplies fuel-wood, building poles and materials for the local population.
• It stimulates the growth of allied industries such as furniture-making and paper-milling.

Answer Details

Factors limiting industrial development in Tropical Africa

• Shortage of capital: Most Tropical African countries are poor with low savings, so there is little money to build factories, buy machinery and provide infrastructure; they depend on scarce foreign loans and investment.
• Inadequate power supply: Industry needs steady electricity, but many areas (e.g. much of Nigeria and neighbouring states) suffer irregular power and limited energy sources, which discourages factories.
• Poor transport and infrastructure: Bad and insufficient roads, railways, ports and communications make it costly and slow to move raw materials and finished goods, raising production costs.
• Shortage of skilled labour and technical know-how: A high level of illiteracy and few trained engineers, technicians and managers mean industries must import experts, which is expensive.
• Small home market and low purchasing power: Widespread poverty means people cannot buy many manufactured goods, so the market is small and factories cannot produce on a large, cheap scale.
• Competition from imported goods: Cheaper, better-quality manufactured goods from developed countries undersell local products and stifle infant industries.
• Dependence on raw-material export / lack of local raw materials in some areas: Many economies simply export unprocessed raw materials, and some regions lack the varied raw materials needed for manufacturing.
• Political instability and weak policy: Frequent instability, poor planning and inconsistent government policy discourage long-term investment (for example, deterring investors in unstable states).

Any four, well explained with specific examples, are acceptable.

Answer Details

Irrigation agriculture in the Nile Valley (Egypt/Sudan)

(a) Methods of irrigation

• Basin irrigation: low-lying fields are enclosed by earthen banks (bunds); flood water from the annual rise of the Nile is trapped in these basins, allowed to soak the soil and deposit silt, then the surplus is drained off before planting. This is the traditional method.
• Perennial (canal) irrigation: a network of main canals, branch canals and field ditches distributes water throughout the year. Regulators and barrages (e.g. at the Aswan High Dam) store flood water and release it as needed, allowing two or three crops per year.
• Lift irrigation using traditional devices: the shaduf (a counter-weighted bucket on a pole), the sakia (an animal-turned water wheel) and the Archimedean screw (tambour) raise water from the river or canal onto higher fields.
• Modern mechanical pumps driven by diesel or electricity lift large volumes of water from the river and canals to the fields.

(b) Reasons for irrigation agriculture in the Nile Valley

• The region has a hot desert climate with very low, unreliable rainfall, so crops cannot grow on rainfall alone.
• The Nile provides a permanent, reliable supply of water flowing across the desert.
• The annual flood deposits fertile silt (alluvium), producing rich soils that support intensive cultivation.
• High temperatures and abundant sunshine throughout the year allow all-year cropping once water is supplied.
• A large, dense population needs food and cash crops such as cotton, hence the demand for continuous production.

(c) Problems associated with irrigation agriculture in the Nile Valley

• Salinisation: continuous irrigation with poor drainage causes salts to accumulate in the soil, lowering fertility.
• Waterlogging: over-watering raises the water table and floods the root zone, damaging crops.
• Loss of silt: since the Aswan High Dam traps silt in Lake Nasser, downstream fields no longer receive natural fertiliser and farmers must buy expensive chemical fertilisers.
• Spread of water-borne diseases such as bilharzia (schistosomiasis) and malaria, which breed in the standing canal water.
• Silting of canals and reservoirs reduces storage capacity and raises the cost of maintenance and dredging.
• High evaporation losses from canals and reservoirs in the hot desert climate waste water.
• Pests, weeds and disputes over water sharing between countries and farmers also occur.

Answer Details

(a) Diagram showing the four major positions of the earth during its revolution round the sun

The sun is drawn at the centre with the earth shown at four points on its orbit. Throughout the year the earth's axis stays tilted at \(23\tfrac{1}{2}^\circ\) from the vertical (that is, \(66\tfrac{1}{2}^\circ\) to the plane of the orbit) and always points in the same direction in space. The four cardinal positions are the two solstices and the two equinoxes:

• 21 June - Summer Solstice: the North Pole is tilted toward the sun, the overhead (vertical) sun is at the Tropic of Cancer (\(23\tfrac{1}{2}^\circ\)N); longest day in the Northern Hemisphere.
• 23 September - Autumnal Equinox: the axis is sideways to the sun, the overhead sun is at the Equator; day and night are equal everywhere.
• 22 December - Winter Solstice: the North Pole is tilted away from the sun, the overhead sun is at the Tropic of Capricorn (\(23\tfrac{1}{2}^\circ\)S); longest day in the Southern Hemisphere.
• 21 March - Vernal (Spring) Equinox: the axis is again sideways to the sun, the overhead sun is back at the Equator; day and night are equal everywhere.

(b) Effects of the revolution of the earth

1. Change of seasons: Because the tilted axis keeps a fixed direction, each hemisphere is inclined toward the sun for part of the year and away from it for another part, producing the succession of spring, summer, autumn and winter.
2. Varying length of day and night: Away from the Equator the days and nights change in length through the year - long days and short nights in summer, the reverse in winter - while at the Equator they remain nearly equal all year.
3. Changing altitude and apparent migration of the midday sun: The overhead noon sun appears to move to and fro between the Tropic of Cancer and the Tropic of Capricorn, so the noon sun stands higher in the sky in summer and lower in winter.
4. Occurrence of the equinoxes and solstices: The revolution fixes the four cardinal dates (21 March, 21 June, 23 September, 22 December) on which the equinoxes and solstices fall.
5. Periods of continuous day or night near the poles: Beyond the Arctic and Antarctic Circles there are spells of unbroken daylight (midnight sun) and unbroken darkness (polar night).
6. It fixes the length of the year: One complete revolution takes \(365\tfrac{1}{4}\) days; the accumulated quarter-days give an extra day (leap year) every fourth year.

Answer Details

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