WAEC SSCE - Geography - 2007 (Essay)

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Hot Desert Climate

(a) Location

Hot deserts are mainly found between about 15° and 30° north and south of the Equator, especially on the western sides of continents and in continental interiors. They occur in the belt of subtropical high pressure where dry, descending air prevents cloud formation and rainfall.

Examples include the Sahara in North Africa, Arabian Desert, Thar Desert, Namib and Kalahari deserts in southern Africa, Atacama Desert in South America, deserts of south-western USA, and the Great Australian Desert.

(b) Characteristic features

The climatic graph below shows the very low rainfall and persistently high temperature of a hot desert climate.

Monthly climatic data represented in the graph

Month	J	F	M	A	M	J	J	A	S	O	N	D
Temperature (°C)	17	20	25	30	34	38	40	39	35	29	22	18
Rainfall (mm)	3	2	2	1	0	0	1	2	4	5	3	2

• Temperatures are high throughout the year. Day temperatures may exceed 38°C and may rise to about 50°C in some deserts.
• There is a large diurnal range of temperature: days are intensely hot, while nights may be cold because clear skies permit rapid loss of heat by radiation.
• Rainfall is very low, unreliable and usually below 250 mm annually. In the graph, the annual total is only 25 mm.
• When rain falls, it is often convectional, sudden and violent, producing flash floods in dry valleys.
• Skies are generally clear, sunshine and solar radiation are intense, and evaporation is high.
• Relative humidity is low, often about 30% or less.
• Dry descending air of the subtropical high-pressure belt produces arid conditions. Cold currents, such as the Canary and Benguela currents, intensify aridity along some west coasts.
• Dust storms and sand storms are common. Soils are mainly sandy, stony or rocky and have little humus.

(c) Vegetation

• Vegetation is sparse, scattered and widely spaced because of inadequate moisture.
• The plants are mainly xerophytes, that is, plants adapted to drought. Common examples are cactus, acacia, thorny shrubs, grasses and herbs.
• Plants often have long tap roots or widespread shallow roots to obtain scarce water.
• Some have thick, fleshy or succulent stems for storing water.
• Leaves are small, waxy, leathery, hairy, needle-like, or reduced to spines or thorns, thereby reducing transpiration.
• Date palms occur around oases where underground water is available. Some plants are salt-tolerant halophytes.
• Annual grasses and herbs grow rapidly after short periods of rain, flower, produce seeds and die before the next dry period.

(d) Human activities

• Nomadic pastoralism: camels, goats and sheep are reared as herders move in search of water and pasture.
• Oasis and irrigated farming: dates, vegetables, wheat, millet, sorghum and other crops are grown where river water, wells or underground water is available.
• Mining and petroleum production: oil, natural gas, phosphates, salt and other minerals are extracted in many desert areas.
• Trading and transport: caravan routes and modern roads link settlements and move goods across deserts.
• Tourism and energy generation: desert scenery attracts tourists, while the abundant sunshine favours solar-energy projects.

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(a) Sketch map of Africa

Key locations: River Niger in West Africa; River Zambezi in south-central Africa; Lake Victoria in East Africa; the Tropic of Cancer at 23½°N; the Tropic of Capricorn at 23½°S; the Atlas Mountains in north-west Africa; the Niger Delta petroleum field in Nigeria; and the Witwatersrand goldfield in South Africa.

(b) Economic importance of petroleum in the Niger Delta, Nigeria

1. Petroleum earns substantial foreign exchange through the export of crude oil and petroleum products.
2. It provides revenue to the government through taxes, royalties, rents and export duties.
3. It creates employment for geologists, engineers, refinery workers, tanker drivers, construction workers and many other workers.
4. It supplies energy and fuel for transport, industries, electricity generation and households.
5. It provides raw materials for petrochemical industries, including the manufacture of plastics, fertilisers, lubricants, bitumen and synthetic fibres.
6. It promotes the development of related industries such as oil refineries, petrochemical plants, liquefied natural gas plants and servicing companies.
7. It has encouraged the provision of infrastructure such as roads, ports, pipelines, airports, electricity and water supply in oil-producing areas.
8. It attracts foreign capital, technical skills and technology into the area.

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(a)(i) Definition of Environmental Resources

Environmental resources are the natural materials and features of the environment that are of value and can be used by man to satisfy his needs, either directly or after processing. They include living (biotic) and non-living (abiotic) components supplied by nature.

(a)(ii) Two types of environmental resources other than water:

• Mineral resources (e.g. petroleum, coal, iron ore, gold, limestone).
• Vegetation/forest resources (e.g. timber, medicinal plants). (Also acceptable: soil, wildlife, air, solar energy.)

(b) Four ways water is important as an environmental resource:

• Domestic use for drinking, cooking, washing and general household needs.
• Agriculture for irrigation of crops and for watering livestock.
• Industry and power: water is used for cooling, processing and to generate hydro-electric power.
• Transport, fishing and trade: rivers, lakes and seas provide navigable routes and support fisheries. (Also: recreation and tourism.)

(c) Two problems arising from degradation of water resources:

• Water-borne diseases and health hazards: polluted water spreads cholera, typhoid and dysentery, raising death and sickness rates.
• Scarcity of clean water and loss of aquatic life: pollution and drying up reduce supply for domestic, farm and industrial use and destroy fish and other organisms, threatening livelihoods.

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(a) Sketch map of Nigeria

Key locations shown on the map:

1. Adamawa Highlands in the North-East.
2. Yoruba Highlands in the West.
3. River Benue, associated with the Adamawa highland region, and River Ogun, rising in the western uplands.
4. Kainji Lake, a man-made lake on the River Niger.
5. Lake Chad in the extreme North-East.

(b) Importance of the highlands of Nigeria

1. They are sources of minerals. The Jos Plateau, for example, has deposits of tin and columbite, while granite and other building stones are obtained from highland areas.
2. They are sources of rivers and water supply. Many rivers rise from highland areas. These rivers provide water for homes, livestock and irrigation and may be used for fishing and other economic activities.
3. They provide sites for hydro-electric power generation. Rivers flowing down steep highland slopes form rapids and waterfalls. These provide suitable conditions for generating hydro-electric power.
4. They attract tourists and support recreation. Their scenic relief, waterfalls, cool climate and natural vegetation make highland areas important tourist centres.
5. They have a cool climate favourable for settlement and specialised farming. Highlands are cooler than surrounding lowlands and support crops such as potatoes, vegetables, tea and apples, especially on the Mambilla Plateau.
6. They provide grazing land for transhumance. During the dry season, pastoralists move cattle to the cooler, better-watered highlands where pasture is available.

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(a) Marking and naming the features on the map

• Spur (SP): a tongue of high land projecting from a hillside, shown by contours forming a V or U that points DOWN the slope, towards lower values. Mark its nose with the letters SP.
• Gentle slope (GS): an area where the contour lines are widely spaced, showing a small rise over a large horizontal distance. Mark it GS.
• Watershed (WS): the crest of high land separating two drainage basins, so that streams flow away from it in opposite directions. Mark it WS.
• V-shaped valley (VS): a young river valley where the contours form a V pointing UP the slope, with the river at the base of the V. Mark it VS.

(b)(i) Length of River Dakorobi from its source to its confluence with River Sencha

Lay a thread (or the edge of a piece of paper) along the winding river, straighten it against the scale and read the map length.

Length on map = 10.8 cm; Scale = 1:50,000, so 1 cm represents 50,000 cm = 0.5 km.

(b)(ii) Relief of the mapped area

• The area is generally a highland, with heights ranging from about 950 ft to over 3000 ft.
• It is lowest in the north-east and highest in the north-west.
• The north-west is rugged, with steep slopes, V-shaped valleys and cliffs.
• Pockets of isolated hills run from the north-west to the south-east.
• The south-west and north-east have gentle, rolling slopes.

(c) Influence of relief on settlement

• The high relief gives the area a generally dispersed settlement pattern.
• Most settlements are found on the gentle slopes to the south of the map, where building and farming are easier.
• The rugged, mountainous north-west attracts few settlements; the only ones there are Mayo, Dongi and Kenchungu.
• Settlements avoid the steep slopes, while passes attract settlement, for example Karlahi.

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(a) Outline map of Nigeria showing three vegetation belts and one town in each belt

The map shows three valid vegetation belts arranged broadly from the wetter south to the drier north. Tropical rainforest occurs in the humid south; Guinea savanna occupies much of the Middle Belt; and Sudan savanna occurs farther north. Other belts, such as mangrove swamp forest along the Niger Delta and Sahel savanna in the extreme north-east, could also be shown if required.

(b) Three effects of rainfall on vegetation in Nigeria

• High rainfall in southern Nigeria produces dense, evergreen tropical forest.
• Heavy rainfall supports the growth of tall trees in the south.
• Lower rainfall towards northern Nigeria favours grasses and short, widely spaced deciduous trees rather than dense forest.

Where rainfall is very scanty in the extreme north, vegetation becomes sparse, with short scattered grasses and scrub. The key relationship is that rainfall generally decreases from south to north, so vegetation changes from forest to savanna and then to sparse scrub.

(c) Two uses of vegetation resources in Nigeria

• Forests provide timber and wood for construction, furniture and fuel.
• Vegetation provides food and raw materials, including fruits, nuts, medicinal plants, rubber and gum Arabic.

Examination reminder: For rainfall-and-vegetation questions, link the amount of rainfall to a named vegetation feature: high rainfall → tall, dense evergreen forest; low rainfall → grasses and short, scattered deciduous trees.

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(a) Relief features of the ocean floor

(b) Three characteristics of the continental shelf

1. It is the shallow, gently sloping submerged margin of a continent, extending from the coast to the shelf break.
2. It is generally less than about 200 m deep and is a continuation of the coastal plain beneath the sea.
3. Its width varies considerably, and its shallow water permits sunlight penetration; it is therefore rich in plankton and marine life.

(c) Importance of the continental shelf to man

1. It provides some of the world’s richest fishing grounds because plankton and fish thrive in its shallow, sunlit waters.
2. It contains valuable mineral resources, especially petroleum and natural gas, which are extracted by offshore drilling.
3. Its sheltered shallow waters provide suitable places for anchorage, ports, recreational activities and tourism.

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(a) Characteristics of sedimentary rocks:

• They are formed in layers (strata/beds) which are usually visible as bedding planes.
• They are non-crystalline and generally softer than igneous rocks.
• They frequently contain fossils of plants and animals buried during their formation.
• They are made of compacted and cemented sediments (particles of pre-existing rocks or organic matter), and are often porous and permeable.
• They are stratified and can be split along the layers.

(b) Two ways sedimentary rocks can be formed:

• Mechanically (clastic/detrital formation): rocks are weathered and eroded into fragments; these sediments are transported by water, wind or ice, deposited in layers, then compacted and cemented over time into rock such as sandstone and shale.
• Organically (biological formation): the remains of living things accumulate and are compacted, e.g. the shells and skeletons of sea organisms forming limestone/chalk, or plant remains forming coal. (Chemically formed sedimentary rocks, e.g. rock salt from evaporation, are also acceptable.)

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(a) Outline map of Nigeria showing crop-producing areas and towns

(b) Physical conditions necessary for cocoa production

1. Temperature: Cocoa requires a uniformly high temperature of about 27°C, with a low annual temperature range and no frost.
2. Rainfall: It requires moderate to heavy rainfall of about 125 to 200 cm annually, fairly well distributed through the growing season.
3. Soil and relief: It grows best on deep, fertile, humus-rich and well-drained loamy soil, usually on gently undulating land.
4. Shade and dry period: Young cocoa seedlings need shade. A short dry season, especially from December to February, assists the drying of harvested beans.

(c) Importance of cash crops to the economy of Nigeria

1. Foreign exchange and revenue: Export crops such as cocoa earn foreign exchange for Nigeria and provide revenue to government through taxes and export duties.
2. Employment and income: They provide employment and income for farmers, farm labourers, produce buyers, transporters and traders.
3. Raw materials: They supply raw materials to industries, for example cocoa to beverage and confectionery industries, cotton to textile industries and rubber to tyre industries.
4. Development of settlements: Cash-crop production promotes roads, markets, processing centres and the growth of towns in producing areas.

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(a) Three conditions that favour fruit farming in the Mediterranean Regions of Africa:

• Suitable Mediterranean climate: hot, dry, sunny summers ripen the fruit while the mild, wet winters supply moisture, ideal for citrus, grapes, olives and figs.
• Fertile, well-drained soils: the rich soils of the coastal lowlands and river valleys support healthy fruit trees.
• Availability of irrigation water and gentle relief: rivers and irrigation supply water in the dry summer, and the level to gently sloping land is easy to cultivate. (Long hours of sunshine and skilled labour are also acceptable.)

(b) Four problems facing fruit farming in the Mediterranean Regions of Africa:

• Summer drought and shortage of water, making irrigation necessary and costly.
• Pests and diseases that attack the trees and fruit, reducing yield and quality.
• Occasional hazards such as hot, dry winds (sirocco), frost or hail that damage crops.
• Marketing problems: the fruit is perishable, and there is competition, price fluctuation and the cost of storage and transport to distant markets.

(c) Three ways fruit farming is of economic importance to the Mediterranean Regions:

• Foreign exchange earned from exporting citrus, grapes, olives and wine.
• Employment and income for farmers, pickers, processors and traders.
• Raw materials for industry (wine-making, canning, olive oil and juice), which promotes agro-industrial and general economic development.

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(a) Four differences between Tropical Grassland and Temperate Grassland:

(Also acceptable: savanna supports big game/wildlife, steppe is a major zone for wheat and cattle/sheep ranching.)

(b) Climate of the Tropical Grassland (Savanna):

• High temperatures throughout the year, averaging about \(24^{\circ}\text{C}\), with the hottest period just before the rains.
• Distinct wet and dry seasons: the wet season comes with the overhead sun, the dry season when the sun is overhead in the opposite hemisphere.
• Moderate rainfall, about \(500\text{ to }1000\text{ mm}\) a year, brought by convectional storms in the wet season.
• A relatively small annual temperature range but a marked contrast between the rainy and dry periods; skies are cloudy in the wet season and clear and dusty (harmattan) in the dry season.

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(a) What is a plateau?

A plateau is an extensive area of elevated, fairly level or gently undulating highland that stands above the surrounding land and usually has at least one steep side. It is also called a tableland.

(b) Mode of formation:

(i) Tectonic plateau: Formed by earth movements (crustal forces). A large block of the earth's crust is uplifted more or less evenly by vertical forces, or is left standing between two faults (a raised block), so that a broad surface is raised to a high level without much folding. Some are formed by outpourings of lava (basalt) that build up flat-topped lava plateaux.

(ii) Dissected plateau: Formed when an existing plateau is deeply eroded by rivers and other agents. Streams cut deep valleys and gorges into the raised surface, breaking it into a rugged mass of ridges, hills and valleys. What remains of the original level surface is seen only in the accordant hill tops.

(c) Three ways plateaux are important to man:

• Mining: many plateaux are rich in minerals (e.g. tin and coal on the Jos Plateau), supporting the mining industry.
• Hydro-electric power: rivers descending the plateau edge provide waterfalls and rapids used to generate HEP.
• Settlement, farming and grazing: the cooler, healthier climate of high plateaux favours settlement, arable farming and livestock rearing, and can attract tourism.

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(a) Four factors that favour the location of a brewery industry:

• Abundant supply of clean water: brewing uses large volumes of water, so breweries are sited where good quality water is plentiful.
• Nearness to raw materials: ready supply of barley/sorghum, hops, sugar and yeast reduces transport costs.
• Large market/high population: breweries locate near towns and cities where there is a big demand for the drink, since the product is bulky and perishable.
• Availability of power, labour and good transport: a steady energy supply, skilled and unskilled workers, and good roads/rail to distribute the finished product all attract the industry. (Capital and availability of bottles/containers are also acceptable.)

(b) Three contributions of manufacturing industries to economic development of Tropical Africa:

• Employment: they create many jobs, raising incomes and living standards.
• Revenue and foreign exchange: they earn money for government through taxes and provide manufactured goods for export, saving/earning foreign exchange.
• Development and diversification: they add value to local raw materials, encourage the growth of other industries and infrastructure, and reduce dependence on imports.

(c) Three problems facing manufacturing industries in Tropical Africa:

• Shortage of capital and inadequate funding for machinery and expansion.
• Inadequate power supply and poor infrastructure (erratic electricity, poor roads), which raise costs and disrupt production.
• Shortage of skilled labour and low-level technology, together with a small local market and competition from imported goods.

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(a) Four factors responsible for the sparse population of the West Coast of South Africa:

• Aridity and low rainfall: the west coast (Namib and Karoo margins) is desert to semi-desert, cooled by the cold Benguela current, giving very low, unreliable rainfall that discourages settlement.
• Poor, infertile soils: the dry, sandy and rocky desert soils cannot support arable farming, so few people can make a living from the land.
• Scarcity of surface water: the shortage of rivers and fresh water limits domestic supply, farming and industry.
• Sparse vegetation and limited economic opportunity: the thin scrub vegetation supports little grazing, and the lack of industries and job opportunities gives people little reason to settle. (Rugged, harsh terrain in places is also acceptable.)

(b) Three disadvantages of the low population density:

• Shortage of labour for developing farms, mines and industries.
• Small local market, which discourages investment and the growth of industries and services.
• Under-utilisation of resources and high cost of providing infrastructure (roads, water, electricity) to a scattered population.

(c) Three ways population can be increased:

• Provide water through boreholes, dams and irrigation schemes to support farming and settlement.
• Develop industries and create jobs, and exploit mineral and fishing resources to attract migrants.
• Improve infrastructure and social amenities (roads, housing, schools, hospitals, electricity) to make the area more attractive to settlers.

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(a) Constructing the flow map / flow chart

A flow map shows movement between places by drawing a band (arrow) along each route whose width is drawn in proportion to the quantity of traffic along that route.

Step 1: Choose a width scale. Let 1 mm of band width = 50,000 passengers. Then divide each value by 50,000 to get the band width:

Step 2: Draw the bands. On the map of Nigeria (Map B) draw a proportional-width band from Lagos to each city, each band ruled to the width above and following the direction of the route. Shade the bands, add arrowheads to show direction of movement, and provide a title and a key showing the width scale (e.g. a 1 mm band = 50,000 passengers).

(b) Two advantages of representing data with flow maps

1. They show clearly the direction and route of movement between places, so the reader sees where the traffic goes as well as how much there is.
2. The proportional band widths give an instant visual comparison of the volume of traffic along the different routes on the actual geographical map.

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(a) Four ways water transport is important in international trade:

• Carriage of bulky and heavy goods: ships can carry large quantities of bulky, low-value goods (crude oil, grains, ores, timber) cheaply over long distances between countries.
• Cheapest means over long distances: the low cost per tonne-kilometre reduces freight charges and makes internationally traded goods cheaper.
• Links continents and distant markets: oceans connect nations separated by seas, allowing trade between continents that land transport cannot reach.
• Large carrying capacity: a single vessel moves far more than road or rail, so huge volumes of imports and exports can be handled at ports.

(b) Four limitations of water transportation:

• It is slow compared with air transport, so perishable and urgent goods are delayed.
• It is restricted to coasts, navigable rivers and lakes and cannot serve inland areas directly.
• Navigation can be hindered by natural hazards such as storms, fog, ice, shallow water, rapids, waterfalls and silting.
• It requires heavy capital for building ships, ports, harbours, canals and dredging, and delays occur during loading and unloading.

(c) Solutions to any two of the problems above:

• Restriction to waterways / reaching inland areas: construct canals and dredge rivers to extend navigable routes and link water transport with road and rail (multimodal transport).
• Natural hazards / shallow water and silting: carry out regular dredging, install modern navigation aids (lighthouses, buoys, radar, GPS) and weather forecasting to guide ships safely.

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(a) Sketch map of the Nile Valley

The map must show two named farming areas and two products from each. A suitable sketch map is shown below.

Farming areas and products shown:

• Nile Delta, Egypt: cotton and rice.
• Gezira Scheme, Sudan: cotton and groundnuts.

(b) Five economic importance of the River Nile to Egypt and Sudan

1. Irrigation: Nile water is used to irrigate crops in areas that receive little rainfall, allowing farming in desert and semi-desert land.
2. Fertile alluvial soil: the river deposits silt (alluvium), which helps to maintain fertile land for agriculture.
3. Hydroelectric power: dams on the Nile generate electricity, for example the Aswan High Dam in Egypt and dams such as Sennar in Sudan.
4. Water supply: it provides water for domestic use, livestock, and industrial activities.
5. Employment and tourism: the river supports fishing and attracts tourists, including visitors using Nile cruises and holiday facilities.

Examination reminder: For the map question, labels must include both the place and the products. For the importance question, give five separate economic uses rather than repeating different forms of irrigation or farming.