WAEC SSCE - Geography - 2005 (Essay)

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(a) Meaning of soil erosion

Soil erosion is the wearing away, loosening and removal of the top (surface) layer of the soil from one place to another by natural agents such as running water, wind, ice or waves, and often accelerated by human activities. It is most serious when the fertile topsoil is stripped away faster than it can be replaced.

(b) Notes on soil erosion

(i) Causes

• Heavy rainfall and steep slopes, which give fast-flowing run-off that carries soil away (sheet, rill and gully erosion).
• Removal of vegetation cover through deforestation, bush burning and overgrazing, leaving the soil bare and exposed.
• Poor farming methods such as ploughing up and down slopes, continuous cropping and shifting cultivation on fragile land.
• Strong winds in dry, bare areas that blow away loose soil particles.

(ii) Effects

• Loss of soil fertility as the nutrient-rich topsoil is removed, reducing crop yields.
• Formation of gullies and badlands that destroy farmland, roads and buildings.
• Silting of rivers, dams and reservoirs by the eroded material, causing flooding and shortening the life of dams.
• Desertification and migration as land becomes unproductive, forcing people to move away.

(iii) Methods of prevention

• Afforestation and re-vegetation to bind the soil with roots and break the force of rain and wind.
• Contour ploughing, terracing and strip cropping on slopes to slow down run-off.
• Cover cropping, mulching and crop rotation to keep the soil covered and maintain fertility.
• Building drainage channels, check dams and planting wind breaks (shelter belts), and controlling bush burning and overgrazing.

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(a) Meaning of error of closure

In a closed traverse the survey lines are run round an area and should end exactly at the starting point. The error of closure is the small gap or difference between the true starting point and the point at which the survey actually closes when it is plotted, that is, the amount by which the survey fails to close back onto its origin. It shows the total accumulated error of the survey.

(b) Four sources of error of closure in a closed traverse survey

• Instrumental errors: a faulty or wrongly graduated chain/tape, a badly adjusted compass or theodolite, or a bent ranging pole.
• Errors in measuring angles/bearings: wrong reading of the compass or theodolite, local magnetic attraction affecting the needle, or failing to take the back bearing.
• Errors in measuring distances: inaccurate chaining, sag or stretch in the tape, sloping ground not corrected to the horizontal, or miscounting the chains/arrows.
• Personal (human) and plotting errors: careless booking, mistakes in recording figures, and errors made when plotting the survey on paper (wrong scale, poor drawing).

(c) Two measures to avoid an error of closure

• Check and adjust the instruments before use and take readings carefully, repeating and averaging measurements of both distances and angles.
• Apply proper field checks such as measuring back bearings, using check lines/tie lines, and keeping away from sources of magnetic disturbance; any small residual error is then distributed by adjustment (for example the Bowditch rule) when plotting.

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(a) Definitions

• (i) Optimum population: the ideal population size that, with the available resources and level of technology, gives the highest standard of living (the greatest output and welfare per person). It is neither too many nor too few people for the resources.
• (ii) Over-population: a situation in which the population is too large for the available resources and technology to support at a reasonable standard of living, so that resources are over-stretched and welfare falls.
• (iii) Population density: the average number of people living on each unit area of land, usually expressed as persons per square kilometre. It is found by dividing the total population by the total land area.

(b) Population density of country Q

\[\text{Population density} = \frac{\text{Total population}}{\text{Land area}}\]

\[= \frac{4\,000\,000}{400\,000} = 10 \text{ persons per km}^2\]

Population density = 10 persons per km² (a low/sparse density).

(c) Four disadvantages of this low population density on the economy of the country

• Shortage of labour: too few people to work the farms, mines and industries, so resources remain unused or under-developed.
• Small home market: low demand for goods and services discourages large-scale production and investment.
• High cost of infrastructure per head: roads, water, electricity and other services are expensive to provide and maintain for a thinly spread population.
• Weak revenue and slow development: a small population yields little tax revenue and a small workforce, so defence, government services and the general pace of economic growth suffer.

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(a) Meaning of karst topography

Karst topography is the distinctive scenery that develops in regions of thick, well-jointed limestone (or other soluble rock such as dolomite or chalk) as a result of solution (carbonation) weathering. Rainwater, being a weak carbonic acid, dissolves the limestone along its joints and cracks, producing a landscape of underground drainage with characteristic surface and underground features. The name comes from the Karst region of the former Yugoslavia.

(b) Four features found in karst regions

• Swallow holes (sink holes / dolines).
• Limestone caves and caverns.
• Stalactites and stalagmites (in the caves).
• Limestone pavements with clints and grikes; also gorges and underground streams.

(c) Five characteristics of karst regions

• Underground drainage: surface streams disappear down swallow holes and flow underground, so the surface is often dry.
• Presence of caves and caverns formed by solution beneath the surface, decorated with stalactites (hanging from the roof) and stalagmites (rising from the floor).
• Bare, rocky surface with limestone pavements (clints separated by grikes) and thin, poor soils, so vegetation is scanty.
• Numerous joints and cracks in the well-bedded limestone along which solution takes place; enlarged joints and dolines are common.
• Deep gorges and steep-sided valleys formed where cave roofs collapse, and re-emergence of streams as springs at the foot of the limestone.

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(a) Meaning of Vulcanicity

Vulcanicity (vulcanism) is the process by which molten rock (magma), gases and other volcanic materials from the interior of the Earth are forced towards or onto the surface. It includes both intrusive activity (magma cooling within the crust to form features such as batholiths, dykes, sills and laccoliths) and extrusive activity (lava and materials reaching the surface to form volcanoes, lava plateaux and geysers).

(b) Formation and appearance of a volcanic (lava) plateau

Mode of formation: A volcanic plateau is formed by fissure eruptions. Very fluid, basic (basaltic) lava wells up quietly through long cracks or fissures in the crust rather than from a single vent. Because the lava is thin and runny, it spreads out over a wide area before cooling. Repeated eruptions build up layer upon layer of solidified lava (basalt) until a thick, extensive, raised, flat-topped upland is formed.

Appearance: It appears as a broad, high, almost level or gently undulating tableland with steep edges. It is built of horizontal sheets (layers) of basalt, and rivers later cut deep gorges and valleys into it. Examples include the Jos Plateau region basalts, the Ethiopian (Abyssinian) Plateau and the Deccan Plateau of India.

(c) Four effects of Vulcanicity

• Fertile soils: weathered volcanic (lava) materials give rich soils good for farming crops such as coffee, tea and cocoa.
• Landform and scenic value: it creates mountains, plateaux, crater lakes and hot springs that attract tourists.
• Mineral and geothermal resources: volcanic areas yield useful minerals and provide geothermal energy (steam/hot springs) that can generate electricity.
• Hazards: violent eruptions destroy life, farmland and property, and can cause earthquakes and force people to migrate.

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(a) Three characteristics of forest vegetation

• Trees dominate and grow tall, forming a closed or nearly closed canopy so that the ground receives little sunlight.
• Layered (storeyed) structure, with emergent tall trees, a main canopy layer, and lower shrub and ground layers.
• Dense and varied plant life, many species of hardwood trees mixed together, with climbers (lianas), epiphytes and, in wet forests, broad evergreen leaves; the trees often have buttress roots.

(b) Three ways vegetation is important as an environmental resource

• Protects the soil and water: it binds the soil with roots, checks erosion, and helps rainfall to soak in, keeping rivers and springs supplied.
• Regulates climate and air quality: plants take in carbon dioxide and give out oxygen, add moisture to the air, and moderate temperature, reducing the greenhouse effect.
• Habitat and raw materials: it provides a home for wildlife and supplies timber, fuel wood, medicines, fruits and grazing, which support human livelihood.

(c) Two problems from over-utilization of vegetation resources

• Deforestation leading to soil erosion and loss of fertility, flooding, silting of rivers and eventual desertification.
• Destruction of habitat and loss of biodiversity, so that wildlife and useful plant species become scarce or extinct, and the climate is disturbed.

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(a) Meaning of settlement

A settlement is any place, ranging from a single homestead to a large city, where people live and build their dwellings and carry on their activities. It is the way in which people group their houses and occupy a piece of land. Settlements may be temporary or permanent, and are broadly divided into rural (village) and urban (town/city) types.

(b) Four characteristics of an urban settlement

• Large population living at high density, so houses are close together and often storeyed.
• Non-agricultural occupations dominate: most people work in industry, commerce, services and administration rather than farming.
• Well-developed infrastructure and services: good roads, electricity, pipe-borne water, schools, hospitals, banks, markets and recreational facilities.
• Complex functions and land use with distinct residential, commercial, industrial and administrative zones, and a wide range of social groups.

(c) Four functions an urban settlement performs for a rural settlement

• Market/commercial centre: the town buys the farm produce of the villages and supplies them with manufactured goods.
• Provision of services: it offers higher-order services such as hospitals, secondary and tertiary schools, banks and administrative offices used by rural people.
• Source of employment: it absorbs surplus rural labour, providing jobs in industries and services.
• Centre for processing and distribution: it processes raw materials from the countryside and acts as a transport/collecting hub linking the villages to wider markets; it also supplies farm inputs (tools, fertiliser) and spreads new ideas and technology.

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(a) Three plantation crops in Africa

• Cocoa.
• Oil palm.
• Rubber.

(Others acceptable: coffee, tea, sugar cane, banana, sisal.)

(b) Four ways in which plantation agriculture is important

• Foreign-exchange earnings: plantation crops such as cocoa, coffee, tea and rubber are exported and bring in foreign currency.
• Employment: plantations provide large-scale jobs for many workers in growing, harvesting and processing.
• Raw materials for industry: they supply factories (for example oil palm for oil and margarine, rubber for tyres), encouraging industrial growth.
• Development of infrastructure and rural areas: roads, railways, health and housing facilities are provided, and the crops widen and diversify the economy.

(c) Three differences between plantation agriculture in West Africa and East Africa

West Africa	East Africa
Mostly lowland/coastal crops such as oil palm, cocoa and rubber.	Mostly highland crops such as tea, coffee and sisal grown on the cooler plateaux.
A large share of output comes from smallholder/peasant farmers alongside plantations.	Large European/foreign-owned estates played a bigger role in the plantation system.
Grown mainly in the hot, wet equatorial/forest lowlands.	Grown mainly on the high, cooler and well-drained volcanic uplands.

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(a) Advantages and disadvantages of water transport

Three advantages:

• Cheapest for bulky goods: ships and barges can carry very large, heavy cargoes (oil, grain, ores) over long distances at low cost per tonne.
• Natural, ready-made routes: seas, oceans, rivers and lakes provide free routeways, so little construction is needed compared with roads and railways.
• Low fuel and maintenance cost per unit carried, and it links many countries and continents, promoting international trade.

Three disadvantages:

• Very slow, so it is unsuitable for perishable goods and urgent deliveries.
• Limited routes: it can serve only places on or near navigable water, and needs feeder transport to reach inland destinations.
• Affected by weather and needs costly port facilities; storms, fog, ice and shallow water can delay or endanger vessels.

(b) Four factors that hinder the use of water transport

• Shallow water, rapids, waterfalls and sand bars that block or interrupt navigation on rivers.
• Seasonal changes in water level (low water in the dry season, floods in the wet season) that make some rivers navigable only part of the year.
• Silting of channels, ports and river mouths, and the growth of aquatic weeds, which obstruct vessels.
• Freezing of rivers and lakes in cold regions, and adverse weather such as storms and fog; also the high cost of dredging and building/maintaining harbours.

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(a) Longitude of Addis Ababa

The Earth turns \(360^\circ\) in 24 hours, so \(1\) hour of time = \(15^\circ\) of longitude.

Time difference between Addis Ababa (12:00 noon) and London (08:00 GMT):

\[12:00 - 08:00 = 4 \text{ hours}\]

Longitude difference:

\[4 \times 15^\circ = 60^\circ\]

Because Addis Ababa is ahead of GMT (its clock reads later than London's), it lies east of the Greenwich Meridian.

Addis Ababa is on longitude \(60^\circ E\).

(b) Explanatory notes

(i) Time zones: A time zone is a belt of the Earth's surface, about \(15^\circ\) of longitude wide, that keeps the same clock time. The world is divided into 24 such zones (each 1 hour apart) so that places within a zone use one convenient standard time instead of a slightly different local time at every meridian.

(ii) Standard time: This is the single, uniform clock time adopted by a whole country or zone, usually based on a chosen central meridian. It saves the confusion of many local times; large countries that stretch across several meridians (such as the USA or Russia) adopt more than one standard time.

(iii) International Date Line: This is the imaginary line drawn mainly along the \(180^\circ\) meridian in the Pacific Ocean where the date changes. A traveller crossing it going westward (eastern to western hemisphere) gains a day (moves the calendar forward), while going eastward loses a day. The line is bent in places to avoid splitting land areas and island groups into two different dates.

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(a) Printing the letters on the map

• Conical Peak (CP): print in the north-east, on the hill whose contour rings are roughly circular and close together, tapering to a single high point (the ground above 750 ft).
• Narrow River Valley (NRV): print in the south-west, where the contours form a sharp V enclosing a stream.
• Even Slope (ES): print in the eastern part, where the contours are equally spaced, showing a uniform gradient.

(b) Gradient of the minor road from the Sabongidda junction to the church in Aviosi

Height at the Sabongidda road junction \(=250\text{ ft}\); height at the church in Aviosi \(=675\text{ ft}\).

\[\text{Vertical interval}=675-250=425\text{ ft}.\]

Road distance measured on the map \(=5.9\text{ in}\). Since \(1\text{ mile}=5280\text{ ft}\) and the scale is 1:50,000 (1.25 in to 1 mile):

\[\text{Horizontal equivalent}=\frac{5.9}{1.25}=4.7\text{ miles}=4.7\times5280=24\,816\text{ ft}.\]\[\text{Gradient}=\frac{\text{Vertical interval}}{\text{Horizontal equivalent}}=\frac{425}{24\,816}=\frac{1}{58}.\]

The gradient of the minor road is 1 in 58 (1:58).

(c) Location and functions of Uhomora

Location: Uhomora lies in the south-east of the map, on the spur between two tributaries of River Onwan, on level ground between the 250 ft and 300 ft contours.

Functions:

• It is a nodal town, being the meeting point of two minor roads.
• It performs a medical function, shown by the hospital and dispensary.
• It performs an educational function, shown by the schools.
• It performs a religious function, shown by the churches.

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(a) Four factors that determine the temperature of a place

• Latitude: places near the Equator receive the Sun's rays more directly and are hotter than places near the poles where the rays are slanting.
• Altitude: temperature falls with height (about \(6.5^\circ C\) per 1000 m), so highlands are cooler than lowlands on the same latitude.
• Distance from the sea (continentality): coastal places have milder, more even temperatures because the sea heats and cools slowly, while inland places have hotter days and colder nights.
• Ocean currents and prevailing winds: warm currents/winds raise temperature and cold currents/winds lower it (also acceptable: cloud cover, nature of the surface/vegetation, and aspect).

(b) Koppen's climatic classification

(i) The two climatic elements used as the basis:

• Temperature and Precipitation (rainfall).

(Koppen combined these with the natural vegetation of each region.)

(ii) The main climatic groups in Koppen's classification:

• A - Tropical (hot, wet) climates.
• B - Dry (arid and semi-arid/desert and steppe) climates.
• C - Warm temperate (mild, mid-latitude) climates.
• D - Cold temperate (cold, snowy, mid-latitude/continental) climates.
• E - Polar (cold, ice and tundra) climates.

(Some versions add H - Highland/mountain climates.)