- IRRIGATION (II)
- WORLD POPULATION
- WORLD POPULATION (II)
- SETTLEMENT
- ENVIRONMENTAL INTERACTION
- ENVIRONMENTAL INTERVENTION
- WORLD TRADE
- MAP WORK
- INTERPRETATION OF TOPOGRAPHICAL MAPS
Irrigation (II)
Geography, SS 3, Week 2
Topic: Irrigation (II)
Content:
Methods of irrigation
- Shaduf method involves a hand operated lever lifting buckets of water from the river and tipping or dropping them into narrow channels running along the ridges or patches of cultivation
- Perennial method involves the use of dams, barrages and canals. Water is usually stored in the dam reservoir and released during farm seasons. It promotes the growth and cultivation of crops all year round
- Basin irrigation method occurs during flooding of the rivers. When flood occurs, water is held back by building up some embankments or barriers. This water is later released during dry season
- Use of pumps involves the use of generators or pumping machines to get water out from rivers or wells to farmlands. This at times is also referred to s sprinkler irrigation
- Manual method (use of buckets) involves the fetching of water with buckets from rivers and wells and getting them to farmlands
Crops Cultivated
(a) In the Nile Basin : crops cultivated include cotton, sugar, wheat, maize and rice
(b) In the Niger Basin: crops cultivated in the Niger basin include groundnut, maize, guinea corn, onions sugar cane etc
Problems of irrigation
- The construction of dams has led to the displacement of people from their original homes and lands. This leads to high cost of resettlement
- Lack of technical know- how on the establishment and operations of irrigation scheme
- Irrigation equipments is expensive to purchase and maintain
- Excessive dissolution of salts irrigated area or increase in salinity prevents proper growths of crops
- Disaster can occur as a result of flooding
- It can result in growth of water weeds
- Most dams may collapse
ASSESSMENT
- ______ method of irrigation involves a hand operated lever lifting buckets of water from the river and tipping them into narrow channels
(a) shaduf
(b) perennial
(c) basin
(d) use of pumps - The method of irrigation that involves holding back water by building up some embankments or barriers is
(a) shaduf
(b) perennial
(c) basin
(d) use of pumps - ______ method of irrigation involves the use of generators or pumping machines to get water out from rivers or wells to farmlands
(a) shaduf
(b) perennial
(c) basin
(d) use of pumps - The method of irrigation that usually involves storing water in dams and reservoirs which is released during farm seasons is
(a) shaduf
(b) perennial
(c) basin
(d) use of pumps - One of these is not a problem associated with irrigation
(a) disaster can occur as a result of flooding
(b) It can result in growth of water weeds
(c) Most dams may collapse
(d) they are very cheap to set up
ANSWERS
- a
- c
- d
- b
- d
World Population
Geography, SS 3, Week 1
Topic: World population
Content:
- Definition
- Concepts of population
- Factors affecting the growth population
Definition of Population
Population is defined as the total number of people living in an area at a particular time.
Population Concepts
(a) Over Population: is defined as a situation whereby the population is considered too large for the availability resources. Over population refers to a situation where the population exceeds the available resources of the country
(b) Under Population is the type of population that is less than the available resources of a country. It then means that, the size of population is too small that when combined with the available resources of a country and given the level of existing technology it will secure minimum returns per head
(c) Optimum Population is the number of people that can be supported by the available resources in an area, so as to achieve the highest possible standard of living
(d) Population Density is defined as the number of persons per unit area of land or per square kilometre of land. Population density of a country can be expressed mathematically as:
Population density
Population density = Total population
Land Area
Total Population = Population density x land area
Land area = Total population
Population density
Total Population = Population density x land area
Land area = Total population
Population density
(e) Birth rate (or nationality) of a country refers to the rate at which children are being given birth to in that country. Birth rate may lead to population increase or over population while low birth rate can lead to low population.
Factors affecting the growth of Population
Factors that make population grow can be classified broadly into physical and human factors
(a) Physical factors
(i) Climate: areas with favourable climate like U.S.A, China etc do attract population whle areas of unfavourable or harsh climate like desert and Polar Regions d not attract population
(ii) Availability of water: areas where water is available, both human and agricultural purposes like U.S.A, India etc attracts he population
(iii) Relief: lowlands and river valleys like Nile delta, India etc and lowland plateaux attracts population while high mountains and rugged hills like rockies, andes etc repel population
(iv) Soil: fertile soil tends to attracts population like Ganges of India, Java etc. While infertile soil like those in desert and Polar Regions do not
(v) Presence of mineral resources: the presence of mineral resources like coal, iron, petroleum etc does not attract population
(b)Human factors
(i) Agriculture: areas where agriculture is widely practiced like India, China and Java do not attract population
(ii) Religion belief: The Islamic religion believes in polygamy and early marriages, and these promote high population concentration in an area where it is practiced
(iii) Industry: concentration of industries attract people because of job opportunity
(iv) Immigration: the movement of people from one parts of the world to an area due to the availability of employment opportunities in these areas usually leads to high population concentration
(v) Transportation network: the presence of good transportation network in an area promotes arid facilities migration to increase the population
ASSESSMENT
- Which of the following is a major concern of study about the population of a country?
(a) Population size and distribution
(b) Population growth and processes of population change
(c) Characteristics or qualities of the population
(d) All the above - Which of the following statements about population is correct?
(a) Population is a dynamic phenomenon
(b) The number, distribution and composition of population are static
(c) Population of a country always increases with time
(d) Migrations do not affect the population of a country - The change in the number of inhabitants of a country during a specific period of time is referred to by which of the following terms?
(a) Density of population
(b) Age composition
(c) Population growth
(d) Absolute population - A situation whereby the population is considered too large for the availability resources is known as
(a) Density of population
(b) Over population
(c) Population growth
(d) Absolute population - _____ refers to the rate at which children are being given birth to in a given country
(a) growth rate
(b) birth rate
(c) population rate
(d) development rate
ANSWERS
- d
- a
- c
- b
- b
World Population (II)
Geography, SS 3, Week 2
Topic: World Population (II)
Content:
- Pattern of world population
- Problems of rapid growth population growth
- Advantages and Disadvantages of low and high densities
Pattern of world population distribution is distributed into three; Which are:
(a) The very densely populated parts of the world: the most densely populated areas of the world include
(i) Industrial North – West Europe: this include countries like Great Britain, Franze, German, Denmark, Belgium. These areas are highly industrialized due to the presence of coal and iron
(ii) Industrial North – Eastern U.S.A: this is the great industrial belt of the United States and Canada stretching from the shore of the Great lakes though Pittsburg to New York which is very rich in Coal and iron
(iii) Agricultural Monsoon Asia: This includes populous countries like China, India, Japan, Pakistan, Indonesia etc. This area of largest population concentration of the world, known for fertile soils, warm climate and abundant rainfall which promote agriculture.
(iv) The Nile Valley and Delta: This essentially Eygpt. It is an area within the sahara desert which through irrigation has converted a desert into an area of high agricultural activities and consequently high population
(b) The moderately populated parts of the world
(i) These include areas of cool temperate forest Europe, Canada and Asia.
(ii) The temperate and tropical glass land of Southern continents
(iii) Agricultural U.S.A
(iv) Mediterranean Europe
(v) Africa
(vi) Most part of South Asia
(c) The very sparsely populated pat of the world include:
(i) The cold polar lands of arctic and Antarica which are inhabited due to cold weather
(ii) The Canadian and Eurasian tundra and Greenland also due to cold weather
(iii) The hot deserts of the world like Kalahari, the Atacama, the Sahara etc. Due to the hot weather and dryness no rainfall
(iv) The dense tropical rain forest like the Amazon basin (South America), Congo (Zaire) basin (Central Africa). Both are uninhabited jungles
Problems of rapid population growth
1. High rate of infant mortality is certain in a growing population because of social pressure
2. High mobility will also result in a rapidly growing population
3. Rapid population growth is always accompanied by food shortages
4. The pressure on the low lean social services may led to low life expectancy
5. Malnutrition and diseases
6. Overpopulation always breeds vices such as armed robbery, prostitution etc
7. Inflation is bound to occur, in a situation of growing population
8. Over crowding: growing population always leads to overcrowding
Advantages of High Population Densities
1. High population provides large labour force for industries
2. High population is a source of large market for the goods produced by the industries
3. With large population concentration in an area, there is need for effectiveness planning so that the town can function properly
4. Many people are brought together and this can promote unity among the diverse people in the country
5. Manpower is exported to these regions to enable them earn foreign exchange
6. Organized army in such area is possible
Disadvantages of high population densities
1. Natural resources like fertile farmlands, become over exploited where there is high population growth
2. Areas of high population densities are usually associated with high crime rate like armed robbery, car snatcher, hired assassin etc. These may be due to lack of jobs; hence people resort in crimes
3. Areas of high population densities usually do not have enough jobs for the ever increasing influx of people. This leads to unemployment and underemployment
4. High population concentration leads to scarce or poor accommodation as the house available may not be enough for the high population
5. Many people travel on roads at the same time and ; this leads to traffic congestion most of the time
6. Poor housing, pressure on natural resources and social facilities do lead to environmental pollution
Advantages of low population densities
1. There will be abundance of resources in areas where there and resource endowment
2. The rate of armed robbery, car snatching etc is generally reduced
3. There is no traffic congestion in areas of low population
4. Goods and agriculture products are cheap and easily available due to low population
Disadvantages of low population densities
1. Pipe borne water, electricity etc are grossly under utilized
2. Defence maybe difficult in case of attack
3. As a result of few number of people, the level of revenue may be low
4. There may be inadequate market for manufactured goods
ASSESSMENT
- Great Britain, France, German, Denmark, Belgium areas are highly industrialized due to the presence of
(a) petroleum
(b) gold
(c) bitumen
(d) coal and iron - Pick out the odd one
(a) China
(b) India
(c) Japan
(d) Egypt - Natural resources like fertile farmlands, become over exploited where there is high
(a) population growth
(b) birth rate
(c) death rate
(d) ageing population - One of these is not an advatnage of low population
(a) There will be abundance of resources in areas where there and resource endowment
(b) The rate of armed robbery, car snatching etc is generally reduced
(c) There is no traffic congestion in areas of low population
(d) Pipe borne water, electricity etc are grossly under utilized - One of these is not a moderately populated area
(a) Agricultural U.S.A
(b) Mediterranean Europe
(c) Atacama
(d) Most part of South Asia
ANSWERS
- d
- d
- d
- d
- c
Settlement
Geography, SS 3, Week 3
Topic: Settlement
Content:
- Meaning of Settlement
- Favourable condition for siting a settlement
- Factors affecting population growth
- Types of settlement
- Function of rural and urban settlement
Meaning of Settlement
Settlement is a collection of buildings with people living in them. It is centre of human activities and it consists of houses, communication network, roads, tracks, railways etc. It could be one house, a village, a town or a city.
Favourable conditions for siting a settlement
- There must be adequate and dependable water supply for man use
- The soil must be fertile to produce agricultural activities
- Such lands must be lowland and well drained for easy erection of buildings
- The presence of good roads, railways, airport etc
- The area should be well protected against invading enemies
Factors affecting the growth of settlement
- People are likely to settle in areas that are easily accessible by roads, rails etc nd these tend to increase the growth of settlement
- Absence of both natural and man made disasters in a place tends to attracts people to such areas, hence the growth of such settlement
- Favourable climate also tends to attract people to an area which equally leads to the growth of a settlement
- The presence of low relief or low lands favours settlement unlike rugged relief and highlands which repel settlement of people
- People also settled in places which are seats of government as social amenities and other facilities are often provided in such areas
Types of settlement
There are two types of settlements. These are (a) Rural settlements (b) Urban settlements
(a) Rural Settlement
(i) A rural settlement is a relatively small area with socially homogenous people that know one another
(ii) It could be nucleated, dispersed or linear
(iv) They have people with the same cultural background and language
(v) They have few social amenities and the life style is important
(vi) They are normally involved in primary activities such as farming, fishing and lumbering
Types of rural settlement
There are three types of rural settlement. These are:
- Homestead: this is one family residence. These are disperse settlement which are separated from one another by bushes or by geographical barriers and contain few people with little opportunity for social gathering
- Hamlet: this settlement may be nucleated with few houses, usually less than hundred with many people living in them
- Village: this is a large nucleated rural settlement formed from the combination of several hamlets. It contains several hundred or thousands of people with limited services
Functions of rural settlement
- Agriculture is usually the main occupation of rural dwellers, leading o the production of abundant food
- Most rural areas with forest engage in lumbering activities
- There are few commercial activities, mostly in petty trades, using their small shops and local markets
- Most rural areas with rivers are also involved in fishing
- Rural areas with churches and mosques are involved in religious activities.
(b) Urban Settlement
An urban settlement is relatively large, densely populated settlement with socially heterogeneous people who do not know one another.
(ii) They are usually compact in nature
(iii) They have nucleated settlement
(iv) There is presence of developed infrastructure
(v) They are usually well built areas
(vi) They have centres of innovation and ideas
(vii) They are made of many building; thousands of people live in them
Types of urban settlement
There are four main types of urban settlement and these are:
- Town: it has several thousands of people
- City: this is a large town with greater number of people than town
- Conurbation: this is made up of several towns joined together but, each town still maintains its identity
- Megalopolis: this is the largest type of urban settlement made up of large cities with several millions of people
Functions of urban settlement
- Urban centres are involved in the manufacturing of finished goods
- The presence of markets and banks enables urban dwellers t engage in commercial activities
- Most urban centres are the seats of government
- Urban settlements are centres for the establishment of universities, polytechnic, schools, churches, mosques and hotels
- Where minerals are present in some towns, the inhabitant tend to perform mining function
ASSESSMENT
- Considering types of settlement, people of urban settlement are involved in different activities that includes
(a) business and manufacturing
(b) fishing and farming
(c) mining
(d) forestry - River Nile is located in
(a) Bangkok
(b) Cairo
(c) Cologne
(d) London - _____ is a collection of buildings with people living in them
(a) street
(b) area
(c) local government
(d) settlement - These is not an example of a rural settlement
(a) urban
(b) village
(c) hamlet
(d) homestead - A _______ is the largest type of urban settlement made up of large cities with several millions of people
(a) town
(b) city
(c) conurbation
(d)megalopois
ANSWERS
- a
- b
- d
- a
- d
Environmental Interaction
Geography, SS 3, Week 4
Topic: Environmental Interaction
Content:
- Definition of Environmental Interaction
- Spheres of the environment
- Definition of ecosystem
- Environmental balance
- Food chains and Food webs
- Interaction within the natural environment
- Effects of both natural and human interaction
Definition of Environment and Environmental Interaction
Environment is defined as the total surrounding or medium of any organism in a given area. This include physical surroundings, climatic factors and other living organisms in the surroundings.
Human Environmental Interactions can be defined as interactions between the human social system and (the “rest” of) the ecosystem.
Spheres of the environment
The environment, which is the earth, is grouped into four sphere and these are
- Lithosphere: This is the solid portion of the environment which contain rocks, sand, soil minerals etc
- Hydrosphere: This is the liquid part of the environment like rivers, lakes and oceans
- Atmosphere: This is the gaseous portion of the environment where gases like oxygen, nitrogen, carbon dioxide etc are found
- Biosphere: This is the portion of the environment where plants and animals are found.
Definition of Ecosystem
Ecosystem is defined as the community of plants and animals living together in harmony an interacting with their physical environment. Ecosystem can also be defined s the relationship between organisms (plants and animals) and its physical environment.
Components of Ecosystem
There are two types of ecosystem which include:
(a) Abiotic component: this is the non living component of the ecosystem. It includes the factors or elements like soil, water, gases, sunlight etc
(b) Biotic component: this is the living component of the ecosystem. It includes plants and animals. The biotic component can be grouped into three sub – classes. These are:
(i) Autotrophs: these are called procedures. These green plants which can manufacture their own food from simple inorganic substances through the process of photosynthesis
(ii) Heterotrophs: these are also called primary and secondary consumers. These are organisms which cannot manufacture their own food e.g man, parasites, saprophytes etc
(iii) Decomposers: these are micro organisms that decompose dead organic matter in order to release nutrient required by the producers to prepare their food e.g fungi and bacteria
Meaning of Environmental Balance
Environmental Balance refers to the way of recycling, matter and the flow of energy within an ecosystem in order to ensure continuous supply or availability
Environmental balance is achieved through the following:
- Hydrological (water) cycle: Hydrological (water) cycle is the exchange or circulation of water between the oceans, the atmosphere and the land. The atmosphere receives the water through evaporation from ocean, rivers and from land.
- Carbon cycle: Carbon cycle involves the series of processes which contribute to the circulation of carbon in nature. Carbon is circulated in form of carbondioxide
- Mineral nutrient cycle: Mineral nutrient cycle refers circulation of mineral nutrient between plants and the soil. These mineral nutrient include mineral, calcium, iron, sodium, sulphur, potassium etc:
- Nitrogen cycle: Nitrogen cycle involves the complex process by which nitrogen is circulated between the atmosphere, soil, pant and animals. Plant can only use nitrogen in form of nitrate
- Food chain and food web
Food chain tropical level and food web
Food chain is defined as the linkage of a series of organisms in a habitat through the flow of energy of consumer levels and their nutritional sequence. Food chain also involves the transfer in which each organism feeds on one before it in a sequence. Example of food chain is as follow
Grass Sheep Man
Grass Grasshopper Toad Snake Hawk
Tropical level refers to the feeding stages found in a food chain example
Grass Grasshopper Toad Snake Hawk
1 2 3 4 5
The first in each group is usually called autotrophs (or producer) e.g grass, while the next e.g sheep is called the primary consumer while the last e.g man is called the secondary consumer.
The trophic level refers to the feeding stages found in a food chain
Food web
Food web is defined as the complex feeding relationship of an organisms made up of many interrelated food chains. It involves a wider range of energy transfer. The food web consist of five different food chains
ASSESSMENT
- ______ is defined as the total surrounding or medium of any organism in a given area
(a) food web
(b) environment
(c) atmosphere
(d) climate - The solid portion of the environment which contain rocks, sand, soil minerals is known as the
(a) lithosphere
(b) hydrosphere
(c) atmosphere
(d) biosphere - The interactions between the human social system and (the “rest” of) the ecosystem is known as
(a) environmental support
(b) environmental care
(c) environmental interaction
(d) environmental web - _____ are organisms that cannot manufacture their own food
(a) autotrophs
(b) decomposers
(c) heterotrophs
(d) biotrophs - The linkage of a series of organisms in a habitat through the flow of energy of consumer levels and their nutritional sequence is
(a) food chain
(b) food necklace
(c) food watch
(d) food brace
ANSWERS
- b
- a
- c
- d
- a
Environmental Intervention
Geography, SS 3, Week 5
Topic: Environmental interventions
Content:
- Definitions of environmental Intervention
- Types of environmental intervention
- Intervention within the natural environment
- Effects of both natural and human interaction
Definition of Environmental Intervention
Environmental Intervention refers to the forces of nature and the activities of man that change the natural existence of the components of ecosystem
Types of environmental intervention
There are two types of environmental interventions in our environment. These are natural and human interventions
(a) Natural intervention; It is caused by a number of natural process which include:
(i) Desert encroachment (ii) Vulcanism
(iii) Sea level changes (iv) Earthquakes
(v) Tectonic movement (vi) Climatic changes
(vii) Drought (viii) Hurricane (ix) Flooding
The effects of Natural intervention
- New features different from those initially there are produced e.g volcanism creates volcanic mountain
- Changes in the landscape of the area
- Raising and lowering beaches
- Widespread destruction or extinction of aquatic life
- Displacements of animals
- Displacement of man
(b) Human intervention; It include the following
(i) Deforestation (ii) Land reclamation
(iii) Pollution (iv) Farm activities
(v) Mining/Quarrying (vi) Construction
(vii) Cloud seeing (viii) Fishing
(ix) Hunting (x) Industrialization
(xi) Urbanization (xii) Grazing
Deforestation causes increased run off and flooding. It leads to destruction of natural habitats. Deforestation leads to energy balance, erosion and reduction in rainfall
Land reclamation leads to less rainfall and changes in drainage pattern. Land reclamation reduces amount of soil moisture and loss of some organisms and plants
Pollution (soil, atmospheric and noise): atmospheric and water pollution leads to the loss of plants and animal life. Oil spillage and water pollution alter the types of plant that can grow in an area. Land pollution exposes the soil surface and also changes the chemical composition of soil.
Grazing: overgrazing leads to the reduction of agricultural land. It depletes the vegetative cover of the soil. Grazing leads to the compaction through excessive trampling by animals and also destroys the soil structure and causes soil erosion.
Farming activities causes the destruction of weeds and burns the organic matter content of the soil. It causes the destruction of pests and natural habitat.
Mining causes pollution of the land, surface and underground water also causes reduction of farm lands. Mining also leads to the disintegration of settlement
Urbanization causes reduction in agricultural land. Wastes produced by urbanization produce pollution and can lead to loss of some organisms and plants.
Construction destroys the soil structure and causes soil erosion. Construction can also kill plants and animals.
ASSESSMENT
- ____ refers to the forces of nature and the activities of man that change the natural existence of the components of ecosystem
(a) environmental occupation
(b) environmental sanitation
(c) environmental intervention
(d) environmental integration - Natural intervention can be caused y the following except
(a) Desert encroachment
(b) Vulcanism
(c) Deforestation
(d) Sea level changes - _____ exposes the soil surface and also changes the chemical composition of soil.
(a) grazing
(b) land pollution
(c) land reclamation
(d) deforestation - One of these is not a human intervention
(a) fishing
(b) industralization
(c) hunting
(d) drought - One of these is not true of grazing
(a) reduction of agricultural land
(b) afforestation
(c) compaction
(d) cause of soil erosion
ANSWERS
- c
- c
- b
- d
- b
World Trade
Geography, SS 3, Week 6
Topic: World Trade
Content:
- Definition of Trade
- Division of International trade
- Importance of international trade
- Factors affecting international trade
- Major commodities involved in international trade
Definition of Trade
Trade refers to buying and selling or exchange of goods and services between one region and another in the same country or between one country and another
Division of international trade
(a) Import trade involves the buying of goods and services from another country into your own country
(b) Export trade involve the selling of goods and services produced in one’s country to another country
Importance of international trade
- International cooperation is fostered between two nations which are involved in international trade
- New products that would otherwise have been unavailable in a country are provide
- Jobs are provided through activities involved in the exportation from the sales or export of their goods to another country
- Export goods or products are easily stimulated through increased production in the source region
- Through international trade, skills and expertise are exchange between nations
Factors affecting international trade
- The difference in climate favours the growth of different crops for export
- The higher the differences in production of agricultural goods, the greater the volume of trade between two countries and vice versa
- The need to earn foreign exchange helps to increase the volume of trade between nations
- The higher the difference between prices of goods, the greater the volume of trade between two countries and vice versa
- The higher the import duties imposed goods and services, the lesser the goods that will be imported and vice versa
Major commodities involved in international trade
(a) Nigeria’s export: Nigeria usually exports agricultural goods and minerals products to her foreign partners
(i) Mineral products: e.g petroleum or crude oil, tin, columbite etc
(ii) Agricultural goods: .g cocoa, groundnut, palm kernel, rubber, timber, cotton, hides and skin.
(b) Nigeria’s imports
(iii) Manufactured goods: Nigeria usually imports manufacture goods e.g computers, motor vehicles, tractors and machines etc
Factors which may limit international trade
- Inadequate production of goods, either by importing or exporting country can limit
- Their will be low sales when the other country’s demand for products is low
- High tariff charged by certain country can affect the rate of import or exports of goods to that country
ASSESSMENT
- _____ buying and selling or exchange of goods and services between one region and another in the same country or between one country and another
(a) trade
(b) exchange
(c) import
(d) export - Export trade involves the buying of goods and services from another country into your own country
(a) true
(b) false - International cooperation is fostered between two nations which are involved in international trade
(a) true
(b) false
ANSWERS
- a
- b
- a
Map Work
Geography, SS 3, week 7
Topic: Map work
Content:
- Contour representation of land form
- Types of slope
- Gradient and vertical exaggeration
- Cross section drawing and intervisibility
Contour representation of land form
The following are some common landforms or relief features that can be represented on map by using contour lines.
- Valleys: They are lowland between two highlands. Valleys are represented by V- shaped contour lines with the apex of the V- shape pointing towards the highland. When a valley contains water, it is called a river valley but when it contains no water, it is called a dry valley
- Spurs: They are projection of highlands into low ground. That is the V-shape points to the lowland spurs separate one valley from another and the contour numbering decreases outward.
- Conical Hill: They are usually circular in shape and become smaller and smaller towards the centre
- Round top: This hill are contours showing round top hills that are circular but do not taper to a points. The inner most circle of contour is fairly large
- Isolated Hill: This is a hill which stands apart or is far removed from other hills or highlands. It may either be round or conical in shape
- Knoll: This is an isolated peak of few metres high, associated with a highland.
- Ridge: This is a strip of highland which is elongated and narrow. He contour run almost parallel to each other
- Col or Saddle: This is a stretch of lowland which separates two highland areas on a ridge, two peaks are usually separated by a col. There is no much difference between a cola and a saddle. The only difference is that the saddle is wider than the col
- Pass or Gap: This is also a col but is found at lower parts of highland. A pass separates two highlands but at lower level. A pass is always a col, but a col is not always a pass. A col becomes a pass when it is used or likely to be used as a route way, either for footpath, road or railway
- Plateau: It is an extensive and broad highland area with a comparatively level surface. Plateaux usually have a steep side, if a plateau is cut off by a number of river valleys; most of the original level surface is removed by erosion, leaving behind flat top peaks. Such plateau is dissected plateau
- Escarpment/ Cuesta: Escarpment refers to steep slope or the precipitous face of a ridge. The contour lines are closely packed.
- Cuesta: It refers to a hill with a steep slope(dip) on one side and a gentle slope (scarp) on the other. Therefore dip + scarp = Cuesta
- Gorge: It is a steep sided valley with a river or stream.
- Watershed is a highlands area which separates the headstream of rivers flowing in different directions but rising from the same mountainous source
- Undulating Lowland gently rises and falls with low level is usually shown by irregular and well spaced contours
- Flood Plain is lowland, bordering a river, formed by deposits of sediments carried down by a river. It is generally referred to as area liable to flooding; it is very good for the cultivation of swamp rice
Types of slopes
The nature of slope in any land surfaces can also be represented by contour lines. The various type include:
- Even or uniform slope: the contour lines in these slope is uniformly spaced. It means, the degree of steepness is the same throughout the slopes
- Gentle slope: this occurs when the contour lines are far apart or widely spaced
- Steep slope: this occur when the contour lines are very close to one another or they are closely packed
- Concave slope: this is the combination of both steep and gentle slopes. When asceding concave slope, one passes the area which has gentle slope first before reaching the area with a steep slope. Contour lines are widely spread at the lower level and become closely packed at the higher level. Visibility of both ends is possible concave slope.
- Convex slope: this is the opposite of concave slope. The contour lines are closely packed together at lower level. Visibility is not possible
Calculation of gradients and vertical exaggeration
(a) Gradient: the gradient of an area is the slope of ground expressed as a ration between the heights and the lengths of the ground slopes are of various steepness.
Formula for calculating gradient = Differences in height (metres) or Vertical interval (V.I)
Horizontal distance (metres) Horizontal Equivalent (H.E)
(b Vertical Exaggeration is defined as the number of time vertical heights are exaggerated or enlarged in relation to the horizontal distances.
Formula for calculating vertical exaggeration = Horizontal scale
Vertical scale
Cross section drawing and intervisibility
(a) Cross section or relief : It is defined as the practice whereby relief shown by contours on map are drawn to bring out real appearance of such relief as it is on the ground. Cross section shows the nature of the relief that is represented by contour lines at a glance.
(b) Intervisibiity is defined as a way of knowing whether one point or place on the map can be seen from another point o place on the same map within the limit is of physical sights cross section drawing can help to know if two points on a map are intervisible or not.
ASSESSMENT
- ___ refers to steep slope or the precipitous face of a ridge
(a) knoll
(b) enscarpment
(c) plateau
(d) gorge - An extensive and broad highland area with a comparatively level surface is known as
(a) knoll
(b) enscarpment
(c) plateau
(d) gorge - An isolated peak of few metres high, associated with a highland is a/an
(a) knoll
(b) enscarpment
(c) plateau
(d) gorge - _____ occur when the contour lines are very close to one another or they are closely packed
(a) gentle slope
(b) steep slope
(c) concave slope
(d) convex slope - _____ is defined as a way of knowing whether one point or place on the map can be seen from another point or place on the same map
(a) cross section
(b) watershed
(c) intervisibility
(d) dual visibility
ANSWERS
- b
- c
- a
- b
- c
Interpretation of topographical maps
Geography, SS 3, Week 8
Topic: Interpretation of topographical maps
Content:
- Important features that need interpretation
- Relief (procedures for interpreting relief)
- Drainage (procedures for interpreting drainage)
- Settlement (procedures for interpreting settlement)
Important features that need interpretation include relief, drainage, settlement, communication and land use relief
Procedures for interpreting relief
- Use contour lines, spot heights or trigonometrical station to note the highest point and the lowest point on the land. The highest point is found on the highest contour lines while the lowest point i found on the lowland
- Note the preparation of the land occupied by highlands and low lands
- Note the specific land form and relief whether a ridge, hill, plateau, knoll, plain
- Note the location or direction of these relief features like plateau, hill, ridge, etc on map
- Note the heights of the lowlands above the sea level and whether they are flat or plains of undulating
- Note if the hills and plateaux are dissected or not
Drainage
Procedures for interpreting drainage
- Find out the important rivers on the map
- Note the direction of flow of rivers
- Find out the pattern of drainage either on the whole part of the map
- Look out for watershed which separate drainage system
- Note if there are marshy areas which are usually poor drained and are liable to flooding
- Note if there are other water bodies like lakes, oceans, boreholes and identify their locations on the map
- Do the rivers have delta or estuary
Settlement
Procedures for interpreting settlement
- Find out the type of settlement is rural or urban. Urban settlement are found in cities and towns with compacted buildings, presence of good roads and Basic infrastructure.
- Note the pattern of settlement whether linear, nucleated or dispersed.
- Relate settlement of relief: That is i.e are the settlements located on highlands ,plateaux,ridge or on lowlands and give reasons for such settlement
- Relate settlement to drainage : That is the settlement along the river contours far from rivers,near a lake ocean or far from marshy areas and give reasons for such settlement.
- Relate settlement to communication: Is the settlement linear, i.e along the road ,railway far from the airport or along a navigable river or lake?
- Describe also areas which are not settled and give reasons why they are uninhabitable
Communication
Procedures for interpreting communication
- Find out the means of communication: That is by road ,railway,footpath,air(if there re airports) and rivers (if there are navigable rivers or lakes)
- Note from conventional sign: If the roads are primary, secondary or minor roads
- Relate communication to relief: Do the roads,railways or footpaths avoid steep slopes, passes through highlands, ridge or are they located on the lowlands?, Are there passes etc?
- Relate communication to settlement: The are presence of major road is an indication of commercial or industrial town while minor roads and footpaths are common features of rural settlements
- Note important natural and manmade features like mountains, lakes, ridge, boreholes, factories which one may across when travelling from one area to another
Land Use
Land use refers to the various ways in which man uses land. In other word , the use of the land by man is a reflection of the functions of that settlement.
The useful means for interpreting the land use, function or importance of a particular settlement
| Features from conventional signs on a map | Uses of land or function of settlement |
| Presence of building | Residential |
| Presence of mineral resources | Mining |
| Presence of forest | Farming and lumbering |
| Presence of grasses | Livestock and farming |
| Presence of rivers | Fishing and canoe building |
| Presence of prison, court, police station | Administration |
| Presence of banks and market | Commercial |
| Presence of hotel and stadium | Social functions |
| Presence of schools | Educational |
| Presence of marshy area | Swamp rice cultivation |
| Presence of hospital | Health function |
| Presence of industries | Industrial function |
ASSESSMENT
- On a topographic map, the closer the contour lines the
(a) lower the elevation
(b) gentler the slope
(c) flatter the land surface
(d) steeper the slope - A scale of 1:1000 on a topo map indicates that
(a) 1 unit on the map equals 1000 units in the real world
(b) the map represents the entire Earth
(c) 1 unit on the map is greater than 1 unit in the real world
(d) 1000 units on the map equals 1 unit in the real world - If the contour interval on a topo map is 10 meters, and one contour line is labeled 50 m
(a) the adjacent contour line would represent 60 m in elevation
(b) the adjacent contour line would represent 20 m in elevation
(c) the adjacent contour line would represent 150 m in elevation
(d) the adjacent contour line would represent 10 m in elevation - When you observe contour lines with hachures on a topographic map, this indicates that
(a) the elevation of this area is increasing
(b) a depression is located in this part of the map
(c) you are entering a mountainous area
(d) you have crossed a stream - How are streams indicated on a topographic map?
(a) by contour lines that form v’s which point upstream
(b) by contour lines that form u’s which point upstream
(c) by contour lines that form v’s which point downstream
(d) by contour lines that form u’s which point upstream
ANSWERS
- d
- a
- a
- b
- a