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Population Dynamics and Migration
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What is a Census?
A census is a count of the population of a
country. A census also f inds out f acts about thepopulation, such as their age, sex, jobs they do,
type of house and what language they speak. It
is usually carried out every 10 years.
Why do you think it¶s important to take a census?
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What is a Census?
A country will carry out a census because:
The government needs to know how many
people live in each part of their country; it then
knows where to spend its money
They also f ind out about population trends; this
allows them to plan ahead
They can f ind out about the population structure -
how many old, middle aged and young people there
are; this again allows the government to target their
spending - on, for example, retirement homes or
schools
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Census Difficulties
Some countries have a lot of diff iculty carrying out
censuses and some countries don't have censuses
at all. The reasons for this are
They cost a l
otof
money which p
oor c
ountriescan't afford
Some people live in diff icult to reach areas
Wars make counting diff icult
Nomads also make counting diff icultPeople who are illiterate are unable to f ill out the
forms
Some people do not tell the truth for political or
religious reasons
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Vital Registrations
This is a method of counting the population by
caref ully using the records of births, marriages,
adoptions, divorces and deaths. This method is
cheaper, but it does not give as much informationas a census. It does, however, give a continuous
record, whereas a census gives a "snap-shot"
picture every 10 years.
Another way is by a sample survey where af raction of the population are surveyed. This
method has the advantage of being cheaper than
a census, but the disadvantage of being less
accurate.
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How Is the Population Distributed?
People do not live evenly spread thr ough the
world. Large parts of the world are very sparsely
populated (low population density), whereasothers are cr owded (high population density). The
spread of people ar ound a country is known as its
population distr ibution
Areas with high population include WesternEur ope, the Eastern states of the United States,
India, Japan and China.
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How Is the Population Distributed?
The f actors that tend to pr oduce low population
density (negative f actors) are
Extreme climate - too cold, hot, wet or dry Extreme relief - too high and too steep
Extreme remoteness - places that are diff icult
to reach
Inf ertile land - need to have extensive (verylarge) f arms
Backwards economy, with low pr oductivity
economic activities
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How Is the Population Distributed?
The f actors that can pr oduce a high population
density (positive f actors) are
Moderate climate
Fertile f arming land Mineral resources - mines pr oduce jobs, and
pr ovide raw materials for other industries
Low land - with gentle slopes or f lat gr ound
Good water supply
Wealthier areas - people will move to where the
jobs and money are found
A long history of land occupation
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How Is the Population Distributed?
Choroplethmap showing population distribution
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How Is the Population Distributed?
Cartogram showing population distribution by countries
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How Is the Population Distributed?
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Now let¶s play...
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Causes of Population Growth
Population growth is the balance among birth-rate,
mortality rate and migration:
If there are more births than deaths in a year therewill be what is called a natural increase of
population. In the opposite case, there will be a
natural decrease.
To give account of the whole population of an area(country, region, etc.), migrations must be
considered as a complementary factor to natural
growth.
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Causes of Population Growth
In order to compare the different rates of population
growth two indicators are used:
Birth rate: the number of babies born alive per thousand of people per year.
Br=Births/Population·1000
Death rate: the number of deaths per thousand of
the population per year.
Dr=Deaths/Population·1000
Migration: the number of people moving in or out.
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Causes of Population Growth
Differences in birth rates may be classified as:
Socio-economic: age of marriage, work of
women, wealth level, age-sex structure, poverty
levels, infant mortality rate...
Cultural: female literacy levels, religious beliefs
Political factors: policies adopted by governments
in order to encourage or discourage births,
conflict...
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Causes of Population Growth
Differences in death rates are essentially socio-
economic:
Age of population Nutrition levels
Access to fresh water
Hygiene levels
Amount and quality of health services available Levels of conflict and violent crime
Actividad
Population
explosion
worksheet
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Demographic Transition Model
Fotocopiar gr áf ico
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Fotocopiar gr áf ico
The structure by age of any population has important
economic consequences. One of them is derived from
the Dependency Ratio, defined as the proportion between the working (people between 16 and 64 years
old) and the non-working (people between 0 and 16
years old and over 65 years old) parts of a given
population.It is worked out with the following formula: D.R.=
(people under 16) + (people over 65) / (people between
16 ± 65).
What Is a Dependency Ratio?
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What Is a Dependency Ratio?
Spain (2010)
0-14: 5,888,000; 15-64: 27,213,000 ; 65+: 7,447,000
DR = (5,888,000 + 7,447,000 / 27,213,000) = 0,49
Angola (2010)
0-14: 5,670,000; 15-64: 7,044,000; 65+: 353,000
DR = (5,670,000 + 353.000 / 7,044,000); Td = 0.85
In the case of Spain, for each person in working age there
is 0,49 dependent people; in the case of Angola, 0,85.
This sometimes is transformed into a percentage
multiplying by 100.
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What Is a Dependency Ratio?
The results have a bearing on the education, health and
social security policies of governments.
Countries that have a high dependency ratio have more people who are not of working age, and fewer who are
working and paying taxes. The higher the number, the
more people that need looking after, which results in
increased expenses in health, education or retirement pensions
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Population Pyramids
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Population pyramids are used to show information aboutthe age and gender of people in a specific country.
Male Female
Population in millions
In thiscountry
there is ahigh Birth
Rate
There isalso a high
DeathRate.
This population pyramid is typical ofcountries in poorer parts of the world
(LEDCs.)
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In some LEDCs the
government isencouraging couples tohave smaller families.This means the birth
rate has fallen.
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Male Female
Population in millions
In thiscountry the
number ofpeople in eachage group isabout the
same.
The largestcategory ofpeople wereborn about
40 yearsago.
In this country there is a low Birth Rateand a low Death Rate.
This population pyramid is typical ofcountries in the richer parts of the world
(MEDCs.)
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Population in millions
Male Female
In this
country thebirth rate isdecreasing.
In the future the
elderly people will makeup the largest sectionof the population in this
country.
This is happeningmore and more in
many of the world·sricher countries.
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Male
Female
Population in thousands
This country has a largenumber of temporary
workers. These are peoplewho migrate here especially
to find a job.
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What is going to happen to
Japan·s population in thefuture?
Why does this matter?
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Is Indian population expanding
now?
What makes you think so?
What is going to happen withIndian population in the future?
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Your task:
Open your own PowerPoint presentation.
Go to www.census.gov www.census.govSelect Search and type in IDB.
Select International Database
From here select Population Pyramids.
Find a population pyramid typical of a poor country (LEDC) copy andpaste it into your PowerPoint document then add labels to explain whatis shown.
Repeat for an MEDC (rich) country.
For a country of your choice copy and paste the pyramids for 2000,2025 and 2050.
Write about what the graphs show and try to give reasons for thepatterns. Explain how the population of this country is changing and sayhow that could affect the country.
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W
hen you have finished;Find out some background information on eachcountry and add this to your presentation.
Concentrate on facts and figures which you can
use to compare the countries such as % of thechildren at school, type of jobs available, how richor poor (GDP per capita.)«««
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Migrations
Migration is the movement of people f r om one
place to another, implying a change of residence
or address.
Actividad
Population
explosion
worksheet
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Migrations
Migrations can be classified in several ways:
Depending on the destination, they can be
national, international or even intercontinental.
Depending on the motives they can be economic, political or religious. In the latter cases we talk
about refugees, not emigrants.
Depending on the duration, they can be temporary
or definitive. Depending on the will of the migrants, they can be
voluntary or forced.
Give an example of each type of migration
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Migrations
From the previous framework some specific examplesof migrations must be singled out:
International migrations from LEDCs to MEDCs, due
to economic causes.
Rural-urban migrations, common in LEDCs Brain Drain migrations of highly qualified people.
Counter -urbanisation in MEDCs, from cities to rural
areas, which increases the number of commuters.
Refugees, forced to leave their country due to hardship
or political oppression
Make a guess about the pushing and pulling factors behind
each example