Population Notes

Transcription

Population Notes
Population and Settlements
People are unevenly distributed around the world. The difference in distribution is measured
by comparing population density - the number of people per square kilometre (km²).
Population density is determined more by environmental factors, which make an area more or
less attractive to settlers than by economic development.
Population patterns
The way in which people are spread across a given area is known as population
distribution. Geographers study population distribution patterns at different scales: local, regional,
national, and global.
Patterns of population distribution tend to be uneven. For example, in India, there are more people
living in Mumbai than in north-east India.
Population density
The map shows patterns of population density on a global scale. Note that: areas of high and low
population density are unevenly spread across the world; the majority of places with high population
densities are found in the northern hemisphere
Map of the world showing population density
Key:
Population density
Population density is the average number of people per square kilometre. It is a way of measuring
population distribution and shows whether an area is sparsely or densely populated. Population
density is calculated using the following formula:
Population density = total population ÷ total land area in km²
(practice solving the above equation to find population density)
The population density of a country is has very little to do with its level of economic development.
For example, both Bangladesh and Japan are very densely populated, but Bangladesh is a LEDC and
Japan is a MEDC.
Factors affecting population density
Environmental and human factors affect the spread of people across the world.
Factors attracting settlement
• temperate climate, eg the UK
• low-lying flat fertile land, eg the Bangladesh Delta
• good supplies of natural resources, eg building resources
Factors discouraging settlement
• extreme climates, eg Sahara Desert
• mountainous or highland areas, eg the Himalayas
• dense vegetation, eg the Amazon Rainforest
Socioeconomic factors
Factors such as the availability of jobs and comparatively high wages can contribute to high
population density through migration. For example, from 2004 the UK has seen an influx of migrants
from countries that have recently joined the EU, such as Poland.
Political factors
Civil war, eg in the Darfur region of Sudan, can contribute to lower population densities as people
become refugees and leave an area.
Global population growth
Population pyramids show the structure of a population by comparing relative numbers of people
in different age groups. Population structures differ markedly between LEDCs and MEDCs.
Demographic transition models show population change over time - and also show marked
differences between LEDCs and MEDCs.
At present the world's population is growing quickly, though this has not always been the case.
Until the 1800s the world's population grew slowly for thousands of years.
In 1820 the world's population reached one billion.
In the early 1970s, the world's population reached three billion.
In 1999, less than 30 years later, the population doubled to six billion.
The global rate of population growth is now one billion every 15 years.
The graph shows this pattern of accelerating growth (including the predicted population for 2025).
World population growth 500BC - 2025
Causes and rates of change
The three main causes of population change
Births - usually measured using the birth rate (number of live births per 1,000 of the
population per year).
Deaths - usually measured using the death rate (number of deaths per 1,000 of the population
per year).
Migration - the movement of people in and out of an area.
Rate of change
Births and deaths are natural causes of population change. The difference between the birth rate and
the death rate of a country or place is called the natural increase. The natural increase is calculated
by subtracting the death rate from the birth rate.
natural increase = birth rate - death rate
The rate of natural increase is given as a percentage, calculated by dividing the natural increase by
10. For example, if the birth rate is 14 per 1,000 population, and the death rate is 8 per 1000
population, then the natural increase = 14 - 8 = 6. That is 6/1000, which is equal to 0.6 per cent.
(use the chart below to practice solving the above equation to find natural increase)
Patterns of population growth
Rates of population growth vary across the world. Although the world's total population is rising
rapidly, not all countries are experiencing this growth. In the UK, for example, population growth is
slowing, while in Germany the population has started to decline. MEDCs have low population
growth rates, with low death rates and low birth rates.
Population will decline if death rate is greater than birth rate.
Population will increase if death rate is less than birth rate.
LEDCs have high population growth rates. Both birth rates and death rates in LEDCs tend to be high.
However, improving healthcare leads to death rates falling - while birth rates remain high.
The table shows data in selected LEDC and MEDC countries. The figures are per 1,000 of the
population per year.
MEDCs
Country
Birth
Death rate Natural increase
Population growth rate (%)
rate
UK
11
10
1
0.1
Canada
11
7
4
0.4
Bulgaria
9
14
-5
-0.5
LEDCs
Country
Birth
Death
Natural
Population growth rate (%)
rate
rate
increase
South Africa
25
15
10
1
Botswana
31
22
9
0.9
Zimbabwe
29
20
9
0.9
9
14
In Bulgaria, the birth rate is /1,000 and death rate is /1,000. As birth rate is less than the death rate,
Bulgaria has a declining population.
In South Africa, the birth rate is 25/1,000 and death rate is 15/1,000. South Africa has an increasing
population with a population growth rate of 1 per cent.
Population structure and population pyramids
Population structure means the 'make up' or composition of a population. Looking at the population
structure of a place shows how the population is divided up between males and females of different
age groups.
Population structure is usually shown using a population pyramid. A population pyramid can be
drawn up for any area, from a whole continent or country to an individual town, city or village.
The following graphs show the population pyramids of an MEDC (the UK) and an LEDC
(Mozambique), for 2000. The left side of each pyramid shows the number of men in each age group,
the right side shows the number of women in each age group.
Population pyramid for the UK 2000
Population pyramid for Mozambique 2000
Now compare the UK population pyramid with those for Mozambique:
In this graph, notice that in 2000 the 0-4 age group contained the largest number of people, with the
numbers thereafter declining steadily as the ages increase. The graph matches stage 1 in the model.
Population growth in LEDCs
Most LEDCs are experiencing rapid population growth. Most LEDCs are in stage 2 or 3 of the
demographic transition model. This means that they have falling death rates, due to improving health
care, while birth rates remain high. The recent history of population management policies in China
illustrates population-change management problems.
Causes of population growth in LEDCs
Limited access to family planning services and education about contraception. Contraception
and other methods of family planning may not be culturally or religiously acceptable.
Children are a valuable source of labour and income for a family. They can work on the land
from a young age and as they get older they can earn money in other jobs.
Children can help to care for younger children and elderly family members.
High rates of infant mortality (infant deaths) mean that women need to have many children in
order to ensure that some survive through to adulthood.
It may be traditional or culturally important to have a large family.
LEDCs have a high population-growth rate which means that they have many young dependants.
Governments in LEDCs and international bodies and charities are working to reduce birth rates and
slow down rates of population growth.
Youthful population
The high birth rate in LEDCs results in a high proportion of the population under 15. This youthful
population gives a country specific problems.
The problems include:
1. Young children need health care - for example, immunisations. This is expensive for a country
to provide.
2. Young people need to be educated - providing schools and teachers are expensive. Resources
for lessons are difficult to access, and costly to buy.
In the future, more children will reach child bearing age, putting more pressure on the health service.
Case study: China
In the late 1970s, the Chinese government introduced a number of measures to reduce the country's
birth rate and slow the population growth rate. The most important of the new measures was a onechild policy, which decreed that couples in China could only have one child.
In 1950 the rate of population change in China was 1.9 per cent each year. If this doesn't
sound high, consider that a growth rate of only 3 per cent will cause the population of a
country to double in less than 24 years!
Previous Chinese governments had encouraged people to have a lot of children to increase
the country's workforce. But by the 1970s the government realised that current rates of
population growth would soon become unsustainable.
The one-child policy
The one-child policy, established in 1979, meant that each couple was allowed just one child.
Benefits included increased access to education for all, plus childcare and healthcare offered to
families that followed this rule.
Problems with enforcing the policy:
1. Those who had more than one child didn't receive these benefits and were fined.
2. The policy was keenly resisted in rural areas, where it was traditional to have large
families.
3. In urban areas, the policy has been enforced strictly but remote rural areas have been harder
to control.
4. Many people claim that some women, who became pregnant after they had already had a
child, were forced to have an abortion and many women were forcibly sterilised. There
appears to be evidence to back up these claims.
Impact of the policy
The birth rate in China has fallen since 1979, and the rate of population growth is now 0.7 per
cent.
There have been negative impacts too - due to a traditional preference for boys, large
numbers of female babies have ended up homeless or in orphanages, and in some cases
killed. In 2000, it was reported that 90 per cent of foetuses aborted in China were female.
As a result, the gender balance of the Chinese population has become distorted. Today it is
thought that men outnumber women by more than 60 million.
Long-term implications
China's one-child policy has been somewhat relaxed in recent years. Couples can now apply to have
a second child if their first child is a girl, or if both parents are themselves only-children.
While China's population is now rising more slowly, it still has a very large total population (1.3
billion in 2008) and China faces new problems, including:
the falling birth rate - leading to a rise in the relative number of elderly people
fewer people of working age to support the growing number of elderly dependants - in the
future China could have an ageing population
Population change in MEDCs
Most MEDCs are experiencing slow rates of population growth and some are experiencing
population decline.
Most MEDCs are in stage 4 of the demographic transition model - the population is high, but not
growing. Some countries have a declining population and could be said to be entering stage 5. This
means that the birth rate in their country has fallen below the death rate. Most MEDCs have a very
low rate of natural increase.
The average life expectancy in MEDCs is rising. This is due to:
improvements in health care and medicine
increased leisure and recreation time
improved knowledge about the importance of a balanced diet and regular exercise
improved living standards and quality of life
Birth rates in MEDCs are falling as people choose to have smaller families later in life.
Contraception is easily available and well understood.