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
- 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
The population density of a country is has very little to do with its level of economic development.
-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).
-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.
Factors affecting population density
Factors attracting settlement-temperate climate, low-lying flat fertile land, good supplies of natural resources, e.g building resources
Factors discouraging settlement-extreme climates,mountainous or highland areasdense vegetation e.g. the Amazon Rainforest
Such as the availibility of jobs, and high wages can contribute to high population density though migration. Migrants get attracted to these factors.
Civil War- poeple leave the area
Global Population Growth
At present the world's population is growing quickly, though this has not always been the case.
Ways to show population size:
Population pyramid-comparing relative numbers of people in different age groups is divided up between male and female.
Demographic transition models- show population change over time, cut up into different stages to do with birth and death rate.
The 3 main causes of population change: Birth, Death and Migration.
natural increase = birth rate - death rate
The difference between the birth rate and the death rate of a country or place is called the 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.
MEDCs have low population growth rates, with low death rates and low birth rates.
LEDCs have high population growth rates. Both birth rates and death rates tend to be high. However, improving healthcare leads to death rates falling - while birth rates remain high.
Population will decline if death rate is greater than birth rate.
Population will increase if death rate is less than birth rate.
The demographic transition model
The five stages of the demographic transition model
- Total population is low but it is balanced due to high birth rates and high death rates.
- Total population rises as death rates fall due to improvements in health care and sanitation. Birth rates remain high.
- Total population is still rising rapidly. The gap between birth and death rates narrows due to the availability of contraception and fewer children being needed to work - due to the mechanisation of farming. The natural increase is high.
- Total population is high, but it is balanced by a low birth rate and a low death rate. Birth control is widely available and there is a desire for smaller families.
- Total population is high but going into decline due to an ageing population. There is a continued desire for smaller families, with people opting to have children later in life.
Key things to know: It gives us information about birth and death rates as well as life expectancy.A population pyramid tells us how many dependants there are. Many LEDCs have a high number of young dependants, whilst many MEDCs have a growing number of elderly dependants.
Changing overtime and the shape:
-One that is very triangular shows that there is low life expectancy.
-One that has fairly straight sides (more like a barrel) shows a population with a falling birth rate and a rising life expectancy.
-Places with an ageing population and a very low birth rate would have a structure that looks like an upside-down pyramid.
-As a country develops, the shape changes from triangular to barrel-like.
Population growth in LEDCs
Most LEDCs are experiancing rapid population growth.They have falling death rates, due to improving health care, while birth rates remain high. Causes:
-Limited access to contraception and info. Contraception might 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. And help care of other family members
-High rates of 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.
Population change in MEDCs
Most MEDCs are experiencing slow rates of population growth and some are experiencing population decline.
The population is high, but not growing. Some countries have a declining population. This means that the birth rate in their country has fallen below the death rate.
Life expectancy is rising due to improved health care (contraception), activities available and information on how to live a healthy life.
As birth rates fall and people have smaller families, the number of elderly dependants is rising. To try to balance out an ageing population some countries have a pro-natalist policy- they encourage people to have more children by offering them benefits, like access to care and maternity leave.
Managing population growth
Countries need to control rapid population growth so they dont become over populated. Tehy also need to develp a way that is susatinable:
Birth control prpgrammes- Having laws about how many children your alowd to have, offering free contrception and sex education. Couples are sometimes given benefits, housing, maternity leave and free education for that child if they have one child only.
Immigration laws- govs can limit the amount of people that are allowed to move and live in another country permanently, they can be selective on what age they choose.
NEGATIVE IMPACTS ON OVER POPULATION
-Too many people less jobs available, more litter and pollution emitted, increased poverty as more children are born into poor families, aren't enough houses, healthcare services cant cope with that many people, and more natural resources are used up.