Case study: Bristol
Bristol's population is made up of 13.9% black and minority ethnicity residents. This is similar to the national average of 12.5%. However the different ethnic groups are not spread evenly across the city.
Bristol has a large student population. It also has a higher than average percentage of qualified residents (35.1% in Bristol compared to 29.5% nationally). 20.2% of people travel to work on foot or by bike, whereas the national average is only 12.8%.
The census can therefore tell us a lot about local population characteristics.
|Bristol||England and Wales|
|Black and minority ethnic residents||13.9%||12.5% (England)|
|Average price of houses sold||£170,700||£163,100|
|Qualified NVQ4 or above||35.1%||29.5%|
|People who travel to work by public transport||13.5%||14.5%|
|People who travel to work either on foot or bicycle||20.2%||12.8%|
Source: Bristol City Council.
Population distribution means the pattern of where people live. World population distribution is uneven. Places which are sparsely populated contain few people. Places which are densely populated contain many people. Sparsely populated places tend to be difficult places to live. These are usually places with hostile environments e.g. Antarctica. Places which are densely populated are habitable environments e.g. Europe.
Population density is a measurement of the number of people in an area. It is an average number. Population density is calculated by dividing the number of people by area. Population density is usually shown as the number of people per square kilometer. The map below is a choropleth (shading) map and illustrates population density. The darker the colour the greater the population density.
Source: Columbia University's Center for International Earth Science Information Network
Page URL: http://sedac.ciesin.columbia.edu/plue/gpw/index.html?main.html&2
The map above shows that world population distribution is uneven. Some areas have a high population density while others have a low population density. Areas of high population density tend to be located between 20° and 60°N. This area contains a large land area and a relatively temperate climate.
Factors Affecting Population Density
There are a range of human and natural factors that affect population density. The tables below illustrate this.
(shape and height of land)
|Low land which is flat e.g. Ganges Valley in India||High land that is mountainous e.g. Himalayas|
|Resources||Areas rich in resources (e.g. coal, oil, wood, fishing etc.) tend to densely populated e.g. Western Europe||Areas with few resources tend to be sparsely populated e.g. The Sahel|
|Climate||Areas with temperate climates tend to be densely populated as there is enough rain and heat to grow crops e.g. UK||Areas with extreme climates of hot and cold tend to be sparsely populated e.g. the Sahara Desert|
|Political||Countries with stable governments tend to have a high population density e.g. Singapore||Unstable countries tend to have lower population densities as people migrate e.g. Afghanistan.|
|Social||Groups of people want to live close to each other for security e.g. USA||Other groups of people prefer to be isolated e.g. Scandinavians|
|Economic||Good job opportunities encourage high population densities, particularly in large cities in MEDCs and LEDCs around the world.||Limited job opportunities cause some areas to be sparsely populated e.g. Amazon Rainforest|
The world's population is growing very rapidly. In 1820 the world's population reached 1 billion. In 1990 it reached 6 billion people.
This rapid growth in population has been called a population explosion.
The major reason for population changes, whether in an individual country or for the whole world, is the change in birth and death rates. The birth rate is the number of live babies born in a year for every 1000 people in the total population. Death rates are number of people dying per 1000 people. When birth rates are higher than death rates the population of an area will increase.
Over the past 150 years improvements in health care and sanitation around the world have led to a drop in the death rate. While birth rates have dropped in MEDCs, birth rates are still high in LEDCs. Therefore the number of people in the world has grown rapidly.
Life expectancy is the average age a person can expect to live to in a particular area. Life expectancy can be used as an indicator of the overall 'health' of a country. From this figure you can determine many features of a country e.g. standard of living. As a general rule the higher the life expectancy the more healthy (or developed) a country is.
The Demographic Transition Model
The Demographic Transition Model attempts to show how population changes as a country develops.
The model is divided into four stages.
Birth rate and death rate are high - low natural increase - low total population
Birth rate is high - death rate is falling - high natural increase (population growth)
Falling birth rate - low death rate - high natural increase (population growth)
Birth rate and death rate is low - low natural increase - high total population
The Demographic Transition Model does not take into account migration.
Population Structure / Population Pyramids
The population structure for an area shows the number of males and females within different age groups in the population. This information is displayed as an age-sex or population pyramid. Population pyramids of LEDCs (Less Economically Developed Countries) typically have a wide base and a narrow top. This represents a high birth rate and high death rate. Population pyramids of MEDCs (More Economically Developed Countries) typically have a roughly equal distribution of population throughout the age groups. The top obviously gets narrower as a result of deaths. Population pyramids for every country in the world can be found here. Population pyramids are used to show the structure of the population according to age and sex. Click here to see the three major types of population pyramid.
The video below provides a really good explanation of population pyramids and discusses how the world's demography is changing