Transcript Document
Demographic Transition Model Stage 1 - High Fluctuating Birth Rate and Death rate are both high. Population growth is slow and fluctuating. Reasons Birth Rate is high as a result of: Lack of family planning High Infant Mortality Rate: putting babies in the 'bank' Need for workers in agriculture Religious beliefs Children as economic assets Death Rate is high because of: High levels of disease Famine Lack of clean water and sanitation Lack of health care War Competition for food from predators such as rats Lack of education Typical of Britain in the 18th century and some tribes today. Stage 2 - Early Expanding Birth Rate remains high. Death Rate is falling. Population begins to rise steadily. Reasons Death Rate is falling as a result of: Improved health care (e.g. Smallpox vaccine) Improved hygiene (Water for drinking boiled) Improved sanitation Improved food production and storage Improved transport for food Decreased Infant Mortality Rates Typical of Britain in 19th century; Bangladesh; Nigeria today Stage 3 - Late Expanding Birth Rate starts to fall. Death Rate continues to fall. Population rising. Reasons: Family planning available Lower Infant Mortality Rate Increased mechanization reduces need for workers Increased standard of living Changing status of women Typical of Britain in late 19th and early 20th century; China; Brazil today Stage 4 - Low Fluctuating Birth Rate and Death Rate both low. Population steady. Typical of USA; Sweden; Britain today Life expectancy The number of years that a child born in a particular country in a certain year can expect to live. Fertility rate The average number of births per woman. Infant mortality The proportion of children who die before they reach the age of one year (sometimes before the age of five). Population structure This refers to the age and sex distribution of the population. Population Dependency Ratio Population Dependency Ratio Countries with rapid population growth Countries with Rapid Population Growth When a country's population grows quickly it has the following effects • The large number of young people have to have services e.g. schools provided for them • There are fewer older people, so less money needs to be spent on them • There is a relatively small proportion of adults of working age; these people provide the wealth for the services • There is pressure on the countryside with the extra population to feed; this can result in overgrazing, over cropping and soil erosion • People move to the cities to find work; developing countries with rapidly growing populations have the fastest growing cities in the world • Shanty towns grow up on the edge of cities; these are self-constructed buildings of poor quality which can lack vital services such as water, electricity and sanitation • Some people apply to migrate to developed countries in order to improve their standard of living Population pyramids 1 Pyramid : Here the base is very wide indicating a very high birth rate. The width drops off very quickly. This means people must be dying. Very few reach old age. Few countries are still in this stage today but some rainforest populations would display this pattern. Implications: Clear need for investment into water supplies, health care, food supplies and housing to reduce death rates. Population pyramid for Mozambique 2000 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. 2 Pyramid : Still a large base so high birth rate but also a wider and taller pyramid as more people are living to older ages. This is stage two of the demographic transition model and includes many countries in Africa such as Kenya. Implication: Probable need to invest in education about family planning to reduce birth rate. Possibly indicates that women are undervalued in society so this could be tackled. matches stage 2. Projected population pyramid for Mozambique 2025 In the second graph, the largest group in Mozambique in 2025 is still the 0-4 age group, but there are nearly as many people in the 5-29 age groups. Now the population pyramid matches stage 2. 3 Pyramid : Note the more ‘domed’ shape. It means many people are living to older ages as quality of life improves. There are also proportionately fewer births. This is stage three of the demographic transition model. Chile would be a good example. Implication: As the population becomes increasingly older there may be a need to invest in facilities and services for them. Still a need for continued investment in family planning. 4 Pyramid : Very small base due to the very low birth rates and death rates displayed in the wide top. This would be representative of Australia that has recently come through stage three of the demographic transition model. Implication: Should the situation continue there are serious implications about providing for the elderly population (increasing cost of health care, state pensions) especially as the working population becomes proportionally smaller. This is a major concern in much of the developed world. Population pyramid for the UK 2000 Notice how in the UK 2000 pyramid there is a bulge in the area of the 30-34 and 35-39 age groups, with the numbers thereafter reducing fairly steadily as the ages increase. This matches stage 4 of the demographic transition model. Projected population pyramid for the UK 2025 Compare this to the 2025 pyramid, which would be stage 5 in the model. Here the bulge extends much further, covering the age groups 30-64, with the numbers beginning to reduce significantly only after 64. Concave profile Convex profile Population pyramids can also be influenced by: Migration: Likelihood of extra young males as these are likely to migrate. Famines: Clear drops in population especially among the very young as these are most likely to suffer. War: Clear drop off in male populations of fighting age.