O Level Notes : Geography - Settlement And Population - Population Growth

The study of population is called demography. It is important to understand different aspects of population because population is critical to development and exploitation of resources.

Thistopic focuses on factors affecting population growth, diseases affecting population, population policies, and migration.


The term population growth refers to an increase in the number of people living in an area , a country, state, town or a city. Population growth is an open system constituted by inputs, processes and outputs.

Population components


The growth rate for a period of time   such as   five to ten years is calculated   using this formula.However to find nthe annual percentage growth rate simply divide the growth rate for the ten years by the number of years as shown inthe example below.


The percent change from one period to another is calculated from the formula: Where:

PR = Percent Rate

V Present = Present or Future Value

V Past = Past or Present Value

The annual percentage growth rate is simply the percent growth divided by N, the number of years.


In the year 2017 the world population was growing at an annual rate of 1.11%. In that same year, Zimbabwe's population was growing at an annual rate of 2.5%. It should be noted that population growth rates are higher in developing countries than in developed countries due to several reasons like ineffective family planning methods, religious and cultural beliefs and low levels of mechanisation just but to mention a few.

Factors affecting population growth

Since population growth is a system, it is affected by several factors. Some of these factors include birth and death rates, migration and a county's level of development.


Births affects population growth since a country's population grows as a result of natural births occurring within a region or a country. Birth occurring has a direct link to other demographic aspects like fertility and national population policies. Fertility refers to a population's ability to reproduce. A region or a country with more woman in the child bearing age has a higher fertility rate than that with less women in the child bearing age.

Birth rate

The term birth rate refers to the number of live births per thousand per year of the population.

Birth rate or crude birth rate is calculated as:

Live birth per year X 1000

Total population


Fertility rate refers to the actual number of live children a women is expected to have during her reproductive years such as 15-49 years.

Mortality rates

Mortality rates refer to the death of people but has a bearing on population growth in the sense that high mortality rates decreases population growth whilst low mortality rates increases population growth. Death rate is the number of deaths per thousand per year. In 2012 census, Zimbabwe death rate was estimated at 21 deaths per thousand.

Crude death rate or death rate is calculated as:

Deaths per year X 1000

Total Population


Infant mortality

Infant mortality rates refers to the number of live born babies who die before reaching the age of one per thousand live births per year. An increase in mortality rates results in the decline in population growth.


Countries level of mechanisation

Mechanisation tends to have a bearing on the population growth of an area or region or country. Most of African countries still thrive on agro based economies hence they are in dire need of labour. If the country has a lower level of mechanisation, communities tend to bear more children to consume a steady and sufficient supply of labour in their fields. The birth of many children to ensure labour supply results in population growth.

Level of woman emancipation

Countries in which woman are regarded as second class citizens are often characterised by high population growth. This is the case because low levels of woman emancipation results in early marriages which results in higher fertility rate. In contrast, woman emancipation promotes late marriages thus a lower population growth.

Religious belief

Certain religious beliefs tend to result in population growth since they are pro large families. Most catholic communities are anti birth control measures whilst most apostolic churches promote polygamies. Such religious beliefs result in population growth due to large families.

Population growth in Zimbabwe

Zimbabwe's population shows that the system is not static since there has been considerable changes experienced in the 19th, 20th and 21st centuries. Prior to 1980, in the 60s and 70s, Zimbabwe was among most countries with high growth rates. This was mainly due to high birth rates caused by availability of many women in the child bearing age hence a higher fertility rate.













The changes in fertiliy rates in Zimbabwe from 1960 to 2002 are due to a number of factors which include improved access to contraceptives, emancipation of women, improved medication, and antinatalist population policy adopted by the government. These factors reduced the number of births per woman.