Class 12 NCERT(Chapter 2) The World Population Distribution, Density and Growth

         THE WORLD POPULATION 

       Distribution ,Density and Growth

Introduction 

"The people of a country are its real wealth"

• The population of the world is unevenly distribute .
• The population of world also increasing.

"Asia has many places where people are few and few place where people are very many "

                                                                                                        George B. Cressey.

Patterns of population Distribution in the world 

• Patterns of population distribution and density help us to under stand the demographic characteristics of any area .
• The term population distribution refers to the people are spaced over the earth's surface .
• Broadly, 90 percent of the world population lives in about 10 percent of its land area .

Density of population 

It is defined as number of people living per square km area.

• Each unit of land has limited capacity to support people living on it.
• It is necessary to understand the ratio between the number of people to the size of land.
• It is usually measured in persons per square  km 

     Density of population  =  Population /Area 

Factors influencing the distribution of population 

1. Geographical factors.

a) Availability of water

• People prefer to live in  areas where fresh water is easily available.
• It is because of this that river valleys are among the most densely populated areas of the world.

b) landforms 

• People prefers living on flat plains and gentle slopes.
• Such areas are favorable for the production of crops and to build roads and industries.

c) Climate 

• An extreme, climate such as very hot or cold desert are uncomfortable for human habitation.
• Areas with a comfortable climate, where there is not much seasonal variation attract more people.
• Mediterranean regions were inhabited from early periods in history due to their pleasant climate .

d) soils

• Fertile soils are important for agricultural and allied activities
• Areas which have fertile loamy soils have more people living on them as these can support intensive agriculture .

 2. Economic factors 

a) Minerals 

• Areas with mineral deposits attract industries .
• Mining and industrial activities generate employment .

Example : Katanga Zambia copper belt in Africa .

b) Urbanization

• Cities offer better employment opportunities, educational and medical facilities , better means of transport and communication.
• Mega cities  of the world continue to attract large number of migrants every year.

c) Industrialization

• Industrial belts provide job opportunities and attract large numbers of people . 
• The Kobe- Osaka region of Japans thickly polluted because of the presence of a no of industries .

3. Social and cultural factors

• Some places attract more people because they have religious or culture significance.
• In the same way - people tend to move away from places where there is social and political unrest.

Population Growth .

1.Growth of population 

Change of population in particular area between two points of time is known as growth of population.

2.Growth rate of population 

This is the change of population expressed in percentage.

3.Natural Growth of population 

This is the population increased by difference between birth and deaths in a particular region between two points of time. 

4.Natural Growth = Births - Deaths
5.Actual Growth of population = Births-Deaths +Inmigration -Out migration .

6. Positive Growth of population 

When birth rate is more than the death rate between two points of time .

7.Negative Growth of population 

If the population decreases between two points of time it is known as negative growth of population 

It occurs when the birth rate falls bellow the death rate or people migrate to other countries .

Components of population change 

• There are three components of population change births , deaths and migration.

(CBR) The crude birth rate is expressed as number of live birth rate in a year per thousand of population.

It is calculates as:

    CBR =Bi/P X 100

Here, CBR =Crude birth rate ;Bi=live births during the year ;P=mid year population of the area .

(CDR)Crude death rate is a simple method of measuring mortality of any area. 

It is expressed in terms of numbers of deaths in a particular year per thousand of population in a particular region.

CDR is calculated as :

  CDR= D/PX100

Here; CDR= Crude death rate; D= Number of death ;P=estimated mid year population of that year.

Migration 

Movement of people from one place to another .

Place of origin

• When people move from one place to another , the place they move from is called the place of origin.
• The place of origin shows a decrease in population .

Place of Destination

• The place they move to is called the place of destination.
• The population increases in the place of destination.

Migration may be permanent, temporary or seasonal.

Immigration

Migrants who move into a new place are called immigrants .

Emigration 

Migrants who move out of a place are called emigrants .

The push factors 

This factors make the place of origin seem less attractive for reasons like unemployment, poor living conditions,  political turmoil, unpleasant climate, natural disasters, epidemics and socio- economic back wardens

The pull factors 

This factors make the place of destination seem more attractive than the place of origin for reasons like better job opportunities and living conditions, peace and stability security of life and property and pleasant climate.

Trends in population growth 

• The population on the earth is more than six billion .
• It has grown to this size over centuries .
• In the early periods population of the world grew very slowly.
• It is only during the last few hundred years that population has increased at an alarming rate 

Doubling time of world population 

• There is a great variation among regions in doubling their population
• Developed countries take more time to double their population as compared to developing countries 

Spatial pattern of population change 

Although the annual rate of population change (1.4%) seems to be low, it is actually not so.

This is because:

• When a small annual rate is applied to a very large population, it will lead to  a large population change.
• Even if the growth rate continues to decline  the total  population grows each year .

Impact of population change:

• A small increase in population is desirable in a growing economy.
• Population decline is also a matter of concern .

Demographic transition :

Demographic transition theory can be used to describe and predict the future population of any area. 

Three staged model of demographic transition theory.

First stage:

• It has high fertility and high mortality because people reproduce more to compensate for the deaths due to epidemics and variable  food supply. 
• The population growth is slow are most of the people are engaged in agriculture where large families are an asset. 

second stage :

• Fertility remains high in the beginning of second stage but it declines with time. 
• This is accompanied by reduced mortality rate.

Last stage :

• In the last stage both fertility and mortality decline considerably. 
• The population is either stable or grows slowly.

Population control measures: 

• Access to family planning service is a significant factor in limiting  population growth and improving women's health.