Basic term in population and population theory and how it is calculated.

2. Population.

3. Topics
• Development of Habitat patterns Environmental factors
governing settlement
• Population and Pollution
• Reasons for Over Population
• Production of Food
• Population Growth Demographic Projections

4. Environmental Factors Governing
Settlement
• The environment has considerably affected human being right
from his evolution. The environment effects human in many
ways. The environment has affected humans settlements in
many ways. The main factors which affect the distribution of
population and human settlement are
• 1) Relief of a land
• 2)Food
• 3) Water Resources
• 4) Energy Resources
• 5) Forest Resources
• 6) Shelter
• Environment plays an Important role in deciding population
distribution, density, settlement type and patterns.

5. POPULATION
• POPULATION may be defined as a group of organisms of the
same species occupying a particular space.
• OVER POPULATION: Over population is a condition when an
organism number exceeds the carrying capacity of its habitat.
• Over population is not a function of size or density it is
determined using the ratio of population to available resources.
• In simple words, it could be defined as increase in birth
rates and decrease in death rates.

6.  Population change = (Births + Immigration) –
(Deaths + Emigration).

7. Already India is containing 17.5%of the world’s population.The
current rate of population growth in India is 1.2% and the total
fertility rate is 2.1%.

9. Population Prediction

10. Over Population

11. Reasons for Over Population
• Increase in birth rate
• Decrease in death rate
• Better medical facilities
• Increase Immigration
• Decrease in Emigration
• Illiteracy

12. • Increase in birth rate: Birth rate
is the no of child born /1000
people/year. With the advent of
better medical facility, economic
prosperity, social beliefs the birth
rate increases which causes
increase in population
• Decrease in Death Rate: Death
rate is expressed in units of
deaths/ 1000 persons/year. The
development of technologies has
resulted in decrease in death rate.
Good and clean atmosphere,
sufficient nutrients, better medial
facility has provided longer and
healthy life.

13. • Better Medical facility: New
inventions of medicines, awareness
towards better health and control of
various diseases like TB, Small pox,
cancer, has resulted in increase of
population
• Increase Immigration: The countries
like USA where the development had
brought good environment for
citizens to stay, earn , and enjoy had
resulted in increase in immigration
• Decrease Emigration: In case of
Developing Countries the basic
requirement of citizens like peace,
development opportunities are
satisfied hence migration is avoided
this may cause over population

14. • Illiteracy: Due to some social beliefs, lack of knowledge towards
family planning, desire for male child are some of the factors
which causes increase in population

15. Population Explosion

16. • Population Explosion a sudden, large
increase in the size of a population.
• population crash A population crash is
a sudden decline in the numbers of
individual members in a population.

17. POPULATION EXPLOSION
• Effects of Population explosion
• Over use of natural resources
• Increase in Food Demand
• Increase in waste generation
• Other effects like
• Unemployment
• Poverty
• Increase in crime rate
• Energy crisis
• Over crowding of cities
• Pollution

18. POPULATION GROWTH
• Population growth is the change in population overtime and can
be quantified as the change in number of individuals in a
population per unit time of measurement
• According to population clock every second on an average 4-5
children's are born, and 2 persons die, thus resulting increase is
of 2.5 persons every second. That means every hour there is a
growth of 9000 persons and in one day population increase is of
the order of 2,14,000
• Current Population of India in 2012 - 1,170,938,000
(1.17,938 billion)

20. Other Factor for Population growth
Fertility Migration
Sex Ratio Age Group

21. Effect of population Growth

23. Control of Population growth
• Education: Literacy plays a major role in
checking population growth. Improving
the literacy rate particularly in woman,
can help in population control
• Incentives: Certain Incentives in the form
of government benefits, scholarships, to
children, subsidies, exemptions from tax,
promotion In jobs, should be offered

24. • Government Benefits: The government benefits should be
allowed only for those having smaller families.
• Publicity: The Importance of birth control methods for family
planning, the significance of small families and related
information should be published through various media, schools,
books, and other sources.

26. Population Forecasting
• To Design various infrastructures facilities like water supply
scheme, sewage disposal unit, the basic record of current
population and future population is must
• Therefore an estimate of future population is necessary for
designing this facilities.

27. Various Population Forecasting
• Arithmetic Increase method
• Geometric Increase method
• Incremental Increase method
• Decrease rate of growth method
• Graphical extension method
• Graphical Comparison Method

28. Arithmetic Increase Method
• This method is based on the assumption that population
increase at a constant rate
• Thus future population is given as
• Pn= Po + n X
• Where,
• P n= Future population
• P o= Population at present
• n= No of decades between now and future
• X= average of population increase
• This method of population forecasting is used for large cities
which have reached their saturation population

30. Geometric Increase Method
In this method per decade percentage increase or
growth rate is assumed to be constant and the increase
is compounded over the existing population every
decade.
Where,
• Pn= Future Population
• Po= Initial Population
• r= rate of growth
• N= no of decades

32. Incremental Increase Method
• In this method per decade growth rate is not assumed to be
constant as in the arithmetic or geometric increase method but
it is progressively increased or decreased depending on past
data
• P n= Po + n X +
• P n= Future Population
• P o= Initial Population
• X= Average increase in population
• Y= Average of Incremental Increase
• n= no of decades

34. Decrease rate of Growth Method
• Since the growth rate of Increase in population goes on reducing
as the cities reach their saturation, a method which makes use of
decrease in the percentage increase, is many a times used. In
this method, average decrease in the percentage increase is
found out and is then subtracted from the latest percentage
increase for each successive decades. This method is however
applicable only in cases, where the growth rate shows a
downward trend.

35. Simple Graphical Method
• In this method a graph is plotted from the available data
between time and population. The curve is then extended
smoothly up to the desired year. This method however
gives very approx results

36. Comparative Graphical Method
• In this method, Cities having Condition and characteristics
similar to cities whose future population is to be predicted are
first of all selected. It is then assumed that the city under
consideration will develop, as the selected city has developed in
past. This method has logical background and if statics of similar
cities are available vary precise readings can be obtained.

37. Population Theories
• There are three important theories of population, which are of
relevance to the present trends of population growth. The
theories are
• Malthusian Theory of population growth
• Marxian Theory

38. Malthusian Theory of maximum population
• English economist and demographer Dr. Robert Malthus gave
this theory, according to this theory
• In his first Proposition Population if unchecked, increases at a
faster geometric rate (i.e. 1,2,4,8,16…) whereas the food supply
grow at an arithmetic rate (i.e. 1,2,4,6,8…) . The necessary effect
of these two different rate of increase will be striking as after
sometime the population will outgrow the food supply and
people will starve and undergo misery.

39. • In the second preposition Malthus suggests that the food is
essential for the survival of the man and that the size of
population is determined by availability of the food. Greater is
the production of food larger the size of population which can be
sustained, this result Less production per capita. This will
ultimately lead to a situation where the number of people will
out weight the food production and the population will plunge
into starvation & misery.
• In the third proposition, Malthus concludes that the tendency of
the population

40. Population grows in quick
geometric progression
(2,4,8,16,32)
Food supply grows in
slow arithmetic
progression
(2,4,6,8,10)
Imbalance between population and food supply
Corrective measure of imbalance
Positive
checks
Preventive
checks
Malthusian Theory of population

41. Limitation of theory
• (a) Malthus did not consider migration of people
• (b) Malthus failed to recognise the potential of
human population to increase food supply
• (c) He also did not consider man ability to use
science and technology, advancement in food
production, and medical facility.
• (d) He proposed some preventive checks like
delay in marriage, abortion, and celibacy to check
population growth rather than suggesting its
implementation.

42. The Marxian Theory
of Population
• This is the modern theory of population, propagated by modern
economist such as Sidewide, Cannon, Dalton, and Robbins
• Optimum means the best or the ideal. Optimum population
means the ideal population or the ideal number of population
the nation should have relative to the natural resources, stock of
capital investment and state of technology. In other words,
optimum population is that size of population at which the per
capita output is the highest.

43. • A country is said to be under-populated if the population is less
than the optimum and over-populated if it is more than the
optimum. Initially population is small relative to availability of
resources hence due to specialization and efficient use of
resources per-capita output/ income increases to a maximum.
This size of population is the optimum population.
• Beyond this point, if population increases, the country will
become over populated and per capita output will start
decreasing. Overpopulation leads to low living standards,
frustration and unemployment
• Both under and overpopulation have short comings . It is the
optimum population which is best suited for a country. The
optimum population is not static number as it keep on changing
with discovery of new resources and technological
developments.

44. • The theory is further explained graphically, by plotting size of
population on X- Axis and per capita output on y-axis
P
R
Q
A
Per
Capita/Income
Population Size
P: Under population
Q: Optimum Population
R: Over Population

45. Population growth rate measurement

46. On mathematical based population
growth of two types
• Exponential growth rate
• logistic growth rate

47. Population Dynamics
• Population Dynamics is the study of Change in population.
• The basic Equation of Population Dynamics
• The rate of change in the size of population (N), in the course of
time, is the function of population size (N) itself. i.e. the rate of
change of N is the function of N

48. Where,
•
𝑑𝑁
𝑑𝑡
= Rate of change of N with time ‘t’
• r= Instantaneous rate of increase
• N= The size of Population

49. The Exponential Growth
• In exponential growth, a population's per
capita (per individual) growth rate stays the same
regardless of population size, making the
population grow faster and faster as it gets larger.
• the rate of the growth becomes faster as time
passes. This model assumes growth is not limited
by resources, predation, geographical space, or
other variables.
• When the per capita rate of increase (r) takes the
same positive value regardless of the population
size, then we get exponential growth.
• Exponential growth produces a J-shaped curve

50. The Exponential Growth
• The basic equation of population Dynamics,
relates the Increase with the population size itself, but doesn’t
establish a relation between population at two different
times, i.e. who to calculate Nt, population after time ‘t’ in
years
• Therefore Integrating eq
•
• Leads to Nt=No.ert

51. The Exponential Growth
• In case of Exponential growth, the rate of change of population is
directly proportional to the size of population at that time.
• If in a specified time ‘t’ the population size be Nt the population
growth or rate of change of population can be expressed as

52. 𝒅𝑵 𝒕
𝒅𝒕
⍺ 𝑵 𝒕
𝒅𝑁𝑡
𝑑𝑡
= 𝑅 𝑁𝑡
𝑑𝑁𝑡
𝑁𝑡
= 𝑅 𝑑𝑡
𝑑𝑁𝑡
𝑁𝑡
= 𝑅𝑑𝑡
ln Nt = Rt + Z ( R & Z are Constants)
When t=0, the initial size of pollution is ‘No’ i.e.
Nt= No

53. Thus,
ln No= R.0+ Z -------------I
Z= ln No
Now, putting value of Z in eq I,
ln Nt= Rt + ln No
ln Nt - ln No= Rt
ln
𝑁𝑡
𝑁 𝑜
= 𝑅𝑡
𝑁𝑡
𝑁 𝑜
= 𝑒 𝑅𝑡
Nt = No e Rt

54. Logistic Growth Rate
• In logistic growth, a population's per
capita growth rate gets smaller and smaller as
population size approaches a maximum imposed
by limited resources in the environment, known
as the carrying capacity (K).
• occurs when resources are limited thereby
setting maximum number of individuals that an
environment can maintain. The rate of growth
slows over time because resources are limited.
• When the per capita rate of increase (r)
decreases as the population increases towards a
maximum limit, then we get logistic growth.
• logistic growth produces an S-shaped curve.

55. exponential growth and logistic growth

57. • Demographic Projections/Transitions
– Demography definition,
• “The scientific and statistical study of human population is called
Demography.” It deals with
– Changes in population (either growth or decline)
– Composition of population (age group)
– Distribution of population (birth, death, migration, aging)
– Demography transition
• “If birth and death rates were equal, a zero population growth rate
would result which is called DEMOGRAPHIC TRANSITION.”
Demographic Projection

58. The Demographic Transition theory or
Demographic projection
• This Method is used to represent the process of shift from high
birth rates and death rates to low birth rates and death rates as
a part of the economical development of a country from a pre-
industrial to an industrialized economy. It is based on an
interpretation begun in 1929 by American demographer Warren
Thomson who observed changes in birth and death rates in
industrialized society over the past 200 years.

59. • This method represents that there is a relationship between the
population change and industrial growth with time.
• Stage 1 In pre-industrial society , death rates and birth rates
were both high and fluctuated rapidly accordingly to natural
events, such as droughts, and diseases, to produce a relatively
constant and young population
• Stage 2 In developing countries the death rate drops rapidly due
to improvement in food supply and sanitation, which increases
life span and reduces diseases, basic health care units and the
countries in this stage experiences great increase in population
• Stage 3 In this stage birth rate falls due to increase in status and
education of women, increase in parental investments.
Population growth begins to level off.
• Stage 4 There are both low birth rates and low death rates. Birth
rate has dropped due to change and life style and due to medical
advances and death rate has dropped too. As a result total
population is high and stable.

60. • Stage 5 This stage represents developed countries where
population are now reproducing well below their replacement
level. And the population growth may tend to be zero or
negative.

61. Population pyramids are graphics that
show information about the age and
gender of people in a specific country.
1) Pre-reproductive age group (o to 14
years)
2) Reproductive age group (15-44
years)
3) Post reproductive age group (45
years and above)
Population pyramids

62. Types of population pyramids
32

63. How do population pyramids
help us learn about
population?

64. Male Female
Population in millions
In this
country
there is a
high Birth
Rate
There is
also a high
Death
Rate.
This population pyramid is typical of
countries in poorer parts of the world.
Expanding pyramid

65. In some country the
government is
encouraging couples to
have smaller families.
This means the birth
rate has fallen.

66. Male Female
Population in millions
In this
country the
number of
people in each
age group is
about the
same.
The largest
category of
people were
born about
40 years
ago.
In this country there is a low Birth Rate
and a low Death Rate.
This population pyramid is typical of
countries in the richer parts of the world
Stationary pyramid

67. Population in millions
Male Female
In this
country the
birth rate is
decreasing.
In the future the
elderly people will make
up the largest section
of the population in this
country.
This is happening
more and more in
many of the world’s
richer countries.
Contracting pyramid

68. To sum up…
Expanding
pyramid
Stationary
pyramid
Contracting
pyramid
LESS DEVELOPED
COUNTRIES
DEVELOPING
COUNTRIES
DEVELOPED
COUNTRIES