Transcript incremental increase method

POPULATION
FORECASTING
INCREMENTAL
INCREASE METHOD
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Presented by Group 5:
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SEECHURN Ashivan (ID no. 1013779)
BHOODHOO Pranesh Singh (ID no. 1016842)
JUGGURNATH Bhuveenesh (ID no. 1011316)
MUTTY Yagnesh (ID no. 1010926)
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GOOLAB Muhafeez Mohammad (ID no. 1012799)
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SEWDINE Deepin (ID no. 1012426)
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TABLE OF
CONTENTS:
 Introduction
 Factors affecting changes in population
 Population Forecasting
 Incremental Increase Method
 Example
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INTRODUCTION
The design of waste water treatment plant and sanitation scheme is based on
the projected population of a particular area, estimated for the design
period. Any underestimated value will make the system inadequate for the
intended purpose while overestimation will make it costly.
As over the years the population of the area is ever changing, the system
should be designed by considering of the population at the end of the design
period.
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FACTORS AFFECTING CHANGES
IN POPULATION:
 Birth rate (causes an increase)
 Death rate (causes a decrease)
 Migration (causes either an increase or a decrease)
 Annexation (causes an increase)
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POPULATION FORECASTING
After collecting the present and past population record for the
area (from census population records), the population at the end of
design period can be predicted using various methods by considering
the growth pattern of the concerned area.
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INCREMENTAL INCREASE METHOD
This method is a modification of the arithmetical increase method and it is
suitable for an average size town under normal condition where the growth
rate is found to be in increasing order.
While adopting this method the increase in increment is considered for
calculating future population.
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INCREMENTAL INCREASE METHOD
The incremental increase is determined for each decade from the
past population and the average value is added to the present
population along with the average rate of increase.
Hence, population after nth decade is given by
𝑃𝑛 = 𝑃 + 𝑛 ∙ 𝑋 +
𝑛 𝑛+1
2
∙𝑌
Where,
𝑃𝑛 = Population after 𝑛𝑡ℎ decade
𝑋 = Average increase
𝑌 = Incremental increase
𝑃 = Actual population
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EXAMPLE:
Predict the population for the year 2021, 2031, and 2041
from the following population data using the incremental
increase method.
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YEAR
POPULATION
1961
860,741
1971
989,726
1981
1,201,897
1991
1,689,890
2001
2,079,270
2011
2,601,071
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SOLUTION
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YEAR
POPULATION
INCREASE (X)
INCREMENTAL
INCREASE (Y)
1961
860,741
-
-
1971
989,726
128,985
-
1981
1,201,897
212,171
+ 83,186
1991
1,689,890
484,993
+ 272,822
2001
2,079,270
389,380
- 95,613
2011
2,601,071
521,801
+ 132,421
TOTAL
1,737,330
273,816
AVERAGE
347,466
54,763
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SOLUTION
For year 2021:
𝑃1 = 2,601,071 + 1 × 347466 +
1 1+1
2
∙ 54,763 = 3,003,300
𝑃2 = 2,601,071 + 2 × 347466 +
2 2+1
2
∙ 54,763 = 3,460,292
𝑃3 = 2,601,071 + 3 × 347466 +
3 3+1
2
∙ 54,763 = 3,972,047
For year 2031:
For year 2041:
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