INCREMENTAL INCREASE METHOD 1

INCREMENTAL INCREASE

METHOD23/03/2013

POPULATION FORECASTING

INCREMENTAL INCREASE METHOD 2

Presented by Group 5:

o SEECHURN Ashivan (ID no. 1013779)

o BHOODHOO Pranesh Singh (ID no. 1016842)

o JUGGURNATH Bhuveenesh (ID no. 1011316)

o MUTTY Yagnesh (ID no. 1010926)

o GOOLAB Muhafeez Mohammad (ID no. 1012799)o SEWDINE Deepin (ID no. 1012426)

23/03/2013

INCREMENTAL INCREASE METHOD 3

TABLE OF CONTENTS: Introduction Factors affecting changes in population Population Forecasting Incremental Increase Method Example

23/03/2013

INCREMENTAL INCREASE METHOD 4

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.

23/03/2013

INCREMENTAL INCREASE METHOD 5

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)

23/03/2013

INCREMENTAL INCREASE METHOD 6

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.

23/03/2013

INCREMENTAL INCREASE METHOD 7

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.

23/03/2013

INCREMENTAL INCREASE METHOD 8

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

Where,

= Population after decade

= Average increase

= Incremental increase

= Actual population23/03/2013

𝑃𝑛=𝑃+𝑛 ∙𝑋+{𝑛 (𝑛+1 )2 }∙𝑌

INCREMENTAL INCREASE METHOD 9

EXAMPLE:Predict the population for the year 2021, 2031, and 2041 from the following population data using the incremental increase method.

23/03/2013

YEAR POPULATION

1961 860,741

1971 989,726

1981 1,201,897

1991 1,689,890

2001 2,079,270

2011 2,601,071

INCREMENTAL INCREASE METHOD 10

SOLUTIONYEAR 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

23/03/2013

INCREMENTAL INCREASE METHOD 11

For year 2021:

For year 2031:

For year 2041:

23/03/2013

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

SOLUTION