1. Urban Vulnerability Assessment Population Estimation
More Look at ‘RA Elective Element’ of ITC

2. Population Projection
Needed for planning purposes
Length of time in the future for projections
Short term (up to 10 years)
Long term (up to 50 years)
Both depend on past records

3. Population Forecasting
Model to estimate population
Direct Method
Indirect Methods

4. Direct Method

5. Methods for Estimation
Graphical methods
Extrapolation
Least squares regression
Mathematical methods
Assumes that population growth follows a mathematical relationship

7. Population Growth
Population growth is generally considered to be exponential
P=P0ert
where:
P = future size of the population at time t
P0 = current size of the population
t = number of years for the extrapolation
r = assumed constant rate for each of the t years
Reference: class notes of Dr. deMonsabert (GMU)

8. How to Calculate r?
The growth rate (r) is usually expressed as a fraction of the increase in population per year
Growth rate is also defined by the following equation:
r=(b-d)+(i-e)
where:
b = birth rate
d = death rate
i = immigration rate
e = emigration rate
net migration = i-e
Natural increase of population = b - d
Net migration= the rate with which people moving into a region minus the rate with which people leaving that region

9. Example:
The 2010 population in a town is surveyed and determined to be 50,000. What would you predict the population to be in the years 2020 if birth rate is 40 persons / 1000 people (or 4 %), death rate 15 persons / and net migration is 10 persons / 1000 people?

10. Doubling Time
Double time represents the length of time for the population to double in size when growing with a constant growth rate (r)
Tdb =70/r
where:
Tdb = the doubling time
r = the constant growth rate in %

11. Indirect Method Population estimate derived from:
Household counts and occupancy rate
School registered children
Residential area with population density
Roof Area Method
Total Population = Total roof area of all buildings/average roof area per person
What about informal settlements?
Sample survey can be done to calculate population density or average roof area per person.
Number of occupants vs. roof area can be plotted and trend line can be used for unplanned residential area.

12. Source of Data
Existing registers: Census data, cadastral data, taxation data
Existing maps: Topo maps, cadastral map
Field surveys
Satellite images/aerial photographs
DEM and DSM (deriving building heights)

13. Statistics Characteristics
Number of inhabitants
Densities
Age composition
Gender distribution
Etc.

14. Dynamic Characteristics
Population is dynamic in space and time
Activity pattern
Distribution in space
Distribution in time

15. Daily Human Activities
Source: Dr. Richard Sliuzas, ITC
Similar charts for ‘Presence of school children’ and ‘presence of house wives’ during day for different days of a week.
Hourly presence of people = # of house holds* (persons) + # of shops* (persons) +# of other units *(persons)