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Analysis of Population Distribution and Filtering Processes of the city of Colombo, Sri Lanka Using GIS
L Manawadu
Senior Lecturer
University of Colombo,
Sri Lanka
Email: manawadu@ait.ac.th, lasan_m@webmail.cmb.ac.lk
Abstract
The population distribution of a city changes over time and sometime it helps to mark out some specific incidents happened in past with increasing of the population in the city. This pattern may reveal the population filtering process operating within the city. An understanding of the population distribution changes and its historical development is useful for formulating development strategies in a city.
To study the spatial changes of population, the gross population density were adopted (Refer as: Arithmetic Density or man-land ratio) which is number of persons per unit of land is used. Even though it has inherited limitations, it helps to understand certain characteristics. To identify the filtering process, time series data has been analyzed from the first official census, which held in 1871 to the latest census in 2001.
The Burgher’s concentric zone Model (1926) has been tested from the point of view of residential distribution pattern in the city of Colombo. In this analysis, population has been transformed to the concentric circles conception from the city center. To examine the filtering and spatial changes of the distribution of population, concentric circles were adopted from 1871 to 2001.
To examine the relationships, population concentration has been correlated with some other factors such as ethnic groups; occupational groups, land use and land cover etc. To overcome the main technical constraint in this analysis; changes of boundaries (City limits and ward boundaries) data has been transformed to a 0.5km. grid and statistical analysis has been carried out based on the cell values.
The results indicated that the high population concentration circle, which was located near the Central Business District (CBD) of the city, has been shifted to the next ring. The grid analysis revealed that there is a significant relationship between population concentration and the ethnic groups. Moors and Tamils and tending to be resided in highly population concentrated areas.
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