An integrated index to assess urban sprawl case study-Kaluthara city and its suburbs

Abstract

The previous works on the subject of urban sprawl showed that urban sprawl is a complex phenomenon but they have not identified a clear definition of what exactly urban sprawl really is. Assessing urban sprawl is even a more difficult task even though there are numerous attempts that have been made to assess urban sprawl. Different scientific methods and approaches were used for this task. Some researchers have attempted to assess urban sprawl in a simple manner while some attempted multi dimensional approaches such as multi factor approach, integrated urban sprawl approach, geo-spatial approach etc. The problem is that these assessment methods are not appropriate in the Sri Lankan context, because most of them address urban sprawl as experienced in the Western world. Therefore, this research attempted to fill this gap by identifying a suitable method for assessing urban sprawl in Sri Lanka. It is noteworthy that, this is the first attempt for assessing urban sprawl in Sri Lankan context as surveys of previous studies indicate. Generally speaking urban sprawl in Sri Lanka is on the increase. But it has not yet been empirically assessed or calculated in detail. Major cause that influenced urban sprawl in Sri Lanka was the rapid urban expansion. It may be that this might have been encouraged by not having a proper definition of "urban" applicable to the country. Under these circumstances and the present phase of development, the research identified a multi-factor approach to assess urban sprawl in Sri Lanka. For this purpose 12 indicators have been selected which have been associated with urban sprawl, viz. urban built up density, residential population density, leapfrog development, strip highway development, loss of arable land, encroachment of open space, damage s to eco sensitive areas, segregated land use, proximity to urban functions, availability of local area development plans, land values and road density. Combining all these indicators in a rational weighted manner the research formed an Integrated Urban Sprawl Index (IUSI) for assessing urban sprawl in Sri Lanka. Land use changes which have been taken place in between 1992 and 2002, highlighted the gradual increase of urban expansion of the selected area. For instance, by 2002, some rubber plantation areas are completely converted into residential purposes. Further, it is found that the low land values of these areas are directly influenced for land conversion. The validity of the formulated IUSI was tested in ground situation of 2002 in the city of Kalutara and its suburbs. For this purpose, GIS techniques such as mapping, modeling and overlaying; photo interpretation, spread sheets, Graphs and word processing were applied to analysis urban sprawl in Sri Lanka. VII Finally, the urban sprawl assessment in Sri Lanka carried out in two ways; (1) Urban sprawl assessing by individual component and (2) urban sprawl assessing by IUSI. The results of individual component analysis illustrated four clusters of urban sprawl that can be identified in the area such as highly compact, compact, sprawling and highly sprawling while the integrated urban sprawl index revealed only three types of development patterns such as highly compacted, compacted and sprawling areas.