Comparing spatial patterns of informal settlements between Nairobi and Dar es Salaam

Abstract

Currently, in many cities in the developing world, spatial data on informal settlements are generalized, outdated, or even non-existent. Moreover, there is a lack of comprehensive information about spatial factors that influence the location of informal settlements a cross different cities. These settlements continue to develop posing many urban challenges. This research employs locational and morphological parameters to measure and quantify the patterns of informal settlements using two example cities that is, Nairobi and Dar es Salaam. Remote sensing, GIS and spatial metrics are used to examine and explore the differences and commonalities of these settlements at three levels: landscape, settlement and object level. The patterns of the informal settlements were analysed at landscape, settlement and object levels. At landscape level, the roads, rivers, industries and market centres were used as input data to calculate accessibility of the settlements. In addition, the analysis of land use in the surrounding areas of such settlements was also carried out as well as the terrain analysis. At settlement level, the morphological aspects of the informal settlements were analysed using spatial metrics with the main focus on the size, shape, density and pattern of the informal settlements. At object level, the building characteristics were analysed: the size, shape, pattern and inter-building distances. Furthermore, four aspects of road network were analysed i.e. the density, circuitry, complexity and connectivity. This was done using graph theory. The results obtained demonstrate that the locational and morphological patterns in Nairobi INSEs are different from those in Dar es Salaam INSEs. The road accessibility in the settlements in Nairobi is higher than in Dar es Salaam. The dominant land use in the environs of informal settlement is residential land use. The morphological results indicate that Nairobi settlements cover smaller area and are more fragmented compared to those in Dar es Salaam. The building characteristics also differ as the mean building size in Nairobi is higher compared to Dar es Salaam. The distance between buildings is shorter in Nairobi compared to the buildings in Dar es Salaam settlements. In addition, the building shapes are rectangular in both cities with mean shape index of 1.25. The road connectivity results shows that Dar es Salaam settlements are more connected than those in Nairobi. In conclusion, there is a direct substantial relationship between road connectivity and road density in informal settlement areas in both cities.