Spatial Monitoring of Urban Growth Using GIS and Remote Sensing: A Case Study of Nairobi Metropolitan Area, Kenya

Abstract

Nairobi city expanded spatially leading to the formation of the 32,514 km2 Nairobi Metropolitan Area. The region faces rapid urbanization challenges and lacks reliable data for urban planning. This study is aimed at monitoring the urban land cover using GIS and Remote Sensing techniques. Three different land cover maps produced at ten year epochs between 1995 and 2015 were used to evaluate and analyse urban growth visually and quantitatively. Spatial metrics indices and the Annual Urban Spatial Expansion Index were employed in the quantitative analyses. Urban land cover increased from 408.99 km2 to 763.79 km2 and to 2,187.82 km2 with annual growth rates of 8.4% and 17.2% in the two study period epochs. The areas had annual spatial expansion indices of 4.58% and 6.32% respectively in the periods 1995- 2000 and 2000-2015. Radial-axial expansion of built-up areas along transport routes led to the expansion of urban areas into agricultural and forest land. The region’s spatial plan forecasted an urban land cover of 1,717.72km2 by the year 2030, yet by the year 2015, the urban area was 2,187.82 km2. These growth characteristics will have an effect on the location of the proposed Cyber city, Knowledge-cum-Health city and the Aerotropolis, as proposed in the spatial planning concept of the NMR. The spatial analysis of the NMR growth trends could support in the urban growth management mechanisms and plans for sustainable development.