Urban Spatial Growth and Land Use Change in Riyadh: Comparing Spectral Angle Mapping and Band Ratioing Techniques

The analysis of land use and land cover change is one of the steps in assessing spatial and environmental impacts of urban growth to foster urban sustainability. It is important to use accurate techniques and also to relate the result with theories of urban growth for effective urban growth management. This paper explores the use of a band ratio technique for land use change analysis and the linkage of the result with urban growth theory. The study uses multi-date and multisource satellite images to analyse the changing pattern of urban growth and land use change in Riyadh from 1972 to 2005. Two different techniques; - spectral angle mapping (SAM) and band ratioing - are applied for land use classification, also to compare the discrimination efficiency of these techniques in this arid environment. The classified images of different years are compared to analyse the changes in land use and spatial pattern of urban growth. Accuracies of classification results from SAM and ratioing methods are compared to ascertain the most suitable method for the land cover classification in this arid environment. The result indicates that the band ratioing method can be used to discriminate land features especially if a suitable threshold is used. However, the performance is not as promising as the SAM method in discriminating between vegetation and agricultural land. The land use analysis results indicate that urban growth management strategies in Riyadh have not been totally successful and the growth pattern corroborates the urban theory of diffusion and coalescence.