Abstract
Cairo city, being the Egypt’s industrial and cultural center, has a problem of rapid urban sprawl. The city has an extremely high population density which is continuously increasing through informal settlements that grow by sprawling due to migration from the Nile Delta villages and the high population growth rates. The present study attempts to understand, detect and quantify the spatial pattern of Cairo’s urban sprawl using Shannon’s entropy and multi-temporal Landsat TM and ETM images acquired for the period from 1984 to 2013. Supervised classification was applied to extract the built-up areas and to measure the changes in the urban land-use class among the city wards. Shannon’s entropy was applied to model the city’s urban sprawl, trend and spatial change. The entropy values for the city’s electoral wards were modeled and used in an interpolation function to create an entropy surface (index) for each acquired temporal image. Such index indicates the spatial pattern of the urban sprawl and provides a visual comparison of the entropy phenomenon in such wards. Results indicate that Shannon’s entropy index increased from (1.4615) in year 1984 to (2.1023) in year 2013, indicating more dispersed urban growth, a sign of urban sprawl. The maximum entropy values are found in the eastern wards namely El Nozha, Awal Nasr District, Thany Nasr-District, El Salam, El Marg and El Bassatein. A regression analysis was carried for the population growth rate and the built-up areas. Findings help in understanding the sprawl patterns and dynamics among Cairo’s electoral wards and provide a visual comparison. The applied methodology provides explanations and facilitates tracing and measuring the urban sprawl which is needed by decision makers and city planners of mega cities.
Highlights
The term urban sprawl refers to the excessive and uncontrolled expansion of urban areas, which causes a wide range of social and environmental problems and has become a major concern for urban planners and policy makers in the developed and developing world (Brueckner, 2000 [1]; Frenkel and Ashkenazi, 2007 [2]; Knaap et al, 2013[3])
Pocas et al (2011) [9] used three different temporal satellite images of the same area and find out the different types of vegetation, barren/fellow lands and used land and used landscape matrices to characterize the spatial heterogeneity, fragmentation and complexity of the landscape. From these studies it is clear that remote sensing and geographical information system (GIS) may be used as useful tool to study the urban sprawl as it decrease the cost of data generation and saves time
The main objective of the current study is to examine the dynamic phenomenon of urban sprawl/growth and pattern in the highly populated city of Cairo
Summary
The term urban sprawl refers to the excessive and uncontrolled expansion of urban areas, which causes a wide range of social and environmental problems and has become a major concern for urban planners and policy makers in the developed and developing world (Brueckner, 2000 [1]; Frenkel and Ashkenazi, 2007 [2]; Knaap et al, 2013[3]). Their study shows that together with remote sensing, geographic information systems and photogrammetric techniques, built-up concentration can be identified and quantified from time series of aerial photographs and satellite images This facility can assist in monitoring the growth of built-up areas and in drafting measures and policies to address urban sprawl’s imminent effects. Pocas et al (2011) [9] used three different temporal satellite images of the same area and find out the different types of vegetation, barren/fellow lands and used land and used landscape matrices to characterize the spatial heterogeneity, fragmentation and complexity of the landscape From these studies it is clear that remote sensing and GIS may be used as useful tool to study the urban sprawl as it decrease the cost of data generation and saves time
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