The effects of urban expansion on spatial and socioeconomic patterns of the peri-urban areas: a case study of Isfahan city, Iran
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Date
2017
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Abstract
Although urban areas cover a very small fraction of the world’s land surface, rapid urban expansion has significantly changed the landscape and formed immense environmental and social impacts. These effects are principally important in rapidly changing areas such as urban settlements in developing countries.
Over the last decades, several studies have focused on the field of urban expansion. However, the implications of this rapid urban expansion have not been sufficiently analyzed. They presented some major challenges. Although most developed countries have comprehensive land cover information, the relative lack of geospatial data sets is a serious and real problem in the developing countries. Moreover, the analysis of urban expansion suffers from a general lack of knowledge and understanding of physical and socioeconomic factors. With this in mind, the main objective of the dissertation is to develop an effective methodology for identifying and addressing significant spatial and socioeconomic patterns to support effective management and program planning towards a sustainable urban development. Isfahan city in Iran is introduced as the case study.
In order to achieve this aim, it is necessary to quantify the spatial and temporal dynamics of urban expansion which often requires spatial analysis. A combination of remotely sensed (RS) data and geographic information systems (GIS) technologies could provide an eminently suitable means of assessing urban planning.
Methodologically, the study proposed adopting a research paradigm that integrates spectral indexes (i.e., modified normalized difference water index (MNDWI), soil adjusted vegetation index (SAVI), and urban index (UI)) and the classification approach. This method was proposed to reduce seven bands of an original Landsat image into three thematic-oriented bands. The next step was to analyze the growth of the expansion ratio in Isfahan between 1990 and 2010. Two main indexes were applied to quantify the urban expansion, including urban expansion differentiation index (UEDI) and urban expansion intensity index (UEII). Furthermore, a set of spatial metrics was developed to quantify the urban spatial patterns. The study also developed a core set of quantitative variables to characterize socioeconomic form. Three quantitative variables were developed to measure three dimensions of socioeconomic patterns: the intensity of physical activity, the degree that activities are evenly distributed, and the extent that high-density sub-areas are clustered.
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The results indicate that Isfahan city was characterized by significant rapid urban expansion, particularly over the first decade. The analysis of spatial patterns demonstrates that the city experienced phenomenal aggregated pattern in the central zones, leapfrogging pattern in the peripheral areas, as well as nodal and linear pattern in the middle regions of Isfahan city over the period considered. Through the adoption of socioeconomic measures, it is confirmed that local sprawl (discontinuity and strip development) was the dominant socioeconomic patterns of Isfahan city over 20 years. In other words, a sprawling pattern (job-based and population-based) was assured by the low value of the density and Moran coefficient, as well as the high score of Gini coefficient.
Geographically weighted regression (GWR) was suggested to explore the effects of urban expansion on the spatial patterns. The results generated from GWR indicate that patterns of urban expansion were affected by the intensification of the urban expansion in Isfahan city. In contrast, urban expansion had a significant positive relationship with the aggregation pattern in the central zones of the city. Moreover, to investigate the effects of urban expansion on the socioeconomic patterns, the Pearson correlation was applied. The results show that the expansion of the urban areas in Isfahan led to the decrease in density of population an employment, the increase of concentration in some districts, and the decrease of clustering. Overall, two obtained outcomes show that the city experienced a sprawling pattern over 20 years.
Making our cities more pleasant to live in is one of the main strategies being implemented as part of the national environment policy, which prioritizes maintaining a balance between urban expansion and protection of the environment and natural sites. In the case of Isfahan city, If the current expansion continues in the future, the new urban areas could develop in the fringe and rural areas and, therefore, the conflict between rapid urban expansion and limited land resource becomes more apparent.
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Keywords
Spacial patterns, Urban expansion, Socioeconomic patterns