Abstract
Abstract. Urban boundary is an important indicator for urban sprawl analysis. However, methods of urban boundary extraction were inconsistent, and construction land or urban impervious surfaces was usually used to represent urban areas with coarse-resolution images, resulting in lower precision and incomparable urban boundary products. To solve above problems, a semi-automatic method of urban boundary extraction was proposed by using high-resolution image and geographic information data. Urban landscape and form characteristics, geographical knowledge were combined to generate a series of standardized rules for urban boundary extraction. Urban boundaries of China’s 31 provincial capitals in year 2000, 2005, 2010 and 2015 were extracted with above-mentioned method. Compared with other two open urban boundary products, accuracy of urban boundary in this study was the highest. Urban boundary, together with other thematic data, were integrated to measure and analyse urban sprawl. Results showed that China’s provincial capitals had undergone a rapid urbanization from year 2000 to 2015, with the area change from 6520 square kilometres to 12398 square kilometres. Urban area of provincial capital had a remarkable region difference and a high degree of concentration. Urban land became more intensive in general. Urban sprawl rate showed inharmonious with population growth rate. About sixty percent of the new urban areas came from cultivated land. The paper provided a consistent method of urban boundary extraction and urban sprawl measurement using high-resolution remote sensing images. The result of urban sprawl of China’s provincial capital provided valuable urbanization information for government and public.
Highlights
With the development of urbanization, more and more population reside in cities
Urban boundary product A came from the report ”East Asia's Changing Urban Landscape”, which was published by World Bank Organization(Bank, 2015)
Urban boundary product B came from the paper ”China’s urban expansion from 1990 to 2010 determined with satellite remote sensing”(Wang et al, 2012)
Summary
With the development of urbanization, more and more population reside in cities. Along with the rapid growth of urban populations comes rapid urban sprawl. Urbanization improves socioeconomic development and life quality, urbanization issues, such as blind expansion, faster land urbanization than population urbanization, extensive and inefficient use of construction land, unreasonable urban spatial morphology and structure, insufficient resource and environmental carrying capacity, become more and more serious, which results in enormous ecological and environmental challenges, such as heat island effect(Yuan and Bauer, 2007), local climate change(Stone et al, 2010), arable land loss(Tan et al, 2005), and water pollution(Yin et al, 2005). The urbanization of “population” can be represented by urbanization rate (ratio of urban population to total population), and the urbanization of “land” can be represented by non-agricultural urban area(Li et al, 2012). There are many image sources for urbanization monitoring(Griffiths and Hostert, 2010). With the increasing number of high-resolution satellites, many researchers used high-resolution images for automatic extraction of urban
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