Remote sensing of urban growth and landscape pattern changes in response to the expansion of Chongming Island in Shanghai,China |
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| Authors: | Guangrong Shen Nasser Ibrahim Abdoul Yun Zhu Zijun Wang Jianhua Gong |
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| Institution: | 1. School of Agriculture and Biology and Research Centre for Low-Carbon Agriculture, Shanghai Jiao Tong University, Shanghai, P.R. China;2. Key Laboratory of Urban Agriculture (South), Ministry of Agriculture, Shanghai, P.R. China;3. Zhejiang-Cas Application Center for Geoinformatics, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Jiashan, P.R. China;4. Shanghai Urban Forest Research Station, State Forestry Bureau, Shanghai, P.R. China |
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| Abstract: | Chongming Island in China is currently undergoing a rapid urbanization and an increasing environmental pressure due to its fast-paced social economic development. Owing to natural silts deposit phenomenon as well as artificial land reclamation practices, the Island is also experiencing an expansion phenomenon. The synergy between these natural and artificial phenomena results in a rapidly changing landscape on Chongming Island. Consequently, the tools and methods for a rapid and cost-effective detection and assessment of related issues are urgently needed to ensure a harmonious and sustainable development of the Island. We herein investigate the urban growth and the landscape pattern change in relation to the Island’s expansion phenomenon and the associated complexity of land use/cover change. Our investigation is based on a time series of Landsat satellite images spanning the past 34 years. The methodological approach adopted in the present study combines vegetation indices, images textural features and social statistics data in an object-oriented classification framework. With Chongming Island expanding by an annual rate of 0.9% between 1979 and 2013, we found that the proportion of vegetation area to the total area decreased from 71 to 45%, whereas the proportion of built-up area to the total area increased from 5 to 19.9%. The urban area expanded about six times from 1979 to 2013, and during the same period, the Island’s population did not change significantly. The urban spatial expansion of Chongming Island caused distinct expansion intensity index for each intervals, and significant fragmentation and diversity in the landscape pattern between 1979 and 2013. It was also found that the rapid urbanization process took place at the expense of landscape pattern changes at any time within the study period. This is a strong indication that besides the natural geographic element, economic development and policy orientation were the dominant driving factors. If the current rate of urban expansion is to be maintained and the vegetation cover is to keep decreasing at an annual rate of 0.1% (period 1979–2013), their combined effects would profoundly alter the ecological environment in the long term. These findings provide a basic objective and scientific information for knowledgeable decision-making and policy formulation regarding regional planning and management to ensure harmonious transition of Chongming towards ecologically oriented development. |
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| Keywords: | Urbanization index object-oriented classification Chongming Island pattern metrics landscape change |
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