| Urban renewal has been an essential strategy for urban development in China.The decision to redevelop land in the process of urban renewal will help to optimize urban spatial layout,guide functional positioning,and improve the physical environment,to solve the urban land resource shortage problem and achieve sustainable development.This research aims to simulate the dynamic trend of land-use change by using the Cellular Automata(CA)model;with various complex settings,the actual urban renewal status,as well as three scenarios for future development,are simulated and analysed in the case study of Chongqing to assist and support stakeholders in making proper decisions for future urban planning.The study proposes a method to embed the rent gap theory,which states that when the value gap between the potential ground rent and actual ground rent is larger,the attractiveness of investing capital in land redevelopment is larger.In the process of CA simulation,the rent gap theory,as a transition rules of land-use change,can reflect the internal mechanism of urban development.When the location-based spatial characteristics are used,the macro-economic factors,such as GDP,interest rate and depreciation rates,can quantify the rent gap in the CA model.In addition,based on the background of China’s "government-led" development,combined with the real situation,the endogenous and exogenous influencing factors of the policy are used as the quantitative factors of the rent gap theory and the transition rule of land evolution,respectively,which can accurately reflect the urban development.The results show that the dynamics in the land redevelopment of Chongqing are well described by the model;additionally,the policy implications to manage the urban renewal are discussed in the research.The conclusions are as follows.(1)The use of urban development and evolution models can help us understand the characteristics of land-use change and the internal mechanism of urban evolution,and help us to formulate urban plans scientifically,realize optimal allocation of land resources,and ensure the sustainable development of social economy.The CA model embedded in the rent gap theory and combined with government-led development proposed in this paper provides an effective research method for describing and explaining the evolution process and internal mechanism of urban land.It is valuable to simulate the future urban pattern and analyze the impact of policies on urban development,which can help decision-makers to formulate urban development plans.Urban managers can use the model to simulate land evolution,rationally plan existing stock resources,guide urban renewal,and create incremental value for socio-economic development.(2)Simulate the land-use changes in the urban area of Chongqing from 2011 to2016,and compare the results with the actual situation.The overall accuracy reaches92.29%,indicating that the simulation results truly reflect the status of urban land development.CA simulation can effectively reflect the mechanism of land-use change in Chongqing.It shows that it is meaningful to study urban land-use change using rent gap theory,location-based spatial characteristics,macroeconomic factors and policy conditions related to urban development.(3)This study is based on the best-fit set of parameters in land-use change of Chongqing in 2011-2016,combined with urban economic,industrial,ecological development and policy planning directions,assuming three scenarios of natural development,government-designated development,ecological protection,and extrapolating the simulation of the future in 2020 and 2025.The results show that scenario 1 presents the trend of inner city renewal,and gradually expands from the center.The center of construction shifts to north and west.The development trend of Scenario 2 is consistent with the trend of Scenario 1,but the development is faster,indicating that reasonable policy guidance and economic incentive measures can create a good environment for urban growth.Compared with the first two development scenarios,scenario 3 pays more attention to the importance of ecology to urban sustainability in addition to considering capital gains.The results show that the urban sprawl phenomenon has been significantly controlled.(4)The case of Chongqing shows that investors always search for the land with the largest rent gap for development to maximize the benefits,which confirms the scientific nature that “urban development is determined by the market and its capital operation”.However,excessive market behaviour often leads to the abnormal evolution of urban development,thus accelerating social-spatial differentiation.Therefore,government intervention is required to ensure orderly and stable changes in urban land use and to achieve fair distribution of social resources.While pursuing the land fiscal revenue,urban managers should rationally adjust the layout structure of urban land use,improve land use efficiency,and make it adapt to the urban form and specific development needs.Second,the government should rationally plan existing stock resources,guide urban renewal,and create incremental value for socio-economic development.At the same time,city governors should pay attention to improving urban public service facilities and urban landscapes,considering the fairness of the rent gap distribution,and the conservation of natural resources as well. |
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