基于生态空间胁迫的大都市区增长情景模拟

The formation and growth of urban agglomerations have turned to be one of the main urbanization mode in China. New urbanization strategy issued by central government also gives specific attention to smart urban growth especially in rising urban agglomerations. How to select the optimized spatial pattern of urban growth for urban agglomerations becomes one of the most important parts in new urbanization planning. Cellular automata (CA) have proven to be efficient in modeling urban expansion and they have been widely applied to the simulation of urban growth in many cities. The simulation results derived from CA have also provided scientific references for making land use planning. This study established a modeling framework based on a constrained CA model to simulate the urban expansion with the consideration of ecological stress effect and it is oriented to the concept of building "ecological city in future ". The constraints of both ecological sensitivity and urban development suitability were incorporated into the urban growth modeling. Three main kinds of growth scenarios including the chaotic edge extension, the restrained expansion for ecological-conservation and the coordinated growth pattern were designed and discussed. The visual and quantitative comparison was further carried out to detect a plausible growth pattern for decision-making in land use planning. The three major indices including construction suitability, ecological security and landscape compactness were used to measure the rationality of the three designed scenarios, quantitatively. Meanwhile, urban agglomerations in the middle reach of the Yangtze River have turned to be the fourth growth pole in China, and Nanchang metropolitan area has become one of the most important development nodes of this growth pole. In recent years, Nanchang metropolitan area has experienced rapid urbanization, which has resulted in a series of ecological problems. Selecting an optimized spatial pattern is important and attractive to direct the future smart urban growth of Nanchang metropolitan area. Therefore, this study selected Nanchang metropolitan area as a case study area to analyze the rationality of the growth patterns. The results indicated that the coordinate growth scenario can meet the demands of both urban expansion and ecological conservation in Nanchang metropolitan area. The simulation pattern under this scenario can greatly reduce ecological stress effect from urban growth and also generate the highest total value of the selected three indices in 2049. The coordinate growth scenario can be used as a scientific reference for making spatial planning of Nanchang metropolitan area such as delimiting urban growth boundaries. This study also indicated that urban growth modeling incorporated with ecological stress effect can provide an efficient tool for decision-making in urban land use planning.