Multi-scenario simulation of urban land change in Shanghai by random forest and CA-Markov model

Abstract

The multi-scenario simulation of urban land can effectively reveal the characteristics and trends of changes in urban space and the contradictions of land use in urban sustainable development. By designing a model based on the random forest algorithm and CA-Markov model, we simulated the evolution of urban space in Shanghai from 2015 to 2030 under two distinct scenarios — unconstrained development and development with planning intervention. Results of model validation indicate that the model accurately simulates urban land in 2015. In Shanghai, important factors affecting urban development are population, GDP and distance to subways. Under the unconstrained scenario, urban areas in Shanghai are predicted to increase by 157.79 km2 between 2015 and 2030, and the spatial expansion of urban areas follows a concentric pattern. Meanwhile, under the scenario with planning intervention, urban expansion is at a lower speed, and more compact because of constraints of ecological, cultivated and cultural protection, and urban areas are predicted to increase by 95.46 km2 in 2030 compared with 2015. We observe a similar concentric pattern, although significantly smaller in magnitude, in spatial expansion under this scenario. The results show that urban development will be more sustainable under the constraints of ecological and cultivated protection.