Spatial expansion and spatial-temporal evolution characteristics of main urban area of Zhengzhou based on remote sensing
To monitor the spatial and temporal evolution of the built-up area and promote the urban planning and construction and high-quality development of Zhengzhou City,six periods of Landsat images were selected to remotely monitor and characterize the spatial and temporal evolution of the spatial expansion of the main ur-ban area of Zhengzhou City from 1990 to 2020 by constructing an expert knowledge decision tree.The results show that:from 1990 to 2020,the built-up area of the main urban area of Zhengzhou City increased by 464.62 km2,and the speed and intensity of urban expansion went through two phases of rising and then decli-ning,and is still in a period of rapid expansion;affected by the planning and construction of functional new are-as,Zhengzhou City expands significantly in the direction of the due east and southeast,and urban development is mainly concentrated in Jinshui District in the east;the spatial expansion elasticity index(5.75)of the city during the study period is much higher than the reasonable level,which means that the utilization rate of urban land resources is not high.The results of the study objectively reveal the spatial expansion pattern of Zhengzhou City,which is of reference value for optimizing the spatial pattern of the land and improving the overall function of the city.