Study on Temporal and Spatial Characteristics of Fuzhou Built-Up Area Based on Remote Sensing Data of Nighttime Light

It is of great significance to grasp the spatio-temporal characteristics and expansion mechanism of urban built-up areas for formulating urban development strategy. This paper takes the built-up area of Fuzhou as the study area, uses multi-temporal Landsat images and remote sensing data of nighttime light (NTL) as the main data sources, and extracts the built-up area of NTL images with a higher spatial resolution comparison method. It discusses the development trends of the Fuzhou built-up area from 2000 to 2021 from the perspectives of temporal and spatial evolution characteristics and spatial morphology evolution and analyzes the relationship between population factors, economic factors, natural conditions, policy factors, and urban expansion. The results show that the urbanization level of Fuzhou is gradually improving, and the compounded nighttime light index (CNLI) increases from 0.0105 in 2000 to 0.0635 in 2021. The trend of expansion speed and expansion intensity is consistent, showing the changing trend of first fast and then slow, then accelerating and then slowing down. The expansion direction presents the trend of "expanding eastward, advancing southward and expanding westward", the spatial form tends to be irregular, and the migration range of the center of gravity is not significant. Population factors, economic factors, and expansion are positively correlated and closely related, and natural conditions and policy guidance affect the direction and mode of the expansion of the built-up area. The above results indicate that the overall urban development of Fuzhou shows an upward trend, which is consistent with the planned urbanization development trend of Fuzhou.