基于NPP-VIIRS夜间灯光数据的广西西江流域城市扩张时空格局演变研究

Spatiotemporal Evolution of Urban Expansion in GuangxiXijiang River Basin Based on NPP-VIIRS Nighttime LightsData

基于2012年、2014年、2016年、2018年、2020年的年度NPP-VIIRS夜间灯光数据,运用统计数据比较法提取广西西江流域城市建成区,并计算城市建成区的扩张速度、扩张强度指数、平均灯光强度指数、紧凑度指数、城市中心迁移距离、角度和速度,分析2012—2020年广西西江流域城市扩张动态变化情况。结果表明:1)统计数据比较法的平均总体分类精度在97%以上,能精确反映西江流域城市建成区发展的实际情况。2)2012—2020年广西西江流域城市建成区平均扩张速度为4.61 km^(2)/a,呈现先快速发展后减缓的扩张趋势。扩张强度与平均灯光强度的变化趋势与扩张速度基本保持一致。3)广西西江流域城市建成区整体的紧凑度和分形维数均呈现降低的趋势,说明广西西江流域城市扩张较为平衡,存在内部建设和外部扩张两种扩张发展形式。4)2012—2020年河池市与南宁市因城市发展建设使城市中心迁移距离较大,其余各市的城市中心迁移距离平缓,稳定扩张;各城市中心迁移速度与城市中心迁移距离和方向的发展情况基本保持一致。

Based on the NPP-VIIRS nighttime lighting data for five annual periods of 2012,2014,2016,2018 and 2020,this paper uses the statistical data comparison method to extract the urban built-up areas in Guangxi Xijiang River Basin and calculates the expansion rate,expansion intensity index,average lighting intensity index,compactness index,urban center migration distance,angle and speed of urban built-up areas to analyze the dynamic changes of urban expansion in Guangxi Xijiang River Basin from^(2)012 to 2020.The results show that 1)the average overall classification accuracy of the statistical data comparison method is above 97%,which can accurately reflect the actual development of urban built-up areas in the Xijiang River basin.2)the average expansion speed of urban built-up areas in the Xijiang River basin of Guangxi from^(2)012 to 2020 is 4.61 km^(2)/a,showing an expansion trend of rapid development first and then slowing down.The changing trend of expansion intensity and average light intensity is basically consistent with the expansion speed.3)The overall compactness and fractal dimension of urban built-up areas in the Xijiang basin of Guangxi show a decreasing trend,indicating that the urban expansion in Guangxi Xijiang Basin is more balanced,and there are two forms of expansion development,internal construction,and external expansion.4)From^(2)012 to 2020,Hechi city and Nanning city make urban centers due to urban development and construction migration distance is larger,while the urban centers of the remaining cities have a flat migration distance and stable expansion;the migration speed of each urban center remains basically consistent with the development of urban center migration distance and direction.