基于夜间灯光数据的环杭州湾城市扩张及植被变化

综合运用遥感与GIS技术,基于2000、2007和2013年的DMSP/OLS夜间灯光数据和MODIS NDVI数据,利用灯光阈值提取法、植被指数分析等方法,研究环杭州湾地区城市扩张和建成区植被变化特征.结果表明: 采用最佳阈值方法,能够实现对城市地区用地信息的有效提取;环杭州湾地区城市用地整体围绕杭州湾呈“V”型模式扩展,并表现出面状、线状和点状3种扩张模式;从城市扩张速度、动态度和形态紧凑度来看,各地级市表现出较大的时空差异,但整个研究区的城市扩张速度和动态度普遍呈现降低趋势,平均城市形态紧凑度则经历了先下降后上升的过程.各城市建成区的植被状况也存在显著差异,2000—2007年,除嘉兴市建成区植被状况变差外,其余各地级市建成区植被状况均变好;2007—2013年,所有城市建成区植被状况变差;2000—2013年,城市扩张对建成区植被均产生了不利影响.

Urban expansion and vegetation changes in Hangzhou Bay area using night-light data

Based on DMSP/OLS night-light data and MODIS NDVI data for 2000, 2007 and 2013, this paper studied on characteristics of urban expansion and vegetation changes in built-up areas with nighttime light threshold extraction and vegetation index analysis using remote sensing and GIS. Results showed that the threshold method could realize the effective extraction of urban land information. In general, the urban built-up area expanded along with Hangzhou Bay in V model, and there were three expansion patterns: polygon pattern, linear pattern and point pattern. Obvious spatio-temporal variations in different cities were found in the rate and the dynamic degree of urban expansion and the compactness of urban morphology. The whole study area showed a decreasing trend in the rate and the dynamic degree of urban expansion, while the average compactness of urban morphology declined after the rise. Vegetation conditions became better in built-up areas except Jiaxing in 2000-2007, but it became worse in all cities in 2007-2013. Urban expansion had a ne-gative effect on the vegetation change in built-up areas in 2000-2013.