厦门城市不透水面及其热环境效应的遥感分析

Urban Impervious Surface and its Effects on Thermal Environments in Xiamen:An Analysis Based on Remote Sensing Technology

当前,城市空间的快速扩展使得原来以植被、水体为主的自然景观逐渐消失,取而代之的是以不透水面为主的人工建筑物,这一改变已对区域乃至全球的生态环境造成了显著的影响.本研究以海峡西岸中心城市——厦门市为研究区,以1989年、1996年和2009年的Landsat-5 TM影像为主要数据源,采用归一化差值不透水面指数(NDISI),研究了厦门市在这期间的不透水面分布的时空变化.结果发现,厦门市不透水面面积在这20年间扩展了近7倍,其增长主要占用了大面积的植被和水体.回归分析表明城市不透水面与地表温度呈明显的指数型正相关关系,而与植被、水体面积呈线性负相关关系.

The fast expansion of urban space has led to the substitution of natural vegetation and water dominated landscapes by impervious materials, imposing significant impacts on ecosystems at local and global scales. This study measured the development of impervious surface in Xiamen, a coastal area in subtropical China, and investigated its impacts on regional thermal environment. The Normalized Difference Impervious Surface Index （NDISI） was used to extract impervious surface features of the study area from Landsat Thematic Mapper images of 1989, 1996, and 2009, respectively. The results revealed that the area of impervious surface in Xiamen increased rapidly from 31.78 km2 to 246.54 km2 during the 20-year period, with an average annual growth rate of 10. 74%. This expan- sion mainly took the place of vegetation lands （ amounting to 77.29% ） and sea side areas （ amoun- ting to 20. 27% ）. Further quantitative analysis on the relationship between impervious surface and other components of the urban ecosystem suggested that the urban impervious surface area had a strong positive exponential relationship with the land surface temperature （LST） rather than a simple linear relationship. Multivariate statistics has proved that the expansion of urban impervious surface area was the most important factor contributing to the rise of urban LST, while vegetation and water worked in- versely.