Sharma Richa, Chakraborty Anusheema, Joshi Pawan Kumar
Department of Natural Resources, TERI University, New Delhi, 110070, India,
Environ Monit Assess. 2015 Jan;187(1):4206. doi: 10.1007/s10661-014-4206-7. Epub 2014 Dec 12.
Over the past five decades, the fragile wetland ecosystem surrounding the city of Kolkata has witnessed extensive changes in the name of urban development. In this study, we elaborate relationships among biophysical parameters and land surface temperature (LST) in Kolkata city and nearby surrounding areas where rapid urbanization has occurred. LST and associated surface physical characteristics were assessed using Landsat images acquired for the years 1989, 2006, and 2010. The satellite data was used to study the spatiotemporal urban footprint and correlation among normalized difference vegetation index (NDVI), normalized difference built-up index (NDBI), normalized difference water index (NDWI) and LST. Land use land cover (LULC) maps prepared using supervised classification had overall accuracy of 90, 88, and 86 % and kappa coefficient of 0.8726, 0.8455, and 0.8212 for 1989, 2006, and 2010, respectively. The spatial expansion as a consequence of increasing urban population is 108.94 km(2) over past two decades. The urban built-up in and around the city extends up to 88.71 km(2) in 1989, 144.64 km(2) in 2006, and 197.65 km(2) in 2010. These changes have attributed in elevating surface temperature in the study region. Analysis of biophysical parameters shows LST and NDBI having a positive correlation, LST and NDVI having negative correlation, while NDBI and NDWI having a perfectly negative correlation. Satellite estimated temperatures of the surface show a warming trend evident from increasing mean surface temperature values from 27.36 °C in 1989 to 30.025 °C in 2006 and 33.023 °C in 2010. The magnitude and extent of the estimates of LST are consistent with the urbanization pattern throughout the city and adjoining areas.
在过去的五十年里，加尔各答市周边脆弱的湿地生态系统见证了以城市发展之名发生的广泛变化。在本研究中，我们阐述了加尔各答市及其周边快速城市化地区生物物理参数与地表温度（LST）之间的关系。利用1989年、2006年和2010年获取的陆地卫星图像评估了地表温度及相关的地表物理特征。卫星数据用于研究时空城市足迹以及归一化植被指数（NDVI）、归一化建筑指数（NDBI）、归一化水体指数（NDWI）与地表温度之间的相关性。使用监督分类法编制的土地利用土地覆盖（LULC）图在1989年、2006年和2010年的总体精度分别为90%、88%和86%，kappa系数分别为0.8726、0.8455和0.8212。过去二十年中，城市人口增加导致的空间扩张面积达108.94平方公里。1989年城市及其周边的建成区面积为88.71平方公里，2006年为144.64平方公里，2010年为197.65平方公里。这些变化导致了研究区域地表温度升高。生物物理参数分析表明，地表温度与归一化建筑指数呈正相关，与归一化植被指数呈负相关，而归一化建筑指数与归一化水体指数呈完全负相关。卫星估算的地表温度呈现出变暖趋势，平均地表温度值从1989年的27.36℃上升到2006年的30.025℃，2010年为33.023℃，这一趋势十分明显。地表温度估算的幅度和范围与整个城市及毗邻地区的城市化模式一致。
