Changing nature of Land surface temperature and transformation of vegetation cover and water bodies in the 2nd largest urban agglomeration of West Bengal, Eastern India

Abstract

Land surface temperature (LST), vegetation and water are very crucial for maintaining a healthy urban ecosystem. Asansol is one of the fast growing urban industrial agglomerations of West Bengal in Eastern India. In the last few decades the city has experienced a rapid urban industrial expansion along with the population growth which is associated with the continuous increase of LST. Considering this the present study has been designed to explain the nature of LST changes and transformation of land cover over the last thirty years utilizing the Landsat imageries in GIS platforms. In this study changing nature of land surface temperature, vegetation cover and surface water bodies and their interrelationship over the last thirty years have been analysed. Landsat 5TM images of May and October for the year 1990, 2000 and 2010 and Landsat 8 OLI images of May and October for 2020 have been utilized in GIS platform. LST and different indices NDVI, MNDWI and NDBI have been extracted for analyzing the nature of change along with image classification. The results of the study depict that LST is increasing continuously. In the first decade (1990–2000) LST increased at 0.24 °C/year followed by an increasing rate of 0.33 °C/year in the second decade (2000–2010) and 0.37 °C/year in the last decade (2010–2020). Same trend is also perceived for built up area, where it increased at 0.96 km2/year, 1.71 km2/year, and 2.49 km2/year in corresponding decades. On the other hand, the vegetation cover is continuously decreasing (1.59 km2/year, 0.75 km2/year and 0.49 km2/year in consecutive decades) as well as the surface water bodies (0.62 km2/year in, 0.41 km2/year, and 0.25 km2/year in corresponding three decades) over the last thirty years. Correlation and regression analysis of land surface temperature and various indices shows positive relation between LST and NDBI, negative relation between LST and MNDWI, and also between LST and NDVI. Urban-industrial expansion is the important factor for increasing temperature and transforming vegetation and surface water bodies.