Investigating the impact of vegetation and built-up as determinants of land surface temperature change in the Varanasi Metropolitan Area of India

With approximately fifty percent of the world's population currently living in towns, urbanisation seems to be the distinct consequence across nations. The most prominent effects of Urbanization are the land use and land cover change from a natural landscape into a built-up landscape. Vegetation and open land are generally replaced with increasing impervious surfaces, which increases the Land Surface Temperature (LST), especially in dense urban areas like Varanasi.

Land surface temperature is an important parameter in understanding the Urban Heat Island (UHI) effect, which is the occurrence of warmer temperatures in urban areas compared to neighbouring suburban and rural areas. LST provides information on the physical features, such as climate and soil surface, as well as modifications in land use and human activities that impact the climate. While the presence of water-permeable surfaces and a surplus of vegetation lowers the level of land surface temperature (LST), human-induced heat discharges brought on by energy consumption and the expansion of land surface coverage by materials with high heat conductivity and capacities are the primary root causes of an increase in LST. Warmer temperatures produce greater transpiration and the reduction in soil moisture. It is therefore crucial for micro-climatic change studies to monitor and understand the spatial distribution of LSTs for comprehending LST landscape patterns across the globe.

The major components of studies in LST include Land cover, the Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Built-up index (NDBI). The correlation between the impacts of changes in vegetation and built-up on LST has been examined in this study by applying GIS statistical techniques on LANDSAT satellite data on a spatio-temporal scale. The study reveals that LST exhibits a positive correlation with built-up but a negative correlation with vegetation, and this relationship varies with variations in the nature of built-up and vegetation in the study area.

Keywords: Urbansiation, Land Surface Temperature (LST), Urban Heat Island (UHI), NDVI, NDBI, LULC, Climate, Micro-climate.