Urban heat island and level of thermal comfort : A quest of Peri-Urban Siliguri

The peri-urban area is defined as the area adjacent of the urban jurisdiction. These areas often go through tremendous change in terms of new developmental activities. Peri-urban areas are the result of thegrowing demand of land. The dynamics of land surface temperature change and formation of heat island has attracted scientists’ attention in the recent past. The heat island zones are areas where the surface temperature is higher than the adjoining places. Researchers have found that this situation results in unbalanced thermal comfort for a citiy. Therefore, cities like Siliguri which is rapidly expanding outwards has been investigated at peri-urban level for studying the land surface temperature (LST). A buffer of 10 km from the administrative boundary of the city has been incorporated. The satellites images were compared to get the variation in the land use land cover (LULC) and the impact of the LST changes. The Indices like Urban Heat Island (UHI), Urban Hotspot (UHS), and Urban Thermal Field Variance Index (UTFVI) were prepared for 1991 and 2023 to analyse the difference in urban heat island and level of thermal comfort in the study area. The built-up area increased from 4.11 % to 12.10 % in a span of 23 years in the study area. The minimum land surface temperature for 1991 was recorded as -1.45°C which has increased to 3°C in 2023. The maximum land surface temperature for 1991 was recorded as 3.25°C which has increased to 10.25°C in 2023. The mosaic of UHS and UHI combined and clipped with LULC layer depicts that 41 % of the UHS and UHI is under built-up area, followed by agricultural land (29 %) and fallow land (14 %). The Geographically Weighted Regression (GWR) map shows a trend of more developed UHI areas in the south eastern part of the study area. The R² result shows significant explanation of independent variable (LULC type from vegetation to built-up) on the dependent variable (LST). It has been found that development of infra structure and resultantformation of heat island areas align with the six level thermal comfort zonation in the Peri-Urban Siliguri.