Impact of Urbanization on Urban Heat Island Dynamics in Shillong City, India Using Google Earth Engine and CA-Markov Modeling

Abstract

Growth in urban areas contributes to environmental degradation through increased land surface temperature (LST), exacerbating the urban heat island (UHI) effect. This study examined how land use and land cover (LULC) characteristics of Shillong City are linked to the UHI phenomenon. The LULC was classified into five broad categories: agricultural land, barren land, settlement, vegetation, and water bodies. The results show that the study area experienced notable changes in the LULC pattern from 1993 to 2023, with settlement areas increasing by 10.96%, transforming previously barren lands. The emergence and growth of settlements (and/or built-up areas) and impervious surfaces have led to a steady increase in LST. The settlement land use class had an average LST of 17.45 °C in 1993, 21.56 °C in 2003, 21.37 °C in 2013, and 21.75 °C in 2023. From 1993 to 2023, surface temperatures in settlement areas rose by a maximum of 4.3 °C, while barren land and vegetated areas also saw an increase of 4.9 °C and 4.0 °C, respectively. The relationship between LULC and the LST has been evaluated to identify hotspot areas. The highest temperatures are found in crowded and dense built-up areas, while the lowest temperatures are found in vegetated areas and water bodies. The findings also reveal a clear warming trend over the 30-year period, marked by a substantial decrease in areas with LST below 12 °C and between 12–17 °C, highlighting a shift towards warmer temperatures. Projected LULC changes indicate that urban areas will experience significant growth, increasing from 17.36% of the total area in 2023 to 21.39% in 2030, and further to 28.56% by 2050. The results suggest that the settlement land use class will increase by 11.2%, accompanied by a decrease in agricultural lands, vegetation, and water bodies.