Urban climate stress assessment integrating spectral indices, Random Forest-based land use and land cover dynamics, and urban flood inundation using Google Earth Engine

With population growth and urban expansion, urban regions are experiencing environmental stress. Alterations in land use and land cover (LULC) directly affect surface temperature, runoff generation, microclimate, and ecological resilience. To measure the effects of surface heat, vegetation changes, urbanisation, and reductions in waterbodies, the Urban Environmental Stress Index (UESI) is estimated for the cities of Guwahati and Silchar in Assam, in the north-east of India. Both cities are flood-prone and are experiencing urban expansion and population growth. In the present study, spectral indices that characterize vegetation, temperature, waterbodies, built-up areas, and soil conditions in the two regions are derived for 2018, 2021, and 2024, along with flood-inundation and LULC maps. UESI is calculated using spectral indices and subsequently integrated with flood-inundation and LULC maps to analyse its spatial distribution. More than 75% of the area of Guwahati city falls within the moderate to very high UESI class. In Silchar, the area covered by high UESI zones accounts for 6.81%, 9.62%, and 11.29% of the area in 2018, 2021, and 2024, respectively. Areas having high UESI values were characterized by high LST, reduced vegetation, and degraded green spaces. In Guwahati, the flooded areas were concentrated in low- to moderate-UESI zones, and in Silchar, flood exposure was concentrated in both low and very high UESI zones. The present study shows that both cities are experiencing urban-induced environmental stress, and that integrated urban resilience planning to control urban sprawl, improve drainage systems, and restore wetlands and vegetation is urgently needed.