Spatiotemporal Impact of Urbanization on Urban Heat Island Using Landsat Imagery in Oran, Algeria: 1984–2024

Urbanization promotes urban infrastructure development and increases artificial impervious surfaces, leading to rising temperatures and urban climate alterations, contributing to the appearance and intensification of the Urban Heat Island (UHI). In this study, a 40-year time series of Landsat images of the city of Oran was used to generate two biophysical indices. The Normalized Difference Built-up Index (NDBI) distinguished built-up areas from non-built-up areas, while a semi-automatic classification produced Land Use/Land Cover (LULC) maps, for a precise analysis of urban sprawl. The results revealed a significant expansion of urban areas, with an increase of 65.28 km2 between 1984 and 2024. The Normalized Difference Vegetation Index (NDVI) was used to estimate Land Surface Temperature (LST) by applying the “Mono Window” algorithm for Thematic Mapper (TM) images and the “Split Window” algorithm for Enhanced Thematic Mapper (ETM+) and Operational Land Imager–Thermal Infrared Sensor (OLI–TIRS) images. The surface temperature difference between urban and rural areas increased from 0.36 °C in 1984 to 4.5 °C in 2024, highlighting the intensification of the Surface UHI (SUHI) effect. LST maps also helped to identify the areas most vulnerable to UHI, as well as those where this effect is persistent, corresponding to the Permanent UHI (PUHI).