Land use/land cover change and its influence on land surface temperature in Hawassa, Ethiopia

Abstract Rapid urbanization and land-use change in many African secondary cities are intensifying land surface warming, with profound implications for human health, ecosystem integrity, and local climate regulation. Hawassa, one of Ethiopia's fastest-growing cities, has experienced rapid expansion of built-up areas and degradation of vegetated and wetland ecosystems. Yet, quantitative evidence on how these transformations affect land surface temperature (LST) remains limited. This study investigates the impacts of long-term land-use/land-cover (LU/LC) change on LST in Hawassa, Ethiopia, using multi-temporal Landsat imagery from 1988, 2008, and 2023. Supervised classification with a Support Vector Machine (SVM) algorithm was applied to derive LU/LC maps, while NDVI, NDBI, and LST were computed to assess vegetation dynamics, urban expansion, and thermal responses. The results show substantial landscape transformation over the 35 years: cropland remained dominant but decreased from 42.8% to 30.4%, settlements nearly doubled from 2.5% to 5.0%, and woody vegetation increased from 13.0% to 20.2%. Vegetation condition improved between 1988 and 2008 but declined by 2023, as indicated by NDVI trends, whereas NDBI increased continuously, reflecting the steady expansion of impervious surfaces. LST exhibited a clear warning signal, with cropland mean temperatures rising from 33.8 °C to 37.9 °C and grassland mean temperatures rising from 25.1 °C to 30.9 °C. At the same time, forests, wetlands, and water bodies consistently acted as cooling zones. Strong negative correlations between NDVI and LST and positive correlations between NDBI and LST confirm the cooling role of vegetation and the heat-amplifying effect of built-up areas. These findings highlight the need to integrate green infrastructure, protect wetlands and forests, and adopt climate-sensitive urban planning to mitigate surface urban heat island effects and support sustainable development in rapidly growing secondary cities such as Hawassa.