An assessment of land use/land cover changes and their impact on the urban heat island effect dynamics : a case of Kampala City

Abstract

Urbanization in African cities poses significant environmental challenges, including Urban Heat Island (UHI) effects. The accumulation of anthropogenic heat in cities exacerbates this issue, posing serious health risks to the public. This study investigates the UHI trends associated with LULC changes at a local scale, residents’ heat perceptions, and coping strategies to guide planning interventions for improved UHI mitigation and adaptation. The study employed a mixed-method research design. Quantitatively, Kampala’s landscape was classified into homogenous LULC zones based on thermal properties. The UHI trends were analyzed using LST data from Landsat imagery for the years 2005, 2014, and 2023, while LULC changes were assessed through change detection analysis. The relationship between UHI and LULC was examined using the ANOVA tests, boxplots, and grid analyses. Furthermore, local perceptions and behavioral responses were assessed through face-to-face interviews using closed-ended questionnaires and key informant interviews. Findings revealed an expansion of UHI-affected areas from 58% of Kampala city’s landscape in 2005 to 72% in 2023, driven by the observed increase in built-up areas and a decline in natural cover. The built-up LULC zones were associated with the highest UHI values, while natural cover zones had the lowest. The increase in UHI was significantly correlated with urban expansion, densification, and vertical enhancement. Compact high/mid-rise, compact low-rise, lightweight low-rise, and large low-rise zones experienced the highest UHI effects. Nakivubo I, Nakulabye I, Kamwokya II, and the civic center were selected for the heat perception and behavioral response survey. Most respondents (82%) perceived urban heat as increasing and greatly impacting their daily lives, but lacked awareness of its causes. Coping strategies included staying hydrated (81%) and using electric fans/air conditioners (21%), alongside opening windows, wearing light clothes, frequent bathing, and shading. Challenges encountered included increased electricity and water bills, water scarcity in the informal settlements, exposure to water-borne diseases, and limited space for greening. Based on the LULC zone, heat perceptions, and expert recommendations, the study proposes planning strategies for enhanced UHI adaptation and mitigation. Short-term strategies include public awareness campaigns and planning for cooling centers, while long-term measures focus on urban greening, increasing city albedo, and innovative building designs. These findings provide insights for urban planners, policy makers, and public health officials to foster a more resilient and sustainable Kampala city.