How urbanisation alters the intensity of the urban heat island in a tropical African city

Abstract

Due to the combined effects of urban growth and climate change, rapid urbanisation is particularly challenging in African cities. Areas that will house a large proportion of the urban population in the future coincide with where natural hazards are expected to occur, and where hazard risk management institutions, knowledge, and capacity are often lacking. One of the challenges posed by rapid urbanisation is the Urban Heat Island (UHI) effect, whereby urban areas are warmer than the surrounding rural areas. This study investigates urbanisation patterns and alterations in surface UHI (SUHI) intensity for the Kampala urban cluster, Uganda. Analyses show that between 1995 and 2017, Kampala underwent extensive changes to its urban built-up area. From the centre of the city to adjoining non-built up areas in all directions, the urban land cover increased from 12,133 ha in 1995 to 25,389 ha in 2016. The area of SUHI intensity in Kampala expanded significantly over the 15-year period of study, expanding from 22,910 ha in 2003 to 27,900 ha in 2016, while the annual daytime SUHI of 2.2°C in 2003 had decreased to 1.9°C by 2017. Although SUHI intensity decreased in some parts of the city, elsewhere it increased, suggesting that urbanisation does not always lead to a deterioration of environmental conditions. We postulate that urban development may therefore not necessarily create an undesirable impact on local climate if it is properly managed. Rapidly growing cities in Africa and elsewhere should ensure that the dynamics of their development are directed towards mitigating potentially harmful environmental impacts, such as UHI effect through careful planning that considers both bluespaces and greenspaces.

Spatio-temporal development of the urban heat island in a socioeconomically diverse tropical city

“…It is typically thought that UHIs increase in magnitude as a city increases in size and population (Li et al 2017;Zhou et al 2017;Mentaschi et al 2022), though this effect is smaller in tropical cities (Manoli et al 2019). We found that UHIs in long-urbanised areas in Makassar have remained stable since at least the 1990s, in line well-researched cities such as London (Jones & Lister 2009), but have expanded into recently urbanised areas, following patterns observed across Europe (Trusilova et al 2009) and Africa (Li et al 2021). Patterns of UHI development in recently urbanised areas varied with urban land use.…”

“…We found that UHIs in long-urbanised areas in Makassar have remained stable since at least the 1990s, in line well-researched cities such as London (Jones & Lister 2009), but have expanded into recently urbanised areas, following patterns observed across Europe (Trusilova et al . 2009) and Africa (Li et al . 2021).…”

“…The basis for such mitigation is the development of an explicit, localised understanding of the spatial and temporal patterns of UHI exposure, and the likely impacts thereof in rapidly growing cities and their associated informal settlements (Deilami et al 2018;Nagendra et al 2018). By understanding trends in urban development and UHIs, the potential for spatial expansion and intensification of UHIs with continued urbanisation can be projected (Li et al 2021). In turn, this understanding of spatiotemporal trends can be integrated into context-specific mitigation strategies.…”

“…2018). By understanding trends in urban development and UHIs, the potential for spatial expansion and intensification of UHIs with continued urbanisation can be projected (Li et al . 2021).…”

Geospatial Effect on the Mining Operation in Joda/Barbil Area of Odisha, India

“…Hasty vicissitudes in the LULC of an area have turn out to be a major environmental distress in recent times (Imran et al, 2021 [26], Li X., 2021 [29]). This has commanded untenable development with the drop of green corridor along with variations in local climate and creation of urban heat islands (UHI's) (Guha et al, 2017 [30]).…”