Urban heat in Johannesburg and Ekurhuleni, South Africa: A meter-scale assessment and vulnerability analysis

Souverijns, Niels; Ridder, Koen De; Veldeman, Nele; Lefebre, Filip; Kusambiza-Kiingi, Frederick; Memela, Wetu; Jones, Nicholas K.W.

doi:10.1016/j.uclim.2022.101331

Cited by 15 publications

(12 citation statements)

References 71 publications

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“…All measurements were executed by local community participants. Practices on how to involve and engage the local community in measurement campaigns and generate awareness for climate change research are described in Souverijns et al (2022). The main goal of these campaigns were two‐fold.…”

Section: Methodsmentioning

confidence: 99%

High resolution heat stress over a Sahelian city: Present and future impact assessment and urban green effectiveness

Souverijns,

De Ridder,

Takacs

et al. 2023

Intl Journal of Climatology

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Cities in the Sahel are heavily impacted by heat stress. Climate change, growing population rates and urbanization will increase the magnitude and intensity of urban heat stress towards the future. This study provides a comprehensive analysis of the current status of heat stress in Niamey (Niger) and future impacts by combining the results of two models operating at city‐level: UrbClim which simulates (future) climate and GeoDynamiX, providing future city spatial extents combined with the results of a measurement campaign. Additionally, a meter‐scale assessment of heat stress within the city is executed for a selection of city districts. Urban green and trees are effective mitigation tools for heat stress, which is observed in both measurements and model results, being most effective during the hottest hours of the day when they lower heat stress to less health‐impacting levels. Future simulations show a strong increase in the spatial extent and intensity of extreme temperatures within the city. This impacts city dwellers, which will consequently experience much more days with extreme heat stress levels towards the future, doubling or tripling depending on the climate scenario. Socio‐economic impacts for mid‐century are quantified, noting increases in heat‐related mortality of several percentages compared to present‐day values. Additionally, negative economic impacts of several percentages of the Gross Domestic Product are projected as heat stress will prohibit performing moderate or high‐intensity activities during the hottest hours of the day, even in the shade.

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Section: Methodsmentioning

confidence: 99%

High resolution heat stress over a Sahelian city: Present and future impact assessment and urban green effectiveness

Souverijns,

De Ridder,

Takacs

et al. 2023

Intl Journal of Climatology

Self Cite

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“…In the past ten years, the acceleration of urban development and the release of anthropogenic heat have led to an increasing urban heat island effect (Oke et al 2017), and this enhanced effect has become an urgent obstacle to sustainable development, affecting the morbidity and mortality caused by heat stress in the surrounding environment (Chapman et al 2017;Souverijns et al 2022), the cooling demand of indoor spaces (Santamouris 2020;Xu et al 2023b), as well as the degradation of air quality, deterioration of the water environment, and disturbance of biological habitats. Therefore, by means of forecasting, determining feasible measures in the urban environment to reduce the impact of the UHI can provide a scienti c reference for future sustainable urban development and planning.…”

Section: Introductionmentioning

confidence: 99%

The effect of green stormwater infrastructures in urban tier human thermal comfort—a case study in high-density urban blocks

Xu,

Hong,

et al. 2024

Preprint

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Using green stormwater infrastructure (GSI) is the main method of greening and cooling high-density blocks. Many studies have been conducted to evaluate the effect of a single GSI on thermal comfort on sunny days. However, GSI often occurs in combinations, and assessment of GSI cannot ignore the effect of rainwater on the thermal comfort improvement. Therefore, based on measured data of a real urban area of Nanjing, China, this study used 45 GSI single and combination simulation scenarios and three local climate zone (LCZ) baseline scenarios to compare and analyze three high-density blocks in the city. The physiological equivalent temperature (PET) was calculated using the ENVI-met specification to evaluate outdoor thermal comfort. The study produced the following results. (1) To improve outdoor thermal comfort, compact high-rise and mid-rise areas require more abundant GSI combinations, but only using a single GSI can have a good effect in compact low-rise area. (2) In extreme high-temperature weather, rainfall is a necessary condition for improvement of thermal comfort by GSI, and complex GSI can extend the thermal comfort improvement time following rainfall by more than 1 hour. (3) To improve the thermal comfort of a potential area of outdoor crowd activity to the greatest extent, shading and tree setting should be added based on the premise of increasing the combinations of GSI, and the efficiency of improvement can reach as high as 54.23 %. The results of the study indicated that future GSI construction in high-density blocks should focus on different combinations of GSI based on different LCZs. This conclusion provides a reference for other regions in Southeast Asia, where GSI construction systems should be studied and formulated in accordance with different LCZs.

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“…In the past ten years, the acceleration of urban development and the release of anthropogenic heat have led to an increasing urban heat island effect [1], and this enhanced effect has become an urgent obstacle to sustainable development, affecting the morbidity and mortality caused by heat stress in the surrounding environment [2,3] and the cooling demand of indoor spaces [4,5], as well as the degradation of air quality, deterioration of the water environment, and disturbance of biological habitats [6]. Therefore, by means of forecasting, determining feasible measures in the urban environment to reduce the impact of the UHI can provide a scientific reference for future sustainable urban development and planning.…”

Section: Introductionmentioning

confidence: 99%

“…The purposes of this study were to determine (1) the optimal combination of GSI for different local climate zones (LCZs) and their combined effects on pedestrian-level thermal comfort, (2) the degree of response of different GSI facilities to rainwater, and (3) the impact of GSI construction on major pedestrian recreation areas. To compare the efficiency of thermal comfort improvement, a new physiological equivalent temperature (PET)-derived index (%DPET) [40] was introduced.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Green Stormwater Infrastructures on Urban-Tier Human Thermal Comfort—A Case Study in High-Density Urban Blocks

Xu,

Liao,

Hong

2024

Forests

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Green stormwater infrastructure (GSI) is a key approach to greening and cooling high-density blocks. Previous studies have focused on the impact of a single GSI on thermal comfort on sunny days, ignoring rainwater’s role and GSI combinations. Therefore, based on measured data of a real urban area in Nanjing, China, this study utilized 45 single-GSI and combination simulation scenarios, as well as three local climate zone (LCZ) baseline scenarios to compare and analyze three high-density blocks within the city. Among the 32 simulations specifically conducted in LCZ1 and LCZ2, 2 of them were dedicated to baseline scenario simulations, whereas the remaining 30 simulations were evenly distributed across LCZ1 and LCZ2, with 15 simulations allocated to each zone. The physiological equivalent temperature (PET) was calculated using the ENVI-met specification to evaluate outdoor thermal comfort. The objective of this research was to determine the optimal GSI combinations for different LCZs, their impact on pedestrian thermal comfort, GSI response to rainwater, and the effect of GSI on pedestrian recreation areas. Results showed that GSI combinations are crucial for improving thermal comfort in compact high-rise and mid-rise areas, while a single GSI suffices in low-rise areas. In extreme heat, rainfall is vital for GSI’s effectiveness, and complex GSI can extend the thermal comfort improvement time following rainfall by more than 1 h. Adding shading and trees to GSI combinations maximizes thermal comfort in potential crowd activity areas, achieving up to 54.23% improvement. Future GSI construction in high-density blocks should focus on different combinations of GSI based on different LCZs, offering insights for GSI planning in Southeast Asia.

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Urban heat in Johannesburg and Ekurhuleni, South Africa: A meter-scale assessment and vulnerability analysis

Cited by 15 publications

References 71 publications

High resolution heat stress over a Sahelian city: Present and future impact assessment and urban green effectiveness

High resolution heat stress over a Sahelian city: Present and future impact assessment and urban green effectiveness

The effect of green stormwater infrastructures in urban tier human thermal comfort—a case study in high-density urban blocks

The Effect of Green Stormwater Infrastructures on Urban-Tier Human Thermal Comfort—A Case Study in High-Density Urban Blocks

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