Abstract:
Heat-related problems have become a global issue resulted from climate change. Prolonged exposure
to extreme high temperatures increased the percentage of mortality and morbidity in cities worldwide.
Urbanization and population contribute to urban heat islands effect (UHIE). The purpose of this paper is to
prioritize urban areas at high risk for heat related incidents in mega cities and to propose the implementation of
urban green coverage (UGC) strategies which contribute to mitigating UHIE. The methodology includes a
review on the UHI problems, along with the cooling benefits the UGC can produce. Then, the study’s application
is mainly focused on Cairo Governorate, Egypt as an example of a developing country. Cairo Governorate, Egypt
lacks well maintained vegetation in almost all districts as results indicated that it has a mean normalized
difference vegetation index (NDVI) ranging from 0.08 to 0.25. The study adopts the Australian model developed
by Norton et al. [Landsc. Urban Plan. 134, 127 (2015)], which includes the intersection of three factors (heat
exposure, vulnerability, and behavioural exposure) to identify a high priority area. It was difficult to assess the
behaviour of population in outdoor public spaces in a city like Cairo; hence, the study follows “Crichton’s Risk
Triangle” conducted by Morabito et al. [PLoS One 10, e0127277 (2015)], to identify high risk areas based on the
intersection of three layers: (a) high day-time/night-time surface temperatures hazard; (b) total exposed
population in a city exposure; and (c) sub-populations at risk of being harmed during extreme heat
vulnerability. In the simulation, the risk assessment method simplifies the process of constructing the GIS
database as it is composed of layering system. The development of a Heat-related Vulnerability Index (HVI)
map for Cairo districts was conducted by over layering the natural hazard layer (land surface temperature) with
spatial demographic data using GIS Software. Results of risk maps of Cairo were presented and showed
normalized HVI values ranging between 0.0 and 1.0, which can be categorized into five risk levels (very low to
very high). Results also indicated that 13 out of the 46 districts in Cairo are at very high/high risk, while only 5
districts have a very low risk. Finally, a tool was established to map the population vulnerability to extreme heat
events by identifying high priority risk areas that requires urgent intervention by applying more UGC to
mitigate UHIE and climate action and adaptation.
