Characterization of the urban heat Island phenomenon in Niamey, Niger, in the context of climate change

In African cities, urban areas often experience a microclimate characterized by significantly higher temperatures than surrounding rural regions, a phenomenon known as the Urban Heat Island (UHI) effect. This effect is frequently attributed to poorly planned urban development and can have harmful health consequences due to increased thermal stress. This study evaluates the intensity of the UHI in Niamey based on urban morphological parameters, specifically building height and street width. Data were obtained from the National Geographic Institute of Niger (IGNN) and the National Directorate of Urban Planning of Niger (DNUN). Two main indicators were employed: the aspect ratio (AR) and a thermal index related to urbanization ), which reflects the potential amplification of heat perception in urban settings. The results reveal that UHI intensity decreases linearly with increasing building height when street width ranges from 10 m to 100 m. The recorded thermal amplitude varies between −5.74 °C and +3 °C. At the same height of building, UHI intensity also decreases as street width increases.