Year: 2026
Type: article
Abstract: Rapid urbanisation in Kigali has intensified pressures on land, water resources and drainage infrastructure, replacing natural vegetation with impervious surfaces. The transformation has escalated the frequency of urban flooding, necessitating a spatial evaluation of the link between urban development and stormwater dynamics to prevent future hazards. This study examines the extent of urbanisation in Kigali and its influence on stormwater runoff. Specifically, the research aimed to map LULC changes between 2013 and 2023, estimate stormwater vulnerability using the SCS-CN method. The research applied a mixed-method approach by integrating GIS-based hydrological modelling (Rational Method and SCS-CN). Runoff volumes were estimated using both the Rational Method and the SCS-CN approach, integrating rainfall data, hydrological soil group classifications and LULC layers to quantify the impact of expanding impervious surfaces. Data from Meteo Rwanda, satellite images for LULC, Hydrological soil data and Kigali administrative shapefiles supported spatial analyses and vulnerability mapping. The result indicates a significant expansion in built-up areas from covering 25.3% of the city in 2013 to 32.6% in 2023, which directly correlates with an increase in surface runoff volumes. The hydrological analysis revealed that dense urban zones, situated on Hydrologic Soil Group D, show high Curve Numbers (CN 90–98), which indicate very low infiltration rates and severe flood vulnerability. It also revealed that runoff volume have increased due to the expansion of impervious surface. These findings demonstrate that continued urban expansion without adequate stormwater controls increases flood vulnerability across Kigali. Kigali City authorities should strongly enforce urban planning regulations that limit impervious surfaces in high-vulnerability zones and adopt nature-based and stormwater management techniques such as green infrastructure, permeable pavements and rainwater harvesting.
Institutions: University of Lay Adventists of Kigali, INES-Ruhengeri
Language: English
Subfield: Environmental Engineering
Field: Environmental Science
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7166304971