Hydrodynamic simulation of rainfall-induced flooding in cities of low- and middle-income countries: A case study of Harare

Urban areas in Low- and Middle-Income Countries (LMICs) are experiencing increased flooding due to rapid urbanisation and a rise in the incidence and intensity of severe rainfall. This study develops an approach to model flooding in cities of LMICs using a high-performance hydrodynamic computational model, largely driven by open data. The strategy is substantiated by simulating the 09-21 January 2021 high rainfall event in the 2,245km2 Chivero Catchment, which impounds Harare City. Coarse-resolution Shuttle Radar Topography Mission (SRTM) topographical data was corrected to improve modelling accuracy. Simulations driven by the corrected SRTM data demonstrate the model’s ability to simulate the floodwater levels and to approximately predict the spatial extent of flooding. Simulations driven by the original SRTM data generally underestimated flood depths. The generated simulation results are used to inform the design and testing of green infrastructure (GI), which led to a 25% decrease in the spatial extent of flooding. Appendix 1 has been removed and is available on request.