Study of the applicability of Sponge City concepts for flood mitigation based on LID (low impact development) measures: a case study in Conakry City, Republic of Guinea

Urban flooding is becoming a significant urban epidemic in many nations throughout the world as a result of land use and climate change, and regular heavy rains. In this study, we choose to investigate the viability of Sponge City concepts for flood mitigation based on low impact development (LID) strategies in a 26.66 km(2) area situated in Guinea's capital city of Conakry. The Storm Water Management Model (SWMM5) was used to simulate the impact of LID measures on the lowering of runoff peaks and node flooding. Simulation results before and after LID facilities are compared in order to understand how LID measures improve flood mitigation. The study showed that LID techniques effectively reduce runoff, which helps mitigate the effects of flooding. The study demonstrated that all LID, whether used singly or in combination, can lower runoff and flooding. However, when it comes to reducing runoff and flooding, LID-combinations perform better than individual LID implementations. For each of the five return periods, the LID-combination reduced runoff by 67.83, 65.02, 50.44, 40.18, and 35.88%, and reduced flooding by 85.32, 72.65, 54.05, 46.17, and 42.80%, respectively. Additionally, the reduction rate of overflow junctions is 100, 100, 80, 67, and 70%, respectively.