Quantifying the Effects of Simulated Changes in Land Use/Cover on Flood Reduction: an Insight From Kigali

Abstract

In the recent decades, the rapid urbanization-induced land use/cover change has strongly altered patterns of surface runoff regimes in many cities in Sub-Saharan Africa's Countries. Yet, few studies have focused on the complexity of the anthropogenic stresses on surface runoff and flash flood in these growing cities. The present study assessed the effects of various land use/cover management scenarios with particular focus on decreasing of surface runoff and flooding in a highly urbanized watershed in Kigali, Rwanda. We used openLISEM hydrological model and the combination of remote sensing and fieldwork to quantify the impact of various land use/cover management scenarios on surface runoff and flash flood reduction. The model simulation results showed that the combined structural and ecosystem-based land use/cover management measures was the most effective technique for reducing surface runoff and flash flood in the study catchment. We observed an average reduction of 63%, 47% and 36% in surface runoff, flood volume and flooded areas, respectively. Furthermore, the implementation of land use/cover management measures would decrease the number of buildings affected by flash flood up to 35%. The results of land use/cover management scenarios could be useful for urban planners and policy makers for adopting suitable strategies to control flood related disaster in the fast-growing cities in Rwanda.