Quantifying climatic heavy-precipitation-induced floods in West Africa using multiple precipitation indices

Abstract

Extreme precipitation events, especially climatic heavy precipitation-induced (CHP-induced) floods, pose substantial negative impacts on a myriad of socio-economic drivers. Incidents related to extreme precipitation events result in revenue loss, thereby negatively affecting national economies, and there is a growing need to advance studies that promote early warning and rapid resilience building across West Africa. Despite the region’s vulnerability to climate change, studies on flood events have barely compared multiple indices in order to provide a true representation of meteorological floods in the region Using multiple precipitation indices (Standardized Rainfall Anomaly, Standardized Precipitation Index and Rainfall Anomaly Index), CHP-induced flood events were assessed both historically and into the far-future. The projections were estimated under three Shared Socioeconomic Pathways (SSPs; SSP1-2.6, SSP3-7.0 and SSP5-8.5) and over three demarcated zones of West Africa (Guinea Coast [GC], Savanna [SAV] and Sahel [SAH]). The findings from the study indicate an expected intensification in future flood potential, particularly in the Savanna and Sahel. Contrastingly, flood potential in the Guinea Coast is projected to remain nearly similar to the historical records. On the impacts of emissions scenarios on projected CHP-induced floods, an increase in the mean flood count and maximum flood could potentially result from rising emission concentrations. The findings of the study are useful for advancing current understanding of CHP-induced floods over West Africa, and planning effective mitigation and adaptation strategies to build resilience in the face of current to future episodes.

Keywords

• CHP-induced floods
• SPI
• Rainfall anomaly
• SSPs
• West Africa
• CMIP6