Analysis of Historical Flood Frequencies and Magnitudes and Future Scenarios Forecasting in the Mono River Basin, West Africa

Global warming impacts are known as increasing in rainfall magnitude and frequency that lead to more intense and frequent river flooding. In recent years, there is an upward trend of floods in West African regions. As result, many countries like Togo and Benin have had catastrophic floods that affected thousands of people with loss of lives, damages, and properties. Mono catchment is indeed subject to flooding due to anthropogenic and natural climate changes impacts. This study aims to predict streamflow for the period between 1990 and 2020 using hydrological modeling at gauge stations; to analyze flood frequency and magnitudes over the Mono catchment for the historical period through an investigation of hydroclimate indices. Moreover, projected changes in floods hydroclimate indices in the catchment under representative concentration pathway (RCP) from a multi-model ensemble model are investigated. The results show that hydrological modeling reproduces seasonal streamflow with acceptable performance with Kling-Gupta Efficiency (KGE) and percent over calibration and validation periods. Finally, an upward flood frequency and magnitude are observed both for historical and future periods. The outcomes of this study suggest an urgent need to improve the functionality of early warning systems and increase societal resilience to warming climates over the catchment through sustainable policy strategies and governance measures.

Keywords: Flood Frequency and magnitude, Flood forecasting, Mono catchment, Togo-Benin