Abstract

Understanding changes in precipitation intensity and frequency indices plays an important role in flood risk mitigation and water resource management. The objective of this paper is to assess future changes in extreme precipitation indices in the Oueme River basin at Bétérou compared to the reference period. To achieve this, the paper uses the ISIMIP approach to improve the usability of regional climate model projections for climate change impact studies. This impact study evaluates changes in some of the extreme climate indices recommended by the Expert Team Monitoring on Climate Change Detection and Indices. The bias correction approach helps to reduce differences between observed rainfall and the precipitation data from regional climate models (HIRHAM5, REMO, and RCA4). For future projections, the results indicate a mix of increases and decreases in precipitation intensity indices (simple daily intensity index and Max 5-day precipitation amount), ranging between -40 and 40% with HIRHAM5 and RCA4, while with REMO, only increases ranging between 2 and 80% are simulated under both RCP4.5 and RCP8.5 scenarios across the three time horizons: 2020s (2011–2040), 2050s (2041–2070), and 2080s (2071–2100), representing the near, mid, and far future. Regarding precipitation frequency indices (number of heavy precipitation events, number of very heavy precipitation events, consecutive dry days, and consecutive wet days), the results also show a mix of increases and decreases, ranging between -40 and 80%, over the three time horizons under both RCP4.5 and RCP8.5 scenarios using HIRHAM5, REMO, and RCA4 precipitation data.

Key words: Extremes precipitations indices, future projection, regional climate models, ISIMIP method, Ouémé River.