Impacts du changement climatique sur les régimes climatiques futurs en Afrique de l’Ouest : Cas du bassin versant du N’zi (Bandama, Côte d’Ivoire)

Abstract

The objective of this work is to analyze the impacts of climate change on future intra-annual weather patterns in the N’zi (Bandama) watershed, which straddles three main zones characteristic of the Ivorian climatic context. The study was based on a database of monthly rainfall and temperature data recorded in thirteen climate stations covering the reference period 1991-2020. Projected rainfall and temperature data from the Coordinated Regional Downscaling Experiment (CORDEX) climate model over the Africa zone (CORDEX Africa) with the RCP 8.5 scenario were also used. The methodology adopted is based on the application of climate indices at annual (De Martonne index, Moral index and UNEP index), seasonal (Péguy index and Angot index) and monthly (Gaussen index) scales for the present (1991-2020) and future (2050 and 2100) horizons. The results of the study showed that the climate of the N’zi (Bandama) watershed will change between the present (1991-2020) and future (2050 and 2100) periods. Indeed, the type of climate in the N’zi watershed will change from humid to semi-humid or even semi-arid, especially in the subtropical climate zone (Sudanese climate) in the north of the basin. The climatic regimes will maintain their modes, i.e. unimodal for the subtropical climate and bimodal for the tropical (central basin) and subequatorial (southern basin) climatic zones. However, major changes will be observed in the duration and seasonal periods. Indeed, a reduction in the duration of the rainy seasons in favor of the dry seasons and a dynamic of the different seasons in terms of beginning and end is noted, moving from the present (1991-2020) to the future (2050 and 2100). The rainfall totals show a differentiated seasonal evolution between the wet and dry semesters, with a general increase in precipitation during the hot periods in the future horizons.

Keywords

• Climate change
• N’zi Bandama
• Ivory Coast
• Climatic indices
• Climatic regimes