Impacts of Climate Change on Agroclimatic Indicators in West Africa: Case Study of the N’zi (Bandama) Watershed in Côte d'Ivoire

In a context of climate change observed in West Africa for several decades, knowledge of agroclimatic indices is essential in order to analyze and predict the potential impacts of climate change on agriculture with a view to adaptation. This study aims to analyze the impacts of climate change on agroclimatic indicators such as agricultural humidity index, agricultural water stress index and agricultural water need satisfaction index within the main Ivorian climatic regimes across the N'zi (Bandama) watershed. The study was based on an interannual analysis of the agroclimatic indicators selected for the vegetative period in general and the spring and summer periods in particular, during the current normal reference period (1991-2020). The interannual analysis showed that the potential evapotranspiration (PET) observed over the whole of the current normal reference period 1991-2020 during the vegetative period as well as during the spring and summer periods, experienced an increase over all the climatic zones with the pre-eminence of the spring period over the summer period. However, the actual evapotranspiration (AET), although characterized by a general upward trend regardless of the climatic zone, sometimes experiences divergent trends in the PET. The interannual evolution of the water balance expressed by the water humidity index during the different cropping periods highlights a predominance of deficit years. The N'zi watershed was marked by water stress varying between the low level and the high level during the period 1991-2020. A deterioration in the rate of satisfaction of agricultural water needs was also highlighted, going from a very satisfactory level to a weakly satisfactory level. However, the evolution of agroclimatic indicators differs according to climatic zones and cropping seasons (crop season, spring and summer). The results obtained constitute a series of important indicators for the economic development of a country with an agricultural vocation such as Côte d'Ivoire. The study of the evolution of these indicators on a seasonal scale would constitute a metric for an analysis in the short (horizon 2030), medium (horizon 2050) and long term (horizon 2100) and will provide information on risks and/or opportunities for the development of certain crops (cereals, etc.).