Sawadogo Zounabo Epouse Kouyate^1,, Soro Gneneyougo Emile², Kouakou Koffi Abdelaziz³, Goula Bi Tié Albert², Brou Yao Casimir⁴

Rainfall decline trend observed since 1970s in Côte d’Ivoire is still putting a strain on the annual recharge of dams and the satisfaction of crop irrigation water requirements. The aim of this study is to analyze the hydrological functioning of the Nanan agricultural dam in a context of climate variability. Several approaches were used to collect the data, including direct measurements, visual observation, surveys, interviews, and documentary research. The method used for the water balance was the principle of volume conservation (continuity equation), applied over two years (2016, 2017). This analysis shows that runoff accounts for 92% of the annual recharge of the Nanan dam. Of the water mobilized, 63% was used for irrigation, and uncontrollable losses amounted to 38%, of which 25% by infiltration and 12% by evaporation. The variation in annual stock was different from one year to the next, with a variation of -104,000 m³ in 2016 and +165,000 m³ in 2017. In short, the hydrological regime of the dam is closely linked to the rainfall regime. This characterisation could be used in a future climate projection simulation to analyze the impact of climate change on the dam's capacity to meet crop water requirements.

climate change, hydrological regime, water balance, irrigation, Yamoussoukro