SUMMARY
The Bia basin covers an area of 9650 km2 and extends between Côte d'Ivoire and Ghana. The chronic flows at the outlet of this basin contain gaps that can extend over months while their continuity must be ensured for a good control of the contributions to the lakes of Ayamé 1 and 2. The objective of this work is to help improve our ability to simulate runoff in the Bia watershed. To do this, the stationary periods were determined in the evolution of the annual rainfall and discharge of the watershed with Hubert's stationarity test before calibrating and validating the model using the differential split-sample test methods and cross simulation. Nash values of up to 80% show that this model can simulate flows over the Bia watershed.