**6. Conclusions**

Application of the standardized rainfall index (SPI) has made it possible to characterize drought situations in the Sassandra catchment area. During the 1971–2015 period, the driest sequences in terms of intensity (values between −1.53 and −3.06) and duration occurred. These dry events reached their peak in 1974, 1983, 1987, 1987, 2002 and 2003, with extremely severe droughts. Among the 10 stations that have been studied, those of Man, Guiglo, Touba, Odienné, Soubré, Seguéla and Vavoua seem to be the most affected by droughts. As for the Sassandra station, it seems to be more affected by a long dry period. As for the study of drought persistence using Markov chains 1 and 2, it made possible to determine the probability occurrence of droughts as well as to analyze their behavior in the basin. The results indicated that the succession of dry conditions increased during 1971–2015. The greatest probabilities for obtaining a doublet of successive dry years (D-D) and three consecutive dry years (D-D-D) were recorded in the southern and northern regions of the watershed. Markov chains 1 and 2 applied to a representative sample of 10 stations are found to provide a good regional drought indicator. Thus, the probability of a dry year in this basin will depend on the previous year's situation and even more on the condition of the year before. This study will enable populations, decision-makers, etc., to develop new water resource management strategies for the proper functioning of existing socio-economic infrastructures (hydroelectric and agricultural dams, etc.), water projects and the development of new farming systems to cope with the effects of climate change.

**Author Contributions:** N.S. and Y.A.N.G. developed the ideas; G.E.S. and N.D.H.M. contributed to the data processing. N.D.H.M. contributed to creation of the maps. N.S. analyzed the data and wrote the article with contributions from Y.A.N.G., N.E.S., N.D.H.M., and B.T.A.G.. Supervision and validation were provided by Y.A.N.G. and B.T.A.G.

**Funding:** This research received no external fundi.

**Acknowledgments:** The authors thank the National Meteorology Directorate (DMN) of SODEXAM (Company operating and Developing airports, Aeronautics and Meteorological) of Côte d'Ivoire, for data acquisition.

**Conflicts of Interest:** The authors declare no conflict of interest.
