The management water resource in our States is harder and harder lately because of the frequency and of the intensity of droughts. Senegal, as most tropical States, knew an alternation of wet and dry periods. In this climatic context more and more disrupted by the anthropological activities, it is essential to analyze the dry episodes on various climatic domains, in diverse temporal scales and by diverse indications to propose to the populations of the measures of mitigation or adaptation regarding management of water. In this article, pluviometric data of six stations located in three climatic domains were analyzed. The analysis used and compared the values of the rainfall deviations decimal logarithm index (RDI), the rainfall anomalies index (RAI) and the standardized precipitation index (SPI) calculated for timescales of 5 years, of 25 years and of 50 years. The results indicate that the most remarkable droughts due to their intensity, their duration and their frequency occurred during decades 1970 and 1980 whatever the index, the timescale and the used climatic domain. These dry episodes reached their paroxysm in 1972 and 1983 with droughts of an extreme severity. The climatic domains are affected well by drought, but to varying degrees. Besides, it appears that the ISP index and the long-term timescale seems the best suited to describe with more precision the dry episodes in Senegal, and most affected continental Sahelian domain.