Characterization of Drought Events in South Oran and South Algiers Steppes in Algeria

Over the past three decades, Algeria has experienced a significant precipitation deficit that is characterized by recurring droughts. The present article aims at studying and describing the main characteristics of drought episodes in the steppes of South Oran and South Algiers, over the period extending from 1978 to 2013. To do this, the characteristic parameters of the dry periods, i.e. their duration, intensity and frequency, were analyzed using three methods. The first one consists of calculating the Standardized Precipitation Index (SPI) using three time scales, i.e. 3, 6 and 12 months. The second one is the quintile method and the third one is the Chronological Graphical Method of Information Processing (MGCTI). The results obtained showed a great variability in the SPI values at the time scale of 3 months whereas at the time scales of 6 and 12 months, these values were stationary and revealed less frequent but more severe and longer dry sequences. The findings obtained when using both the quintile and MGCTI methods also revealed the severe and recurrent character of drought observed during the period from 1992 to 2002. The most significant drought events, in terms of intensity, duration and geographical extension, occurred during the years 1983/1984/1985 and then from 1999 to 2002 This phenomenon manifested itself in a similar way over the entire region under study.