The Investigation of Trends and Wet and Dry Rainfall Cycles in North Africa (In Morocco, Algeria, and Tunisia) (1970–2023)

IPCC climate forecast models, applicable to the Maghreb countries (Morocco, Algeria, and Tunisia), predict a decrease in atmospheric precipitation, greater variability, and an increase in aridity. In recent years, the entire region has been experiencing unprecedented climate upheavals. Climatic droughts have become increasingly severe and recurrent (drastically reducing water stocks). We are also witnessing a remarkable increase in temperatures and a greater frequency of heat waves. Faced with these new provisions, this territory (long considered an area of water stress) is now subject to very strong tensions, which have led to a greater demand for water and a decrease in supply. To understand the intensity of this “climate–water” crisis, we propose an analysis of this priority issue based on the evolution of precipitation over more than half a century of records. To determine precipitation trends and define rainfall cycles in these three countries, the graphical chronological method of information processing (MGCTI) of the “BERTIN Matrix” type is used. Annual precipitation totals from 29 stations were used for the MGCTI (chronological graphic method of information processing) for the period 1970–2023. These data come from the national meteorological networks of the National Meteorological Office (ONM) for Algeria, National Institute of Meteorology (NIM) for Tunisia, and National Directorate of Meteorology (DMN) for Morocco, and the from the websites of the National Climatic Data Center (NCDC) and “TuTiempo Network”. Monthly pluviometric totals from three stations, Dar El Beida (Algeria), Casablanca (Morocco), and Tunis (Tunisia), as well as the monthly NAO (North Atlantic Oscillation) and MOI (Mediterranean Oscillation Index) were used for the wavelet coherence method for the period 1970–2022. Data analysis shows that the entire region is subject to four extreme precipitation cycles (dry and wet). The last dry period was remarkably intense and led to a sharp increase in water stress throughout the region. An analysis of monthly precipitation from three stations (Casablanca, Dar El Beida, and Tunis) using the wavelet coherence method also highlighted a close relationship with the “NAO” and “MOI” circulation.