Hydrological variability of the Soummam watershed (Northeastern Algeria) and the possible links to climate fluctuations

• Published in: Arabian Journal of Geosciences
• Main Authors: Turki, Imen, Laignel, Benoît, Massei, Nicolas, Nouaceur, Zeneddine, Benhamiche, Nadir, Madani, Khodir
• Other Authors: Morphodynamique Continentale et Côtière (M2C), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Sciences Appliquées à L'Environnement (SCALE), Centre National de la Recherche Scientifique (CNRS)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Normandie Université (NU)-Université Le Havre Normandie (ULH), Normandie Université (NU), Université Abderrahmane Mira Béjaïa
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: NAO; Interannual frequency scales; SOI; Wavelet transform; Algerian rainfall fluctuations; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology; Soi; North Atlantic; North Atlantic oscillation
• Online Access: https://hal-normandie-univ.archives-ouvertes.fr/hal-02070418; https://doi.org/10.1007/s12517-016-2448-0

(IF 0.96; Q2) International audience The long-term variability of rainfall in the Soummam watershed (NE Algeria) has been analysed over the past 108 years using continuous wavelet method in order to identify the interannual modes controlling the rainfall variability. Statistical analyses of rainfall timeseries have shown its distribution following five periods of time, limited by a series of discontinuities around 1935, 1950, 1970 and 1990. The continuous wavelet transform have demonstrated different low frequency modes: 2–4, 4–8, 8–16 and 16–32 years.The annual band is expanded during the full study period with some pics around 1905, 1920–1935 and 1960; it shows a negative long-term trend, in particular since the period 1970–1990 when a major change has been identified. Then, the relationships between climate patterns of North Atlantic Oscillation (NAO) and Southern Oscillation Index (SOI) and the hydrological variability in the frequency domain have been investigated; they have shown a mean explained variance of 40 and 24 %, respectively. Such variances are less obvious for the annual mode and increase for the interannual frequencies. The coherence suffer from high perturbations since the period 1970–1990 when the NAO (SOI) shifts from negative (positive) phases to positive (negative) ones. Such anomalies are responsible for significant changes of rainfall variability, emphasising the global warming effects.