Trends and variability in extreme precipitation indices over Maghreb countries

• Published in: Natural Hazards and Earth System Sciences
• Main Authors: Tramblay, Yves, El Adlouni, S., Servat, Éric
• Other Authors: Hydrosciences Montpellier (HSM), Institut de Recherche pour le Développement (IRD)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), The publication of this article is financed by CNRS-INSU.
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: MAGHREB; [SPI.GCIV.RISQ]Engineering Sciences [physics]/Civil Engineering/Risques; [SDE]Environmental Sciences; [SDE.MCG]Environmental Sciences/Global Changes; North Atlantic; North Atlantic oscillation
• Online Access: https://hal.science/hal-02414975; https://hal.science/hal-02414975/document; https://hal.science/hal-02414975/file/nhess-13-3235-2013.pdf; https://doi.org/10.5194/nhess-13-3235-2013

International audience Maghreb countries are highly vulnerable to extreme hydrological events, such as floods and droughts, driven by the strong variability of precipitation. While several studies have analyzed the presence of trends in precipitation records for the Euro-Mediterranean basin, this study provides a regional assessment of trends on its southernmost shores. A database of 22 stations located in Algeria, Morocco and Tunisia with between 33 and 59 yr of daily precipitation records is considered. The change points and trends are analyzed for eleven climate indices, describing several features of the precipitation regime. The issue of conducting multiple hypothesis tests is addressed through the implementation of a false discovery rate procedure. The spatial and interannual variability of the precipitation indices at the different stations are analyzed and compared with large-scale atmospheric circulation patterns, including the North Atlantic Oscillation (NAO), western Mediterranean Oscillation (WEMO), Mediterranean Oscillation (MO) and El Nino-Southern Oscillation (ENSO). Results show a strong tendency towards a decrease of precipitation totals and wet days together with an increase in the duration of dry periods, mainly for Morocco and western Algeria. On the other hand, only a few significant trends are detected for heavy precipitation indices. The NAO and MO patterns are well correlated with precipitation indices describing precipitation amounts, the number of dry days and the length of wet and dry periods, whereas heavy precipitation indices exhibit a strong spatial variability and are only moderately correlated with large-scale atmospheric circulation patterns.