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Book chapter2022Peer reviewed

Hydrological Impacts of Projected Climate Change on Northern Tunisian Headwater Catchments—An Ensemble Approach Addressing Uncertainties

Dakhlaoui, Hamouda; Hakala, Kirsti; Seibert, Jan


The present study addresses the hydrological impact of climate change, and associated uncertainties, on Northern Tunisian headwater catchments, which serve as the main source of surface water for Tunisia. This study is based on a wide range of hydrological projections resulting from the factorial combination of modelling chain components comprising: eleven high-resolution EURO-CORDEX regional climate models (forced by general circulation models; GCM-RCMs), three rainfall-runoff models (RRM) (GR4J, HBV and IHACRES), two time periods (mid-term: 2040‒2070 and long-term: 2070‒2100) and two climate scenarios (RCP 4.5 and RCP 8.5). A quantile mapping bias correction method was applied to correct the climate simulations. Projections of discharge were analysed according to several metrics commonly used by water managers. We applied the analysis of variance (ANOVA) technique to quantify the contribution of the uncertainties related to different components in the modelling chain to the overall uncertainty. The results show a marked decrease of precipitation and an increase of temperature especially for the most pessimistic climate scenario (RCP 8.5) towards the end of the twenty-first century, reaching −26% and + 4 °C, respectively. The modelling results showed that the local hydrology of the study catchments will be substantially influenced by climate change. Overall, by the end of the century, discharge and soil moisture are expected to decrease by up to 58 and 30%, respectively. We find a significant similarity between the different RRMs in terms of hydrological projections despite their different structures. ANOVA partitioning among the sources of uncertainty shows that the uncertainty induced by the GCM-RCMs is the dominant source of uncertainty and is anticorrelated with the area of the catchment. This demonstrates the challenge of applying GCM-RCM output at fine spatial scales, especially for catchments smaller than their grid. In addition, uncertainty stemming from hydrological models was found to be greater during the dry season.

Published in

Title: Climate Change in the Mediterranean and Middle Eastern Region
ISBN: 978-3-030-78566-6Publisher: Springer

    Sustainable Development Goals

    SDG6 Clean water and sanitation
    SDG13 Climate action

    UKÄ Subject classification

    Oceanography, Hydrology, Water Resources
    Climate Research

    Publication identifier


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