Drivers of Streamflow Variability in West and Central Africa

Abstract : The unprecedented droughts episodes that struck West Africa during 1970s and 1980s, have triggered a plethora of studies investigating rainfall variability and its impacts on food production systems. In general, studies exploring impacts of rainfall variability on streamflow were restrained to basin scale with few of them investigating impacts at the regional scale. This study aims at bridging the gap through an estimation of streamflow variability over West and Central Africa. First, streamflow time series retrieved from the HSM-SIEREM database are completed based on correlations between gauging stations. This is an important outcome of this study, which proposes to create a homogeneous streamflow database, for the first time, over this region. Runoff variability and trends in the region over the past decades are assessed using multi-temporal trend analysis on the filled time series between 1950 and 2010. Second, a wavelet-based approach is used to detect the dominant timescales of streamflow variability. The challenge is to separate human (e.g. land use) induced and climate induced variability in the changes of hydrological regimes. The detected trends are significant for most of the stations and highlight the fluctuations of rainfall during the past decades. The findings emphasize interannual to decadal variability and significant correlations between rainfall and streamflow for some of the regions implying the importance of climate variability on hydrological regimes. Regions where no significant correlations with climatic variables are found underline the impacts of anthropogenic activity mainly land use and water management practices on streamflow variability. Even though, relationships between rainfall and streamflow are very complex and difficult to capture, defining the issue on a regional scale provides hints to improve hydrological modelling practices.
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https://hal.umontpellier.fr/hal-02127076
Contributeur : Pascale Roussel <>
Soumis le : lundi 13 mai 2019 - 11:04:22
Dernière modification le : mardi 28 mai 2019 - 13:48:10

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  • HAL Id : hal-02127076, version 1

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Moussa Sidibe, Bastien Dieppois, Mahé Gil, Jean-Emmanuel Paturel, Nathalie Rouché, et al.. Drivers of Streamflow Variability in West and Central Africa. AGU Fall Meeting 2016, Dec 2016, San Francisco, United States. ⟨hal-02127076⟩

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