A new look at hydrology of the Congo Basin from the study of multi-decadal time-series of discharges

Abstract : First in Africa and second in the world in discharge and surface, the Congo Basin located in the heart of the African continent is crossed by the equator line. It plays a major role in energy balances, moisture flows, atmospheric circulation and exchanges between the two hemispheres, as well as in its contributions to the Atlantic Ocean. However, it remains poorly known and quite forgotten by the international scientific community. Nevertheless, thanks to a synthesis of previous and recent studies, and to the use of several statistical tests for the detection of ruptures in time-series, applied to the few long multi-decadal chronicles of available discharges recent updating on its main fluvial axes (Ubangui, Sangha, Kasaï, Lualaba, etc.), it was possible to highlight changes and trends in the hydrological functioning of the Congo River basin. Among the main results, it can be noted (i) that between several discontinuities in its flows, the 1970 hydro-pluviometric rupture is common to most of the tributaries of the Congo Basin, followed by significant reductions in flows depending on various factors (geographical situation, vegetation cover, surface conditions and land use, etc.), (ii) that peripheral rivers such as the Ubangui in the North continue to be subject to discharges deficits, with an increase of the duration and intensity of the falling stages, which is problematic for the reduction of the navigation period. Whereas (iii) from 1990 onward, discharges of Congo river at it main station seem returned to interannual average, with however an increase of the seasonal variability and the decrease of the Spring flood discharges, also remarked for tributaries with bimodal regime. This work explains (iv) some hydrological paradoxes specific to this basin which illustrate the complexity of its hydrological functioning, and finally shows (v) that the period of excess flow in the 1960s is the major anomaly of the Congo River on a continuous chronicle of discharges during 120 years. For the whole basin (vi) hydrological variations are mitigated compared to rainfall variations.
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https://hal.umontpellier.fr/hal-02149332
Contributeur : Sandrine Beraud <>
Soumis le : jeudi 6 juin 2019 - 12:05:46
Dernière modification le : vendredi 7 juin 2019 - 01:27:09

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  • HAL Id : hal-02149332, version 1

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Alain Laraque, Guy Moukandi N'Kaya, Jean-Emmanuel Paturel, Stéphane Delichere, Georges Gulemvuga, et al.. A new look at hydrology of the Congo Basin from the study of multi-decadal time-series of discharges. Chapman Conference on Hydrologic Research in the Congo Basin, Sep 2018, Washington, United States. ⟨hal-02149332⟩

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