Nguimalet C.R auteur aut IRD Orange Didier auteur aut IRD Waterendji J.P. auteur aut IRD Yambele A. auteur aut IRD text bookSection eng text/pdf born digital access The rainfall reduction in the 1970s, less marked in Central Africa than in West Africa, still had a major impact on the hydrological regimes of the region's large rivers. The study of the hydropluviometric behavior of the Ubangi River at Mobaye has the advantage of being a study of a basin excluding anthropogenic impact. Forest cover and population density have not changed since at least 1970. Statistical analysis of the breaks in the long rainfall time series to Mobaye (1938-2015) confirms a long period of drought from 1969 to 2006, corresponding to a reduction of 8% in rainfall. Also, the study of the corresponding hydrological series indicates a second downward break in 1981, marking an exceptional hydrological drought. Flows increased in 2013, a few years after the rainfall increase. The statistical study of the annual rainfall/flow series of the upstream basins over the period 1951-1995 (the Kotto River in Kembe and Bria, the Mbomu River in Bangassou and Zemio, and the Uele River + Bili hydrographic system) highlights different hydrological behaviors related to the vegetation cover. On the one hand, the savannah basins show a continuous hydrological deficit marked by a runoff coefficient (CE) that fell to only 5% from the 1990s. On the other hand, the basins under forest show a runoff increase since 1990, marked by a CE above 10%. Under savannah, the part of the flow infiltrating to recharge the aquifer would have decreased faster than under forest, which results in a runoff CE very significantly negatively correlated with the savannah area present in the studied watershed. specialized PRECIPITATION REGIME HYDROLOGIQUE PLUVIOMETRIE DEBIT VARIATION ANNUELLE SECHERESSE RUISSELLEMENT AQUIFERE ETUDE COMPARATIVE COUVERT VEGETAL SAVANE FORET DENSE COURS D'EAU BASSIN VERSANT SERIE CHRONOLOGIQUE CHANGEMENT CLIMATIQUE 1938 2015 CENTRAFRIQUE 062MECEAU Tshimanga R.M. ed. edt IRD Moukandi N'kaya G.D. ed. edt IRD Alsdorf D. ed. edt IRD 269 83-96 Washington (USA) AGU Hoboken Wiley 2022 269 https://www.documentation.ird.fr/hor/fdi:010087867 10.1002/9781119657002.ch6 9781119656975 [F B010087867] https://www.documentation.ird.fr/hor/fdi:010087867 https://www.documentation.ird.fr/intranet/publi/2023-10/010087867.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2023-05-09 2025-02-24 fdi:010087867 fre