Variabilite Des Extremes Pluviometriques Sur Le Bassin Versant De La Riviere Bia (Sud-Est, Cote d’Ivoire)

Climate change is a reality which affects many climatic variables, including precipitation. The objective of this article is to study the extreme rain variability from a historical database (1941 - 2000). For this purpose, eleven (11) rainfall indices were calculated at the Adiaké, Bianouan, Ayamé, and Agnibilekro rainfall stations in Côte d'Ivoire. Due to lack of data on daily rainfall on the Ghanaian section of watershed, nine (9) monthly precipitations indices were estimated from monthly rainfall at the Enshi and Buakuc stations. The trend analysis of the precipitations indices show that a generalized downward was most significant in Adiaké compared to other stations. Furthermore, indices extreme thresholding (P99, P99p, P99,5 and P99,5p) have experienced a stable trend and a stationary evolution. All steps were detected in the non-stationary indices mostly observed after 1980 (late break) and before 1960 (precocious break)

Identifying drivers of streamflow extremes in West Africa to inform a nonstationary prediction model

West Africa exhibits decadal patterns in the behaviour of droughts and floods, creating challenges for effective water resources management. Proposed drivers of prolonged shifts in hydrological extremes include the impacts of land-cover change and climate variability in the region. However, while future land-degradation or land-use are highly unpredictable, recent studies suggest that prolonged periods of high-flows or increasing flood occurrences could be predicted by monitoring sea-surface temperature (SST) anomalies in the different ocean basins. In this study, we thus examine: i) what ocean basins would be the most suitable for future seamless flood-prediction systems; ii) how these ocean basins affect high-flow extremes (hereafter referred as extreme streamflow); and iii) how to integrate such nonstationary information in flood risk modelling. We first use relative importance analysis to identify the main SST drivers modulating hydrological conditions at both interannual and decadal timescales. At interannual timescales, Pacific Niño (ENSO), tropical Indian Ocean (TIO) and eastern Mediterranean (EMED) constitute the main climatic controls of extreme streamflow over West Africa, while the SST variability in the North and tropical Atlantic, as well as decadal variations of TIO and EMED are the main climatic controls at decadal timescales. Using regression analysis, we then suggest that these SST drivers impact hydrological extremes through shifts in the latitudinal location and the strength of the Intertropical Convergence Zone (ITCZ) and the Walker circulation, impacting the West African Monsoon, especially the zonal and meridional atmospheric water budget. Finally, a nonstationary extreme model, with climate information capturing regional circulation patterns, reveals that EMED SST is the best predictor for nonstationary streamflow extremes, particularly across the Sahel. Predictability skill is, however, much higher at the decadal timescale, and over the Senegal than the Niger catchment. This might be due to stronger impacts of land-use (-cover) and/or catchment properties (e.g. the Inner Delta) on the Niger River flow. Overall, a nonstationary framework for floods can also be applied to drought risk assessment, contributing to water regulation plans and hazard prevention, over West Africa and potentially other parts of the world

Principaux cours d'eau du bassin versant du fleuve Congo

This map shows the hydrometric stations located on the main rivers of the Congo River watershed in Africa.Cette carte présente les postes de mesures hydrométriques situés sur les principaux cours d'eau du bassin versant du fleuve Congo en Afrique

Principaux cours d'eau du Sud Cameroun, Afrique

This map shows the hydrometric stations located on the main rivers and watershed of South Cameroon, AfricaCette carte présente les postes de mesures hydrométriques du Sud Cameroun situés sur les principaux cours d'eau et bassins versants

Principaux cours d'eau de Côte d'Ivoire

This map shows the hydrometric stations located on the main rivers and watershed of the Ivory Coast in AfricaCette carte présente les postes de mesures hydrométriques de Côte d'Ivoire situés sur les principaux cours d'eau et bassins versant

Principaux cours d'eau du bassin versant du fleuve Volta, Afrique

This map shows the hydrometric stations located on the main rivers of the Volta watershed in Africa.Cette carte présente les postes de mesures hydrométriques situés sur les principaux cours d'eaudu bassin du fleuve Volta en Afrique

Les bases de données hydro-climatiques : Un outil pour étudier les changements environnementaux et leur impact sur la ressource en eau

Rouché Nathalie, Boyer Jean-François. Les bases de données hydro-climatiques : Un outil pour étudier les changements environnementaux et leur impact sur la ressource en eau. In: 35es journées de l’hydraulique de la Société Hydrotechnique de France. Hydrométrie 2013. Paris, 15-16 mai 2013. 2013