http://197.159.135.214/jspui/handle/123456789/971 2026-04-23T15:09:26Z 2026-04-23T15:09:26Z Gnigba, Issoufou Yangouliba http://197.159.135.214/jspui/handle/123456789/1073 2026-02-20T10:35:57Z 2023-07-28T00:00:00Z

Impacts of Climate, Land Use, and Water Management Changes on the Hydropower Potentials of the Bagre Dam, Burkina Faso Gnigba, Issoufou Yangouliba This study focused on the impacts of climate, land use, and water management changes on the hydropower potentials of the Bagré dam in Burkina Faso. The specific objectives are (i) the analysis of hydro-climatic variability and upstream reservoir management impact on the hydropower generation at the Bagré dam, (ii) the determination of the past and future land use/land cover (LULC) dynamics in the Nakambé River Basin (NRB), (iii) the assessment of climate and LULC changes impacts on the hydropower potentials at the Bagré dam, and (iv) the assessment of impacts of changed water management on the hydropower potentials at the Bagré dam. Datasets used were comprised of historically observed and reanalysis climate (W5E5), and hydrological time series for break years detection, trend analysis, and correlation investigation. In addition, Landsat images (1990, 2005, 2020) and ground truth data were used for LULC mapping and projection. Downscaled and Bias corrected data from the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP3b) Global Climate Models, water management, and reservoirs parameters data were integrated into the Soil and Water Integrated Management (SWIM) model to assess changes in hydropower generation for the mid (2035-2065) and far (2065-2095) future due to climate, land use, and water management changes. The results showed an annual positive trend in hydropower generation and inflow due to the construction of the Ziga dam in 2000 and its management change in 2005, respectively. In terms of LULC dynamics, from 1990 to 2020, woodland and shrubland decrease to the benefit of cropland, bare land/built-up, and water bodies. By 2050, woodland and shrubland may continue to decrease under the Business-as-usual (BAU) scenario. However, under an afforestation scenario, woodland and shrubland would slightly increase even though cropland will be the dominated land use of the basin. The results also showed that hydropower generation would increase in the mid (15-24%) and far (1.7-35%) future under climate change scenarios, relative to the baseline period (1984-2014). Furthermore, the future LULC change could increase the hydropower potential. Yet, the increment would be less under an afforestation scenario compared to a BAU LULC. For the hydropower generation change, climate change is responsible for 60-98% while LULC change is responsible for 2-40%. The future water allocation from Ziga reservoir would reduce the inflow by -2 m3/s in the future. This inflow decrease, in addition to the increasing water withdrawals for irrigation supply at the Bagré dam would cause a strong decrease in hydropower generation, which could be more pronounced under SSP126 and BAU LULC, compared to SSP370 and afforestation scenarios. This work pointed out the challenges for the Bagré dam operation to supply electricity in the future and can be used as a guideline for policy makers to address the future impacts of climate, land use, and water management changes on water resources in the NRB. A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use and the Universite Abomey Calavi, Cotonou, Benin, in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Climate Change and Water Resources

2023-07-28T00:00:00Z Fofana, Mohamed http://197.159.135.214/jspui/handle/123456789/1072 2026-02-20T10:28:49Z 2023-05-24T00:00:00Z

Flood Risk Reduction through the Assessment of Flood Forecasting System in the Upper Niger River Basin in Mali. Fofana, Mohamed This work was based on the issue of flood risk reduction through the assessment of a flood forecasting system. First of all, an overview of the flood forecasting system already implemented in Africa, especially in West Africa is carried out. Secondly, the trend analysis of flood events as well as their relationship with extreme rainfall is performed in Bamako. Thirdly, the hydrological models are calibrated and validated using the observed rainfall data. And lastly, the flood forecasting system is implemented in order to mitigate the coming floods in the study area. It allows the population to take necessary advances against floods, reducing considerably the flood impacts. HBV, HEC-HMS, SWAT, WRF-Hydro are the hydrological models the most used for the flood forecasting issues in Africa. From 1982 to 2019, the flood events historical trend in Bamako has increased as well as the flood victims. The extreme rainfall indices (RX1 day, RX5 day, R99P, PRCPTOT, CWD) show the same trend increasing during the same period 1982 to 2019. Therefore, a strong relationship between flood occurrences and extreme rainfall is identified. Most of the years where floods occurred in Bamako correspond to the years of high rainfall value, especially for the R99P. However, it has been observed that the rainfall responsible for flood in Bamako is approximatively 47mm, which is far from being exceptional. It is in the range of normal to severely abnormal classes; meaning that there are other causes that should be added to the extreme rainfall leading to flood events. Non-maintenance of channels, building houses on the way of the river-bed in addition to the soil destruction, could be considered as the major causes to be linked to the extreme rainfall. The flood forecasting system was explored in the study area through two hydrological models HBV and HEC-HMS. Both of the models are well calibrated and validated with satisfactory model efficiency values for the four days ahead NCEP rainfall data. Nash values are respectively 0.74, 0.76, 0.71, 0.62 for the 24h, 48h, 72h, and 96h ahead precipitation during the calibration and 0.82, 0.84, 0.77 and 0.76 during the validation for the HEC-HMS model respectively for the 24h, 48h, 72h and 96h ahead precipitation. For the HBV hydrological model, Nash values for the calibration are respectively 0.67, 0.86, 0.83, 0.80 for 24h, 48h, 72h and, 96h. During the validation, Nash values are 0.78, 0.78, 0.83, 0.80 for respectively 24h, 48h, 72h and 96h ahead precipitation. This interesting finding confirms the suitability of these models to be used for the flood forecasting system in the area. PoD and FAR indices calculated, gave satisfactory results of NCEP center data, and more success than false alarm rate was obtained. The knowledge of the forecasted rainfall can allow a better management of the Selingue dam, reducing floods impact and producing sufficient energy for the population. A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use and the Universite Abomey Calavi, Cotonou, Benin, in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Climate Change and Water Resources

2023-05-24T00:00:00Z Kwawuvi, Daniel http://197.159.135.214/jspui/handle/123456789/1071 2026-02-20T10:23:43Z 2023-04-24T00:00:00Z

Intra-Seasonal Rainfall Variability and its Implications on Streamflow in the Oti Basin, West Africa Kwawuvi, Daniel This study assessed the intraseasonal rainfall variability and its implications on streamflow in the Oti River Basin in West Africa. The specific objectives were to: (i) determine the intra-seasonal rainfall variability and trends for the historical period (1981-2010) and future period (2021-2050) in the Oti basin. (ii) determine the projected changes in intra-seasonal rainfall variability indicators in the Oti basin for the future period (2021-2050) and (iii) assess the impact of intra-seasonal rainfall variability on streamflow using the Hydrologiska Byråns Vattenbalansavdelning (HBV) model. The analysis was performed using high-resolution and quality-controlled climate data from the Ghana Meteorological Agency, National Meteorological Service of Togo, Meteorological Department of Benin, Climate Hazards Infrared and Precipitation Stations (CHIRPS), and NASA-POWER. The analysis for the future period was performed under RCP4.5 and RCP8.5 scenarios using a multi-model mean ensemble of eight bias-corrected regional climate models based on the quantile-quantile mapping method and from the Coordinated Regional Climate Downscaling Experiment (CORDEX-Africa). The study also used discharge data from the Water Resources Commission, Ghana, Water Resources Directorate (Togo), National Hydrological Service (DGIRH) of Burkina Faso and the Direction Generale de L’eau, Benin. The study revealed a likely decline in mean rainfall in the future by about 103.6 mm/yr (RCP4.5) and 45.9 mm/yr (RCP8.5). It also projected a decline in mean rainfall during the rainy season by about 90.8 mm/yr (RCP4.5) and 34.6 mm/yr (RCP8.5). The study further found a late onset of rains in the basin by about +16 days (RCP4.5) and +15 days (RCP8.5) which would possibly have a rippling effect on rainfall cessation in the basin causing it to occur earlier by a decrease of about 21 days under both RCP4.5 and RCP8.5 scenarios, with regards to the historical period. This subsequently resulted in shortening the length of rainy season by about 37 days (RCP4.5) and 36 days (RCP8.5). The number of wet and dry days are projected to increase and decrease respectively. Additionally, the streamflow of the basin was evaluated and projected for the future using the HBV hydrologic model. The mean multi-model ensemble predicted an increase in mean monthly streamflow at all sub-basins in the future (2021-2050) relative to the historical period (1981-2010) except Arly which is anticipated to have a decrease in its streamflow by about 2.79% (RCP4.5) while it will increase by about 31.17% (RCP8.5). The anticipated variations in the rainfall could affect the scheduling of agriculture, its sustainability and could place the basin a water-related stress. A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use and the Universite Abomey Calavi, Cotonou, Benin, in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Climate Change and Water Resources

2023-04-24T00:00:00Z Amichiatchi, N'da Jocelyne Maryse Christine http://197.159.135.214/jspui/handle/123456789/1070 2026-02-20T10:17:10Z 2024-05-22T00:00:00Z

Assessment of the Impact of Climate Change on Hydrological Extremes in Cote D’ivoire Amichiatchi, N'da Jocelyne Maryse Christine Les conditions hydrométéorologiques extrêmes, en particulier les inondations et les sécheresses, sont devenues des catastrophes naturelles annuelles en Côte d’Ivoire, causant des dommages matériels importants, des décès, et l’évacuation de la population, avec très souvent des difficultés pour l’approvisionnement en eau potable aux populations. Cette étude évalue l’impact du changement climatique sur les extrêmes hydrologiques (précipitations et débit) dans les différentes zones climatiques de la Côte d’Ivoire. Les objectifs de ce travail sont: (i) d’analyser les tendances hydro-climatiques historiques (précipitations et débits) de 1970 à 2017 et de connaitre l’effet de la variabilité des précipitations sur les débits d’étiage et de crue des bassins hydrographiques; (ii) d’étudier la performance des modèles hydrologiques GR4J, GR5J et HEC-HMS à simuler les débits d’étiage et de crue des bassins d'étude; (iii) d’examiner l’impact du changement climatique sur des phénomènes hydro-climatiques extrêmes selon les scénarios climatiques RCP4.5 et RCP8.5 pour la période de 2020 à 2050 avec les models climatiques suivants CM54,CNRM et MPI. Les données journalières de pluie, de débit, d’évapotranspiration (observées et futures) et les images satellitaires ont été les principales données de cette recherche. Ainsi, pour atteindre nos objectifs, plusieurs méthodes ont été utilisées. D’abord, l’extraction des différents indices des extrêmes hydro-climatiques, suivi de l’analyse de leurs fluctuations interannuelles par élimination des variations saisonnières à l’aide du filtre Hanning passe-bas d’ordre 2. Ensuite, l’analyse des tendances à l’aide du test Mann-Kendall modifié (MMK) et la détection d’homogénéité par le test d’homogénéité normale standard (SNHT) à un niveau de confiance de 0,05. Enfin, la simulation des extrêmes hydrologiques et l’étude des impacts du changement climatique futur par la modélisation hydrologique. Les résultats obtenus montrent que les indices d’extrêmes pluviométriques et les extrêmes hydrologiques de crue ont connu une tendance à la baisse, tandis que ceux des étiages, une tendance à la hausse. Les modèles hydrologiques, quant à eux, ont pu montrer une bonne performance à la calibration et à la validation avec des valeurs de Nash comprises entre 0.7 et 0.9. Le modèle GR5J, ayant montré la meilleure performance (valeurs de Nash comprises entre 0.7 et 0.9 en calage) sur tous les bassins d’études, a donc été utilisé dans la simulation des débits futurs sur ces différents bassins. Sous le scénario RCP 4.5 et selon les modèles climatiques CNRM, MPI, et ENSEMBLE, les indices pluviométriques pourraient connaître des tendances non-significatives à l’horizon 2020-2050. Sous le scénario RCP 8.5 et selon les modèles CM5Aet CNRM, les indices Pmaxan et Rx5days connaitront une tendance significative à la hausse. Une tendance non-significative a été observée dans les modèles MPI et ENSEMBLE. Les indices de débits extrêmes à l’horizon 2020-2050 pourraient connaître une tendance non-significative dans leur ensemble. Cependant, sous le scénario RCP4.5, l’indice de crue QMAXAN connaitra une hausse significative sur le bassin versant de la Bagoue, et sous le scénario RCP 8.5, les indices de crue QMAXAN, QX5days enregistreraient une baisse significative dans le nord du pays. Les indices d’étiage pris dans leur ensemble sous les scénarios RCP 4.5 et RCP 8.5 connaitront une baisse significative à l’horizon 2020-2050 sur les différents bassins d’étude. Aussi, l’évaluation de la dynamique de l’occupation du sol sur les extrêmes a été mise en évidence par plusieurs méthodes. Elle a relevé que du sud au nord et de l'ouest à l'est de la Côte d’Ivoire, on observe une bonne régression de la forêt ou de la savane, des ressources en eau, et une augmentation de l'habitat et des zones cultivées d'un endroit à l'autre. En outre, la relation entre l’évolution de l’indice de végétation (NDVI) et les indices extrêmes de pluie a montré une corrélation négative non-significative en général sur les bassins versants étudiés. De même, cette analyse a révélé une corrélation positive entre les indices de végétation (NDVI) et les indices extrêmes de débits dans son ensemble. De plus, l’impact du changement climatique affectera les paramètres avec une diminution dans les moyennes de pluies annuelles, les débits moyens, l'évapotranspiration, et une augmentation des températures. Ce travail a permis de comprendre le comportement hydrologique à travers l'étude et l'évaluation des performances de certains modèles hydrologiques par la simulation et l’évaluation de l’impact du changement climatique sur certains paramètres climatiques et des indices extrêmes hydro-climatiques. Ces connaissances seront utilisées pour planifier des politiques et des stratégies afin de se préparer aux défis potentiels qui résulteront des impacts du changement climatique dans les zones étudiées. A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use and the Universite Abomey Calavi, Cotonou, Benin, in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Climate Change and Water Resources

2024-05-22T00:00:00Z