Impacts of Climate, Land Use, and Water Management Changes on the Hydropower Potentials of the Bagre Dam, Burkina Faso

Abstract

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.