Quantifying uncertainties of climate change impacts on hydropower potential under 1.50C and 2.00C GWLs in the Lagdo dam, Cameroon

This study evaluates the climate change impacts on hydrological components and hydropower potential in the Lagdo dam, headwaters of the Benue River Basin (HBRB) under 1.5o and 2.0oC global warming levels (GWLs) and quantifies the main sources of uncertainty in the modeling chain. Precipitation and temperature from 17 CORDEX-Africa members combined 09 general circulation models (GCMs) and five high-resolution (0.44o) regional climate models (RCMs) under two representative concentration pathways (RCPs) 4.5 and 8.5 were used to run two calibrated Lumped-conceptual hydrological models (HMs) (HBV-Light and HYMOD). An analysis of variance (ANOVA) decomposition was used to quantify the uncertainties related to each impact modeling chain step for hydrological projections and hydropower potential calculation process, namely RCP scenarios, GCMs, RCMs and HMs. Results reveal a high uncertainty in both climatic and hydrologic parameters. Under RCP4.5 (RCP8.5) and relative to the baseline period (1971-2000), values varied from -6.03(-5.63) to +8.33(+8.31) (-4.45(-4.62) to +6.75(+11.19))% for annual precipitation, 0.73(1.17) to 2.11(2.74) (0.54 to 2.14(2.70))oC for average temperature, and from 3.75 to 12.30 (2.65 to 12.22)% for annual potential evapotranspiration (PET) under both 1.5(2.0)oC GWLs. The combination of change in  precipitation and increase of PET results in a significant decrease in hydropower generation in the HBRB associated with the large band of uncertainties. Results of the ANOVA sensitivity test also reveal that for the four main sources of uncertainty, two of them (GCMs and RCMs) significantly contribute to the uncertainty to the impact modeling chain.

The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)