Twelfth International Conference on The Constructed Environment

Abstract

The objective of this work is to evaluate the impact of climate change on the runoff of the Chiffa River Basin by comparing two bias correction methods, “delta” and “quantile-quantile”. The results are provided by the GR2M conceptual rainfall-runoff model in the R environment, coupled with rainfall and temperature data outputs from two regional climate models CNRM and MPI of the Africa-Cordex programme and for two emission scenarios RCP4.5 and RCP8.5. The evaluation of the performance of the two models through bias estimation shows that the biases are very large and the simulated rainfall deviates greatly from the observed rainfall over the 1981-2005 control period, which is not the case for the temperatures, hence the need for bias correction. The GR2 hydrological model validated on the Chiffa Basin was used to simulate future flows over the period 2074-2099 by comparing simulations from uncorrected and quantile-quantile corrected input data. The results show that future flows simulated from raw data do not match the future evolution of precipitation and evapotranspiration, whereas flows from corrected data show better results, which highlights the importance of bias correction in hydrological impact studies. Finally, the CNRM and MPI climate models simulate a 5% reduction in annual runoff by the end of the 21st century according to RCP 4.5, while RCP 8.5 predicts a reduction of -10% which is more significant in winter and autumn.