Evaluating Hydrological Responses of Gidabo River Catchment to Climate Change: Rift Valley Basin, Ethiopia

Abstract

Water resources are stressed due to population increase and urbanization. Moreover, the climate change is further affecting the hydrological cycle. Hence, understanding the effect of climate change on various components of the hydrological cycle and water resources is crucial for the management of this essential resource. In this study, we used a hydrologic model to study the impact of future climate on the Gidabo River Catchment. The hydrologic model was created using the Soil and Water Assessment Tool (SWAT) model and the SWAT-CUP for the sensitivity analysis, calibration and validations of model parameters using monthly river discharges at three subbasin level. Future climate scenarios for periods 2020’s and 2050’s were applied using the Bias corrected precipitation, maximum and minimum temperature data from the four regional climate models CCLM4, RCA4, RACMO22T, and REMO2009 under RCP 4.5 and RCP 8.5 as input for the hydrologic model. Correlations between streamflow and meteorological variables were investigated, while nonparametric tests were applied to determine the trends and correlations. For future scenarios a significant increasing trends of annual and monthly mean temperature is found about 0.76 °C for RCP4.5 and 0.85 °C for RCP8.5 in the 2020s, and by 1.78 °C for RCP4.5 and 2.3 °C for RCP8.5 in the 2050s for the mid-term period, whereas during the whole period the annual and monthly precipitation in the basin did not exhibit similar trends although temporal and spatial variations were detected. The result of this study will provide crucial information to water resource managers for decision makings that address the consequences of climate change.