The impacts of climate change on hydrological processes of Gilgel Gibe catchment, southwest Ethiopia

This demonstrates that changes in precipitation is not the only factor affecting surface water. This result was in line with previous studies on the Nile River. In the upper Nile, [65] found that hot, dry years are occurring more frequently due to rising regional temperatures. The spatial distribution of the hydrological process under the projected climate change for RCP4.5 and RCP8.5 is presented in the Figures. The catchment’s surface runoff, groundwater, and water yield were all reported to have decreased due to climate change, but the yields in each sub-basin varied. While temperature changes are projected to have indirect effects, spa- tiotemporal patterns and magnitudes of precipitation are predicted to directly disrupt the hydrological process. In both scenarios throughout the study projections taken into consider- ation, the upstream of the catchment is often anticipated to have the greatest decline in surface runoff, groundwater, and water yield. Under the RCP4.5 and RCP8.5 scenarios, the projection for the decline in surface runoff and water yield is greater in the intermediate than in the far future. In both scenarios, the southwest is where surface runoff is expected to decline at the slowest rate over the intermediate term and the far future, followed by the northeast. The southwest corner has a higher rate of groundwater and water yield decline. The highest rise in PET is shown by RCP8.5 around the outlet of the catchment in the mid future projection. In both scenarios, it was observed that the catchment’s surface runoff had decreased as a

result of climate change. The upstream of the catchment is frequently expected to have the Table 6. Changes of water balance components under a climate change. RCM RCP Time Period Surface Runoff (%) Groundwater flow (%) Water Yield (%) PET (%) CCLM4-8 RCP4.5 2041–2070 -7.61 -9.34 -8.92 16.01 CCLM4-8 RCP4.5 2071–2099 -14.96 -13.83 -14.01 19.02 CCLM4-8 RCP8.5 2041–2070 -12.65 -9.89 -10.58 16.69 CCLM4-8 RCP8.5 2071–2099 -9.57 -16.08 -13.76 22.67 HIRHAM5 RCP4.5 2041–2070 -7.79 -9.32 -8.78 16.15 HIRHAM5 RCP4.5 2071–2099 -14.64 -13.98 -14.03 19 HIRHAM5 RCP8.5 2041–2070 -13.87 -9.91 -10.99 16.79 HIRHAM5 RCP8.5 2071–2099 -9.96 -16.02 -13.94 22.78 RACMO22T RCP4.5 2041–2070 -7.14 -9.11 -8.19 16.05 RACMO22T RCP4.5 2071–2099 -14.59 -13.99 -14.04 19.01 RACMO22T RCP8.5 2041–2070 -13.72 -9.48 -10.31 16.68 RACMO22T RCP8.5 2071–2099 -9.31 -16.27 -13.51 22.69 RCA4 RCP4.5 2041–2070 -7.46 -9.73 -8.89 16.12 RCA4 RCP4.5 2071–2099 -14.85 -13.91 -14.02 19.02 RCA4 RCP8.5 2041–2070 -13.67 -9.63 -10.05 16.48 RCA4 RCP8.5 2071–2099 -9.34 -16.03 -13.71 22.47 CRCM5 RCP4.5 2041–2070 -7.84 -9.76 -8.82 16.07 CRCM5 RCP4.5 2071–2099 -14.48 -13.96 -14.07 19.01 CRCM5 RCP8.5 2041–2070 -13.92 -9.99 -10.82 16.75 CRCM5 RCP8.5 2071–2099 -9.51 -16.05 -13.78 22.69 REMO2009 RCP4.5 2041–2070 -7.55 -9.45 -8.73 16.09 REMO2009 RCP4.5 2071–2099 -14.72 -13.92 -14.01 19.02 REMO2009 RCP8.5 2041–2070 -12.56 -9.78 -10.54 16.68 REMO2009 RCP8.5 2071–2099 -9.52 -16.08 -13.75 22.67

Ensemble RCP4.5 2041–2070 -7.56 -9.44 -8.72 16.08 Ensemble RCP4.5 2071–2099 -14.71 -13.93 -14 19.01 Ensemble RCP8.5 2041–2070 -12.55 -9.79 -10.55 16.67 Ensemble RCP8.5 2071–2099 -9.53 -16.09 -13.74 22.66 https://doi.org/10.1371/journal.pone.0287314.t006 PLOS ONE The impacts of climate change on hydrological processes of gilgel gibe catchment PLOS ONE | https://doi.org/10.1371/journal.pone.0287314 June 28, 2023 20 / 28