This study intended to estimate the potential evapotranspiration (PET) and crop water requirement (CWR) under climate change in Upper Wabe Bridge watershed. Precipitation and temperature data were projected using the mean of three Regional Climate Models (RCMs) derived by three General circulation models (GCMs) via Coordinated Regional Climate Downscaling Experiment (CORDEX) Africa of Representative Concentration Pathways (RCP4.5 and RCP8.5) scenarios. PET was computed by using the Hargreaves equation. The results confirm a variability of PET by interchanging of excess and deficit at all stations. The average annual PET slowly increases and becomes it's extreme on 2100 under RCP8.5 scenario at all stations. However, under RCP4.5, the PET's become high at the start of midterm, and then start to decline and reach its minimum value at the end of the long term. The rates of changes vary from 19.9 to 28.5% under RCP8.5 and, 14.3 to 15.3% under RCP4.5 at Kofele, and 11.8 to 6.8% under RCP4.5 and 16.3 to21.1% under RCP8.5 scenario at Sire station from midterm (2040–2070) to long-term (2071–2100), respectively. The annual average PET varies from 37.6 to 49.2% in RCP8.5, but decreases from 30.1 to 15.4% in RCP4.5 climate scenario at Kofele station. In Kiremt season PET decreases from the mid-2050s to long 2080s terms under both climate scenarios. The outcomes showed that CWR showed also a similar trend as PET. The increasing trends in PET will rise the irrigation water requirement and as a result, need to revise water resource development and water allocation policies in the watershed.

这项研究旨在估算上韦贝桥流域在气候变化下的潜在蒸散量（PET）和作物需水量（CWR）。降水和温度数据是使用由三个普通环流模型得出的三个区域气候模型（RCM）的平均值来预测的（GCM）通过代表性浓度途径（RCP4.5和RCP8.5）情景进行的非洲区域协调降尺度实验（CORDEX）。通过使用Hargreaves方程计算PET。结果证实了PET在所有站上的过量和不足的互换性。在所有站的RCP8.5情景下，年均PET缓慢增长并在2100年达到极限。但是，在RCP4.5下，PET在中期开始时就变得很高，然后开始下降，并在长期结束时达到其最小值。在Sof站，RCP8.5的变化率从19.9％降低到28.5％，在RCP4.5的变化率从14.3％降低到15.3％，在RCP4.5的情况下，变化率从11.8％降低到6.8％，在RCP8.5的情况下变化16.3％到21.1％从中期（2040-2070）到长期（2071-2100）。在Kofele站，RCP8.5的年平均PET值从37.6％下降到49.2％，但在RCP4.5的气候方案中从30.1％下降到15.4％。在两种气候情景下，基雷姆季节的PET排放量从2050年代中期减少到2080年代长期。结果表明，CWR也显示出与PET相似的趋势。PET的增长趋势将增加灌溉用水量，因此，需要修改流域的水资源开发和水分配政策。