Abstract This study assesses the impact of climate change on water resources in the Upper Blue Nile (Abay) River Basin using a regional climate model (RCM), COSMO Climate Limited-area Model (CCLM), coupled with a hydrological model, Soil and Water Assessment Tool (SWAT). The SWAT model was calibrated and validated using measured streamflow data from four gauging stations. Climate change projections showed increases in mean annual temperature and decrease in precipitation in most parts of the Basin. Such changes are expected to affect the hydrologic regime of the Basin; these were assessed by running the SWAT model with the past (1981–2010) and future (2010-2039, 2040-2069 and 2070-2099) climate scenarios. The results show an increase of potential evapotranspiration (PET) by up to 27% by the end of the 21st century under RCP8.5 compared to the baseline period. Surface runoff is projected to increase by up to 14%. However, the increase in surface runoff could not increase the total water yield of the Basin. Instead, the total water yield of the Basin is estimated to decrease by -1.7 to -6.5% and -10.7 to -22.7%, for simulations forced by RCP4.5 and RCP8.5 scenarios, respectively. By the end of the 21st century, the contribution of baseflow to the total water yield of the Basin is also projected to decline to 11.4% from 41.3% during the baseline period. The decrease in baseflow partly explains the decline in the total water yield of the Basin. Such changes in the hydrologic balance will have significant implications for water management in the Basin.

中文翻译：

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气候变化对埃塞俄比亚上青尼罗河 (Abay) 河流域水资源的影响

摘要 本研究使用区域气候模型 (RCM)、COSMO 气候有限区域模型 (CCLM) 以及水文模型、土壤和水，评估气候变化对上青尼罗 (Abay) 河流域水资源的影响。评估工具 (SWAT)。SWAT 模型使用来自四个测量站的测量流量数据进行校准和验证。气候变化预测显示，该流域大部分地区的年平均气温升高，降水减少。预计此类变化将影响盆地的水文状况；这些是通过在过去（1981-2010 年）和未来（2010-2039 年、2040-2069 年和 2070-2099 年）气候情景下运行 SWAT 模型来评估的。结果表明，在 RCP8 下，到 21 世纪末，潜在蒸散量 (PET) 增加了 27%。5 与基线期相比。地表径流预计将增加 14%。然而，地表径流的增加并不能增加流域的总产水量。相反，对于 RCP4.5 和 RCP8.5 情景强迫的模拟，估计盆地的总产水量分别下降 -1.7 至 -6.5% 和 -10.7 至 -22.7%。到21世纪末，基流对流域总产水量的贡献预计也将从基线期的41.3%下降到11.4%。基流的减少部分解释了流域总产水量的下降。水文平衡的这种变化将对流域的水管理产生重大影响。地表径流的增加并不能增加流域的总产水量。相反，对于 RCP4.5 和 RCP8.5 情景强迫的模拟，估计盆地的总产水量分别下降 -1.7 至 -6.5% 和 -10.7 至 -22.7%。到21世纪末，基流对流域总产水量的贡献预计也将从基线期的41.3%下降到11.4%。基流的减少部分解释了流域总产水量的下降。水文平衡的这种变化将对流域的水管理产生重大影响。地表径流的增加并不能增加流域的总产水量。相反，对于 RCP4.5 和 RCP8.5 情景强迫的模拟，估计盆地的总产水量分别下降 -1.7 至 -6.5% 和 -10.7 至 -22.7%。到21世纪末，基流对流域总产水量的贡献预计也将从基线期的41.3%下降到11.4%。基流的减少部分解释了流域总产水量的下降。水文平衡的这种变化将对流域的水管理产生重大影响。到21世纪末，基流对流域总产水量的贡献预计也将从基线期的41.3%下降到11.4%。基流的减少部分解释了流域总产水量的下降。水文平衡的这种变化将对流域的水管理产生重大影响。到21世纪末，基流对流域总产水量的贡献预计也将从基线期的41.3%下降到11.4%。基流的减少部分解释了流域总产水量的下降。水文平衡的这种变化将对流域的水管理产生重大影响。