Extreme hydrological events, like floods and droughts, exert considerable effects on both human and natural systems. The frequency, intensity, and duration of these events are expected to change due to climate change, posing challenges for water resource management and adaptation. In this study, the Soil and Water Assessment Tool plus (SWAT +) model was calibrated and validated to simulate flow under future shared socioeconomic pathway (SSP2-4.5 and SSP5-8.5) scenarios in the Baro River Basin with R2 values of 0.88 and 0.83, NSE of 0.83 and 0.74, and PBIAS of 0.39 and 8.87 during calibration and validation. Six bias-corrected CMIP6 Global Climate Models (GCM) were selected and utilized to investigate the effects of climate change on the magnitude and timing of hydrological extremes. All climate model simulation results suggest a general increase in streamflow magnitude for both emission scenarios (SSP2-4.5 and SSP5-8.5). The multi-model ensemble projections show yearly flow increases of 4.8% and 12.4% during the mid-term (MT) (2041–2070) and long-term (LT) (2071–2100) periods under SSP2-4.5, and 15.7% and 35.6% under SSP5-8.5, respectively. Additionally, the analysis revealed significant shifts in the projected annual 1 day, 3 day, 7 day, and 30 day maximum flows, whereas the annual 3 day and 7 day minimum flow fluctuations do not present a distinct trend in the future scenario compared to the baseline (1985–2014). The study also evaluated the timing of hydrological extremes, focusing on low and peak flow events, utilizing the annual 7 day maximum and minimum flow for this analysis. An earlier occurrence was noted for both peak and low flow in the SSP2-4.5 scenario, while a later occurrence was observed in the SSP5-8.5 scenario compared to the baseline. In conclusion, this study showed the significant effect of climate change on river hydrology and extreme flow events, highlighting their importance for informed water management and sustainable planning.

中文翻译：

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量化气候变化对埃塞俄比亚巴罗河流域水文极端事件的规模和时间的影响

洪水和干旱等极端水文事件对人类和自然系统产生相当大的影响。由于气候变化，这些事件的频率、强度和持续时间预计会发生变化，给水资源管理和适应带来挑战。在本研究中，对土壤和水评估工具 plus (SWAT +) 模型进行了校准和验证，以模拟巴罗河流域未来共享社会经济路径（SSP2-4.5 和 SSP5-8.5）情景下的流量，R2 值为 0.88 和 0.83 ，在校准和验证过程中，NSE 为 0.83 和 0.74，PBIAS 为 0.39 和 8.87。选择并利用六个偏差校正的 CMIP6 全球气候模型 (GCM) 来研究气候变化对水文极端事件的幅度和时间的影响。所有气候模型模拟结果表明，两种排放情景（SSP2-4.5 和 SSP5-8.5）的水流强度普遍增加。多模型集合预测显示，在 SSP2-4.5 下，中期（MT）（2041-2070）和长期（LT）（2071-2100）期间流量年增长率分别为 4.8% 和 12.4%，以及 15.7% SSP5-8.5 下分别为 35.6% 和 35.6%。此外，分析还显示，预计年度 1 天、3 天、7 天和 30 天最大流量将出现显着变化，而年度 3 天和 7 天最小流量波动与预测相比，在未来情景中并未呈现出明显的趋势。基线（1985-2014）。该研究还评估了水文极端事件的发生时间，重点关注低流量和高峰流量事件，利用每年 7 天的最大和最小流量进行分析。与基线相比，在 SSP2-4.5 场景中峰值流量和低流量均出现较早的情况，而在 SSP5-8.5 场景中观察到较晚出现的情况。总之，这项研究显示了气候变化对河流水文和极端流量事件的显着影响，强调了它们对于明智的水管理和可持续规划的重要性。