The construction of the Grand Ethiopian Renaissance Dam (GERD) on the Nile River has triggered much debate between Ethiopia, Sudan, and Egypt on the dam's effects. Once completed, the GERD will be Africa's largest hydropower plant. This study analyzes the implications of cooperative long-term operation of the GERD for Nile riverine flooding downstream of the dam. A daily river system model of the Eastern Nile is developed and used to examine how cooperative long-term operation of the GERD would affect the occurrence of three flood alarm levels (alert, critical, and flooding) in Sudan downstream of the dam. A reconnaissance-level flood inundation model is developed for the Nile within Khartoum State (Sudan's capital) to assess the GERD's impacts on the flood extent in the state based on simulated flows from the river system model. Assuming the GERD is operated to achieve a 90% power reliability and active upstream-downstream data sharing between Ethiopia and Sudan on the dam's daily outflows, results show that the GERD would reduce the occurrence of the three alarm levels. Based on 34 simulated river flow sequences, the proportion of years with at least one flooding alarm day at Khartoum Gage declined from 37% without the GERD to 11% with the GERD. Seasonal coordination and planning between Ethiopia and Sudan are necessary to mitigate the remaining riverine flood hazard. Although cooperative long-term operation of the GERD could play a positive role in reducing the riverine flood hazard in Sudan, the associated river flow alterations would adversely impact recession agriculture and the environment.

中文翻译：

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大埃塞俄比亚复兴大坝的合作运营减少了尼罗河洪水

尼罗河上埃塞俄比亚复兴大坝（GERD）的建设引发了埃塞俄比亚、苏丹和埃及之间关于大坝影响的争论。建成后，GERD 将成为非洲最大的水力发电厂。本研究分析了 GERD 长期合作运营对大坝下游尼罗河洪水泛滥的影响。开发了东尼罗河的日常河流系统模型，并用于研究 GERD 的长期合作运行将如何影响三个洪水警报级别（警报、严重和洪水）的发生。) 在苏丹大坝下游。为喀土穆州（苏丹首都）内的尼罗河开发了侦察级洪水淹没模型，以根据河流系统模型的模拟流量评估 GERD 对该州洪水范围的影响。假设运行 GERD 以实现 90% 的电力可靠性和埃塞俄比亚和苏丹之间关于大坝每日流出量的主动上下游数据共享，结果表明 GERD 将减少三个警报级别的发生。基于 34 条模拟河流序列，至少发生一次洪水的年份比例Khartoum Gage 的警报日从没有 GERD 的 37% 下降到有 GERD 的 11%。埃塞俄比亚和苏丹之间的季节性协调和规划对于减轻剩余的河流洪水危害是必要的。尽管 GERD 的长期合作运营可以在减少苏丹的河流洪水灾害方面发挥积极作用，但相关的河流流量改变将对衰退的农业和环境产生不利影响。