When construction of the Grand Ethiopian Renaissance Dam (GERD) is completed, the Nile will have two of the world’s largest dams—the High Aswan Dam (HAD) and the GERD—in two different countries (Egypt and Ethiopia). There is not yet agreement on how these dams will operate to manage scarce water resources. We elucidate the potential risks and opportunities to Egypt, Sudan and Ethiopia by simulating the filling period of the reservoir; a new normal period after the reservoir fills; and a severe multi-year drought after the filling. Our analysis illustrates how during filling the HAD reservoir could fall to levels not seen in recent decades, although the risk of water shortage in Egypt is relatively low. The new normal will benefit Ethiopia and Sudan without significantly affecting water users in Egypt. Management of multi-year droughts will require careful coordination if risks of harmful impacts are to be minimized.

大埃塞俄比亚文艺复兴大坝（GERD）的建设完成后，尼罗河将在两个不同的国家（埃及和埃塞俄比亚）拥有世界上最大的两个水坝，即高阿斯旺水坝（HAD）和GERD。这些大坝将如何运作以管理稀缺的水资源，目前尚未达成共识。通过模拟水库的注水期，我们阐明了埃及，苏丹和埃塞俄比亚的潜在风险和机遇；一个新的正常贮存填充后段; 灌装后出现严重的多年干旱。我们的分析表明，尽管埃及的缺水风险相对较低，但在填充HAD水库的过程中如何将其降至近几十年来未见的水平。在新常态将使埃塞俄比亚和苏丹受益，而不会显着影响埃及的用水户。如果要使有害影响的风险最小化，多年干旱的管理将需要仔细的协调。