But is this the same flood and fertility that sustained Ancient Egypt? There's no doubt that the White Nile has enough water and nutrients to completely transform the Sudd. But the great marsh holds onto its riches. It soaks up the water like a massive sponge and the labyrinth of papyrus traps any sediment. Despite a great influx of water, the flood goes no further North. The flow of the White Nile out of the Sudd changes little through the year. Ancient Egypt's desert world relied on the annual flood brought by the Nile. With it arrived millions of tonnes of fertile soil. So where did it come from? The search upstream from Egypt and then up the White Nile stalled at the Sudd. This branch of the Nile is not the source of the great flood. But there is an alternative, to return to Khartoum and take a different journey along the Blue Nile.


滋养古埃及的就是这洪水和丰饶吗？白尼罗河毋庸置疑地拥有能够完全转变苏德沼泽的丰足水量和养分。但沼泽地并不慷慨，它像巨大的海绵一样吸收了洪水，而迷宫似的纸莎草丛圈住了所有沉淀物。虽然水量非常丰沛，但洪水不会再北流，苏德之外的白尼罗河流域一整年都不会发生什么变化。古埃及人的沙漠世界仰赖尼罗河一年一度的洪水及其携带的百万吨肥沃土壤维生。那么它究竟来自何方？从埃及出发的溯源之旅沿着白尼罗河上溯到苏德沼泽，发现这条尼罗河的支流并不是泛滥的源头。但还有一个选项：返回喀土穆，选择另一条上溯青尼罗河的路线。