In the interesting blog The Learning Diary Of An Israeli Water Engineer, the author (known only as J) writes a post on how Egypt's has growing concerns about lack of water, and doesn't have enough to be able to irrigate and bring millions out of poverty.
Other problems mentioned are other countries where the Nile passes before Egypt, who want to make a wider use of the water, but are threatened by Egypt and Sudan, who made a pact to keep it mostly for their needs alone. And the lack of advanced technology to make the most of the water, so that an enormous amount of it evaporates.
In the middle east it always seems to be about either water or oil.
As most of Egypt's income is derived from tourism, and tourism will cease if there is a war, he speculated that war is unlikely. However, he also connects Egypt's policy and future military planning to water:
He mentions how Egypt is going to need to establish a military hegemony to maintain control of the water, although he doesn't completely cover why this is an inevitability.
Many of us live under the belief/assumption that the Nile provides Egypt with all they need or could possibly want. Apparently, we should assume less.
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