Interesting. I had never thought about the implicit assumptions behind the term "water wars". I figured that just because I couldn't think of a significant example off the top of my head, I wasn't thinking hard enough.

I am confused by their figures, though. "If they were to be self-sufficient in food, they would need ten billion cubic metres of water per year. As it is, they have only about one-third of that: enough to grow 15-20% of their food." Ten billion would grow 100%, but a third of the water grows no more than a fifth of the food? It shouldn't be that some of the current water supply goes to other uses; a couple of sentences later is a note that domestic and industrial uses should find rainfall alone to be enough.

How would tripling the amount of water available allow them to increase domestic food production by five or six times?