I'm currently flapping around the Internets, scavenging for articles suitable for my environmental science classes. The good news is, it's quite interesting; but the bad news is, much of what's interesting is behind pay walls, like that of AAAS. We're left with interesting teasers like this:Is Agriculture Sucking Fresh Water Dry? - ScienceNOW:
Agriculture accounted for about 92% of the world's water footprint, the researchers estimate. The water needed to grow so-called cereal grains such as wheat, rice, and corn accounted for about 27% of global water consumption; meat and dairy products accounted for another 22% and 7%, respectively. "Grain is the currency by which we trade water," Postel says.
Agriculture's huge water usage offers hope that humans can reduce overall water consumption, Hoekstra says. Improving the efficiency of irrigation, for example, will allow enhanced use of surface water derived from precipitation and reduce dependence on unsustainable withdrawals of groundwater. Each cubic meter of water that's drawn from surface sources, which are generally renewable, is a cubic meter that doesn't have to be pumped from aquifers. Such underground sources of water typically aren't considered renewable at timescales relevant for humans, he notes.