It's probably more complex than that, with more geopolitical factors involved. Right now, for example, Russia's political economy is limited by access to year-round deep water ports. China's relationship to Tibet is shaped by the fact that Tibet is basically China's watershed. The bread basket of the United States is just a bunch of fertile soil, blown off the Rockies, that happens to have landed underneath fantastic weather for corn, or wheat, or what have you. When any of those change, we're all going to become much more intimately familiar with the phrase "balance of power."

It's not going to be a case of moving near fresh water. It's going to be a case of getting tolerable living conditions subject to the political apparatuses and distribution networks that develop in response to the power structures that develop as the planet changes underneath the map and the map changes underneath our feet.

Good luck!