New York Times: THE Earth may be two-thirds water, but only about 1 percent of that water is actually usable for human consumption and agriculture. What`s more, as the planet warms and the population shifts, even that 1 percent is at risk. That is why demand for hydrologists has been predicted to grow 24 percent from 2006 to 2016, much faster than the average for all occupations, according to the Bureau of Labor Statistics. Hydrologists study the distribution, circulation and physical …