Computer simulations for drought-prone areas reveal that when urban water planners combine three approaches of buying water -- permanent rights, options and leases -- the city avoids surplus water and high costs, and reduces shortages, according to civil engineers.
"Just like with stock portfolios, if you buy diverse stocks, you diversify your risk," said Patrick Reed, associate professor of civil engineering, Penn State. "Right now, cities don't necessarily diversify their risk through the ways in which they buy water."