Thursday, March 15, 2012
Are We Running Out of Water? by Brian Richter
A dry river near Darcha in India. Ankit Solanki, Flickr Creative Commons
Early in 2001, the Rio Grande River failed to reach the Gulf of Mexico for the first time.
With that nefarious event the Rio Grande joined a growing list of once-mighty rivers that are running dry from overuse: the Colorado River in the U.S., the Yaqui in Mexico, the Indus in Pakistan, the Ganges in Bangladesh, the Yellow and Tarim in China, and the Murray in Australia, along with many other rivers large and small.
Not surprisingly, fisheries in these once-bountiful rivers have crashed. After all, fish do need water.
We’ve tapped underground water sources pretty heavily as well. The water level in the Ogallala Aquifer in the Midwestern U.S. has dropped more than 150 feet in some places, leaving many farmers’ wells bone dry.
As water is sucked out of aquifers, the overlying soil and rock can compact or collapse into the dewatered void, causing tall buildings to teeter in Mexico City, automobiles to tumble into sinkholes in Florida, or swallowing tourists on the fringes of the shriveling Dead Sea in Israel and Jordan.
With so many rivers, lakes and aquifers going dry, we have to ask: Are we running out of water?
The Big Picture
The glass-half-full answer is no……. at least not at the planetary level. Today there is just as much water on the planet as there was when the first signs of life appeared.
Every year, about 110,000 billion cubic meters of water falls on the land surface of our planet as rain or snow. That annual endowment of water would cover all land to nearly a meter deep if it was spread evenly.
More than half of all of that water evaporates quickly or gets taken up by trees, shrubs, and grass.
More than a third flows out to the coasts, where it helps to maintain the delicate salt- and freshwater balance of estuaries, without which much of our seafood industry would collapse.
Of all the water falling on land, we’re consuming less than 10% to grow our crops, supply our homes, keep our industries running, and generate electricity.
Every bit of the water that falls on land or in the ocean or is used for human endeavors is eventually evaporated back up into the sky as water vapor, replenishing our planet’s never-ending freshwater cycle. No water is actually ‘lost’ in that global cycle.
So what’s the problem? Surely we can’t be in trouble if we’re depleting less than 10% of the Earth’s naturally renewable water, and the water cycle keeps bringing that water back year after year?
Here’s the catch: the water that falls from the sky isn’t evenly distributed around the globe, and our needs for that water aren’t the same everywhere.
So why can’t we just move water from places of abundance to places of shortage? Why can’t we take the fresh water flowing to the Arctic Circle and redirect it to the parched cities of the American Southwest?
Such plans have been on the drawing boards of big water dreamers for decades. In truth, the only thing that has stopped these initiatives is the fact that far less costly alternatives usually exist for meeting our water needs in the near term. We only have to look to the South-North Water Transfer Project in China for a bellwether of what may come. The Chinese will invest $62 billion to build a pipe-and-canal system to move water over hundreds of kilometers from the Yangtze River to parched cities and farms in the north. As the New York Times reported last year, “It would be like channeling water from the Mississippi River to meet the drinking needs of Boston, New York and Washington.”