Virtual Water

One of the most worthwhile books I've read in the last few years is When The Rivers Run Dry: Water - The Defining Crisis of the Twenty-First Century (Fred Pearce, author). This is a book which challenges your understanding of water-resource issues through 311 pages of text. The book is very well written and is a primary source of information to which I refer my students in GEOL 1403 (Physical Geology), a Freshman-level course I teach at Austin Community College, Austin Texas.

From the book jacket, the author is described as follows: "Fred Pearce has been writing about water issues for over twenty years. A former news editor at New Scientist and currently its environment and development consultant, he has also written for Audubon, Popular Science, Time, the Boston Globe, and Natural History. His books include Keepers of the Spring, Turning up the Heat, and Deep Jungle.

Pearce is a journalist, not a scientist; but he writes cogently about matters of great importance to those of us who work with water resources. More importantly, he distills complicated information about groundwater and surface water into language that is easily understood by most readers, their academic backgrounds notwithstanding. He is, without question, an exceptional writer.

In Chapter 1 of When the Rivers Run Dry, Pearce introduces the concept of virtual water. In the simplest of terms, virtual water is all of the unaccounted-for water that is used to produce the goods and services that people everywhere demand. I'll let Pearce describe the concept:

Manufacturing the goods that we fill our homes with consumes a certain amount [of water], but that's not the real story either. It is only when we add in the water needed to grow what we eat and drink that the numbers really begin to soar.

Get your head around a few of these numbers, if you can. They are mind-boggling. It takes between 250 and 650 gallons of water to grow a pound of rice. This is more water than many households use in a week. For just a bag of rice. Keep going. It takes 130 gallons to grow a pound of wheat and 65 gallons for a pound of potatoes. And when you start feeding grain to livestock for animal products such as meat and milk, the number becomes yet more startling. It takes 3000 gallons to grow the feed for enough cow to make a quarter-pound hamburger, and between 500 and 1000 gallons for that cow to fill its udders with a quart of milk. Cheese? That takes about 650 gallons for a pound of cheddar or brie or camembert.

We enjoy the products, but we don't see all of the resources that factor into the manufacture of those products. Pearce's point is that western societies use a great deal of water to support their lifestyles, and the sum total of this amounts to what he calls our water "footprint." In Pearce's opinion (I don't disagree):

The water "footprint" of western countries on the rest of the world deserves to become a serious issue. Whenever you buy a T-shirt made of Pakistani cotton, eat Thai rice, or drink coffee from Central America, you are influencing the hydrology of those regions - taking a share of the Indus River, the Mekong River, or the Costa Rican rains. You may be helping rivers run dry.

Further on, he continues:

While many nations relieve their water shortages by importing virtual water, some exacerbate their problems by exporting it. Israel and arid southern Spain both export water in tomatoes. Ethopia in coffee. Mexico's virtual-water exports are emptying its largest water body, Lake Chapala, which is the main source of water for the second city, Guadalajara.

His point is that there is an imbalance in the accounting of the relative values of water and the goods that the water is used to manufacture. Think about it: 250 to 650 gallons of water to grow one pound of rice, and 3,000 gallons of water to grow the feed to produce the meat to make one quarter-pound artery clogger!

Because most consumers are far removed from the production of goods and services that require the use of water, they tend not to factor in the hidden cost of a resource such as water. Water, as such, is a free resource ... until it becomes scarce.

Best Regards,

aquadoc