Monday, June 02, 2008

Water Footprints and Virtual Water

Between increasing agricultural demand and changing climate patterns, water resources are increasingly coming under stress. Countries such as India and China pump more water for agriculture than is replenished. China has effectively run out of water. The Yellow River rarely reaches to the sea anymore, while hundreds of villages have had to relocate because their water supply disappeared. Indian farmers pump 250 cubic kilometers of water a year for irrigation while only 150 cubic kilometers is replaced by rainfall. In Australia, six years of drought have eliminated most of that countries ability to export foods. In the U.S. Southwest, a rapidly growing population combined with decreasing rainfalls has created great stress over the distribution of water supplies.

In order to get a better idea of the world’s water use, the concept of the water footprint was introduced in 2002 as a way of measuring the total volume of fresh water used to produce the goods and services consumed by a nation. The water footprint includes the water content of goods imported into the country minus goods exported. Water used to produced goods for export is called virtual water. Major water exporters include The United States, Canada, Austria, Argentina, and Thailand. Major importers of virtual water include Japan, Sri Lanka, Italy, South Korea, and the Netherlands. Trade in virtual water is estimated to be around a thousand cubic kilometers a year—the equivalent of 20 river Niles. Much of this trade is going to the wealthy nations from countries that are over pumping their ground water.

India and China and the U.S. have the largest water footprints, consuming 13%, 12%, and 9% respectively of the world total. The U.S. has the largest per capita footprint, at 2480 cubic meters of water per person per year, more than three times that of India and China. A major factor contributing to the U.S.’s high per capita foot print is its high level of meat consumption. One hamburger, for example, requires 2400 liters of water to produce. A pair of leather shoes uses 8000 liters. On the other hand, a slice of bread only requires 40 liters.

Climate change and overuse of ground water are impacting the water footprints of some countries. The amount of the earth’s surface that is suffering drought has more than doubled in the past 30 years, partially the result of rising temperatures. Severe droughts have plagued both in China and Australia. Before its six year drought began, Australia was a major rice exporter. Now its rice crop has declined by 90%. India, China and Pakistan pump an estimated 400 kilometers of water a year from the ground, about twice the amount that is replenished by rainfall. Even as India depletes its aquifers, it remains a major exporter of water, through its food exports.

At the same time, fresh-water consumption worldwide has more than doubled since World War II to nearly 4,000 cubic kilometers annually and set to rise another 25 percent by 2030, says a 2007 report by the Zurich-based Sustainable Asset Management group investment firm. Up to triple that is available for human use, so there should be plenty, the report says. But waste, climate change, and pollution have left clean water supplies running short.

India, which faces some of the worst water shortages, and which is still a net exporter of virtual water, has adopted some of the most innovative ways to increase its water supply by harvesting rainwater. India’s monsoon weather results in large amounts of evaporation and runoff so India has returned to an age old practice of harvesting the rainwater. By adopting the very simple technology of harnessing rainwater, some villages have solved the perennial problem of drought.

The village of Rajsamadhiya has used rainwater harvesting to turn a near-desert landscape with empty wells into a land of trees and ponds, full wells and abundant crops. While other nearby villages rely on government water tankers to provide drinking water, Rajsamadhiya has been self sufficient for more than 10 years.

Rajsamadhiya is an example for the rest of the world which will have to face the consequences of resource exhaustion. They have found their salvation in simple, energy efficient technologies, resurrected from older times and implemented on a community level. Less and local has rewarded them with a new abundance of food and prosperity.