China’s Hidden Water Footprint

COLLEGE PARK, Md. – Highly developed but water-scarce regions in China, such as Shanghai, Beijing, and Tianjin, are contributing to water depletion in other water-scarce regions of the country through imports of food, textile, and other water intensive products, according to a new study published in the journal Environmental Science & Technology. For example, purchasing cloth in Shanghai may not consume water directly, but the production of cloth requires cotton, which is water intensive to cultivate – indirectly contributing to the water scarcity in the less-developed cotton production regions. This dynamic also holds true for food and other products. Only 20% of Shanghai’s scarce water footprint, or the amount of scarce water consumed, is from local watersheds while 80% is from water resources of other water-scarce regions, such as Xinjiang, Hebei, and Inner Mongolia.

This disproportionate consumption of water by wealthier regions has environmental impacts and potential future impacts on water availability for the entire country.

The new study used the concept of “virtual water,” an economic concept used to track water flows through trade, to track how water is traded through agricultural products and other goods that require water to produce. But while previous virtual water studies had treated all water equally, the new study accounts for water scarcity to assess China’s hidden flows.

 “When goods and services are exchanged, so is virtual water,” explains University of Maryland and IIASA researcher Laixiang Sun, a study co-author. “For example, it takes about 1,600 cubic meters of actual water to produce one metric ton of wheat. When a country or region imports a ton of wheat instead of producing it domestically, it saves most of that.”

Huangpu river in Shanghai. Photo credit: Jakub Hałun (Source: Wikipedia)

Huangpu river in Shanghai. Photo credit: Jakub Hałun (Source: Wikipedia)

In China, water resources are distributed unevenly, with ample water in the wealthier southern region, and scarce water availability in most northern provinces. The study, titled Virtual Scarce Water in China, shows that trade between these water-scarce regions tends to draw more sharply on water resources in the less developed, poorer regions. For example, the highly developed provinces of Shanghai, Shandong, Beijing, and Tianjin import large amounts of virtual water at the expense of less-developed provinces such as Xinjiang, Inner Mongolia, and Hebei.

“This study goes beyond many other water footprint studies that it takes into account virtual water flows from water-scarce regions. This allows us to identify cases where importing water-intensive goods from other water-scarce regions may just shift the pressure to other regions. On the other hand we don’t need to worry about a large water footprint if the water is imported from water abundant areas. Previous studies often failed to account for this important difference,” says co-author Klaus Hubacek, a researcher at the University of Maryland.

The study also examined the impact of international exports on water resources, showing that production of international exports in China’s top exporting regions also draws on water resources in water-scarce northern provinces.

Dr. Feng, first author of the study, adds, “With the fast growth of China’s economy, and increasing urbanization, this trend is likely to continue in the next few decades.”

Recognizing the problem of water scarcity, China has launched a multi-billion dollar water transfer project to divert water from the South to the North. But the authors suggest that replacing production of water intensive products from the North with goods imported from the South could be a more efficient and sustainable solution to the problem.

The researchers suggest that the study lays the groundwork for smarter water resource management. Says Sun, “This is the first study that incorporates water consumption and flows, water scarcity, and ecosystem impacts into an analysis that conveys the pressures on water resources. Using virtual water as a policy tool only makes sense if you take water scarcity into account.”

*Source: University of Maryland

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