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China's South-North water transfer is "irrational"

Tom Levitt

Readinch

Ruth Matthews, of the Water Footprint Network, explains how food has come to dominate our water use and why China may need to re-think its South-North water transfer project. 

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Ruth Matthews is executive director of the Water Footprint Network

See: Water transfer projects "essential" says Chinese scientist

Tom Levitt: What do you mean by our water footprint?

Ruth Matthews: A water footprint generally breaks down into three components. The green water footprint is the water that is used by plants from rainfall that has not run-off the soil and is taken up by crops. The blue water footprint is water that has been withdrawn from surface or groundwater and used in industry or agriculture. The grey water footprint is the amount of water necessary to dilute polluted water to meet water-quality standards. 

TL: Which sector has the highest water footprint?

RM: Agriculture has the highest water footprint, accounting for 92% of the blue water footprint. You might have heard figures of 70% to 72% for agricultural withdrawals of water, but what we’re looking at is the water that is actually consumed and including green water footprint, which explains why agriculture uses up more than 90% of the water footprint of humanity. 

Industry may withdraw a significant amount of water but a good proportion of that is not evaporated or incorporated into the product and is just returned to the source. For example, power-generation stations use cooling water but that water is not lost or consumed. Whereas water taken up by plants and evaporated or incorporated into, for example, a juicy watermelon, is now unavailable for other uses.

TL: Can you explain the problem of meat and its high water footprint?


The Water Footprint Network estimate that the average water footprint per calorie for beef is 20 times larger than for cereals and starchy roots. With the biggest contribution coming from growing their feed. In the US, for example, 68% of the grains produced are used for animal feed.


RM: There has been a study done, specifically in China, looking at how as the economic wealth of people grows, the consumption of meat is rising even more quickly. What that means is there is more pressure to either produce internally or to import meat products. Meat is a very high consumer of water, especially if you consider what is going into the feed. In some cases that feed is natural grassland and rainfed so the amount of water that is being put into it is not necessarily having an impact on the blue water resources. But if we are using that rainfall to grow soybeans to be eaten by cows to create beef, then we are getting less protein out of that rainfall than if we grew soybeans that were then eaten directly for their protein source. We are creating an additional food inefficiency in our food system.

TL: How are water scarcity issues likely to impact on us?

RM: The reality is that developed countries significantly externalise their water footprint. For example 42% of Europe’s water footprint is overseas. In some European countries the figure is even higher. What that means is that there is a relationship between the citizens of the EU and river basins around the world. 

As a country looks at how it manages its own water resources, you could suggest that it has the same responsibility to help the management of water resources in other river basins and meet those high standards of protection. In developing countries where there is less strict regulation, less capacity for monitoring and enforcement of those regulations the agriculture is done in such a way that there isn’t much protection for water. 

Countries like China and the US are in an interesting situation as they have a significant amount of natural resources themselves because they are such large countries. The amount of water the US imports and exports is fairly close, so it is putting a burden on other countries but is also relieving the burden because it is exporting goods, such as wheat.



TL: What are your views on China’s water footprint?

RM: What’s interesting in China is that for various reasons, including political, they have developed a lot of the agriculture in the north where it’s relatively water scarce. Within the country there is now a virtual water trade from the north to the south, which is fairly water rich. They are overtaxing water resources in the water-scarce north to transfer food to the water-rich south. 

And now they are looking at doing a massive water transfer from the south to the north to help support Beijing’s water and also to provide water to agriculture that is in the north. From an economic and environmental sense it’s irrational. It doesn’t make sense to push your agriculture in the north when you’ve got a lot of water in the south but this is how the situation is there now. 

As China’s population grows they are looking at more dependency on external water resources. So as well as looking at their internal water footprint, they have an opportunity to either take the proactive step of helping those countries where they are reaching out to use water resources in a sustainable and equitable way or instead contribute to the continual degradation of the river and groundwater ecosystems.

See: Water transfer projects "essential" says Chinese scientist

TL: What can we learn from water footprints?

RM: One of the things we can do with our water footprint assessments is to understand how water is being used within individual river basins and how that relates to the amount of water that is available and the amount that needs to stay in the river or aquifer to sustain biodiversity, ecosystem services and subsistence uses of water. What we see is that in certain times of the year in many river basins, because the amount of water that is available is less than is being used for agriculture and other uses, you see high water scarcity. 

One of the things we can do to improve food security is to really make the most and smartest use of green water resources. We can take some of the pressure off our blue water sources – lakes, river and aquifers – by increasing the efficiency of our use of rainfall and so reduce the green water footprint. This means that we are producing more food with less rainfall and by doing that you can also reduce the amount that you are dependent on those blue water resources.

If you look at the amount of green and blue water footprints needed for growing cotton in places all over the world what you see is that the countries around the Aral Sea in general require a much higher blue water footprint than other places because there is so little rain. The result has been the virtual disappearance of the Aral Sea and loss of fisheries from a massive growth in irrigated agriculture. So if you are going to be growing a very water thirsty crop, which cotton is, a really smart thing to do is to grow it in places where there is a significant amount of rainfall - reducing your reliance on blue water resources to the smallest amount possible.

TL: What are the best solutions to reducing our water footprint?

RM: For the private sector it is for there to be accountability in supply chains. So if a company like Unilever is selling all different types of products, they are not just looking at their operational footprint but also the water footprint in their supply chain, making sure that they are taking action to improve the sustainability and equitability of that footprint. In the public sector, it would be for the government to bring water footprint accounting into the mix of what they track, in the same way as they record GDP and trade exports and imports. 

Water footprint accounting can help them understand how water is used within the country – the sectors using it and the products produced as well as their economic value. Furthermore, how much water they are importing through virtual water flows and the value of that and how they are connected to water scarcity and pollution hotspots both within the country and externally.


Tom Levitt is managing editor at chinadialogue

Homepage image by Water Footprint Network 

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like this article

informative, short, precise and easy to understand. Thanks!

喜欢这篇文章

这篇文章信息量大、精简准确且通俗易懂。十分感谢!


水足迹是不合理的,已被多数专家摒弃

在对水资源管理的分析上,水足迹测量法已经被广泛认为不连贯并且存在技术缺陷。本质上来说,该方法大范围地比较了不同情形下的用水,但没有考虑到这些情形的差异。

因此通过一个更加可靠的方法对南水北调工程的影响进行分析后,结果表明,即便将其造成的环境影响考虑在内,南水北调也在整体上造福于中国社会。这个结论非常有趣。

比起真正为政策讨论提供数据,坚持水足迹的这些人好像更热衷于推销他们的这种测量方法。

water footprints are irrational and dismissed by most experts

The water footprint methodology has been widely dismissed as an incoherent and technically flawed approach to the analysis of water management. In essence, it compares water use in widely different contexts without considering the differences between them.

So it is interesting that a more technical analysis of the impact of the south north transfer indicates that it generates net benefits to Chinese society overall, even when considering its environmental impacts.

It seems that the water footprint community is more interesting in selling its approach as a service to corporate users than truly informing the real policy debates


不能仅将灌溉用水视为浪费而摒弃

灌溉用水一部分会留在土壤中,一部分会渗入地下水层,一部分会蒸发到空气中增加当地的环境湿度。如果中国西北地区没有灌溉,沙漠化很可能会更严重。诚然,农业用水可以直接转而供工业和居民生活使用,以避免南水北调,然而这样做要付出的代价就是沙漠化。

作者的观点似乎是:中国的南水北调工程不合理,是因为加速沙漠化是个更好的选择。

Irrigation should not be simply disregarded as wasteful

Some of water used for irrigation remains in soil, some enters groundwater aquifer, some evaporates and added moisture in the local environment. Without irrigation in northwest China, the desertification will likely get much worse. It is true that you can simply divert the agricultural water to industrial and residential uses and avoid the project of South-North water transfer. The cost of that, is desertification.
The author's argument appears to be: China's South-North water transfer is "irrational", because increased desertification is a better choice.


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