China's South-North water transfer is "irrational"
By Tom Levitt
August 27, 2012
Ruth Matthews, of the Water Footprint Network, tells Tom Levitt how food
has come to dominate our water use and why China may need to re-think
its South-North water transfer project.
See also: 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 The blue water footprint is water that has been withdrawn from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
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
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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