Environmental Engineering Reference
In-Depth Information
period 1997-2001). If the importing countries were to have produced the imported prod-
ucts domestically they would have required a total of 1600 billion m
3
/yr. This means that
the global water saving by trade in agricultural products was 350 billion m
3
/yr. So the
average water saving accompanying international trade in agricultural products has been
(350/1600=) 22 percent. The global volume of water used for agricultural production is 6400
billion m
3
/yr. Without trade, supposing that all countries had to produce the products
domestically, agricultural water use in the world would amount to 6750 instead of 6400
billion m
3
/yr. International trade thus reduces global water use in agriculture by 5 percent.
The above
erentiate between the use of green water (rainwater) and
the use of blue water (ground and surface water). The global water saving associated
with a certain trade
fi
gures do not di
ff
ow can refer to either a global blue or a global green water saving
(or a combination of both). Even if there is a net global water loss from a trade relation,
there might be a saving of blue water at the cost of a greater loss of green water or vice
versa. From an economic point of view there is a substantial di
fl
erence between blue
and green water saving, because the opportunity costs of blue water are generally much
higher than the opportunity costs of green water. As a result, trade with an associated
blue water saving but a greater green water loss could still be e
ff
cient from an economic
point of view.
The downside of virtual-water import as a solution to water scarcity
Saving domestic water resources in countries with relative water scarcity through
virtual-water import (import of water-intensive products) looks very attractive. There
are, however, a number of drawbacks that have to be taken into account. First, saving
domestic water through import should explicitly be seen in the context of the need to
generate su
cient foreign exchange to import food that otherwise would be produced
domestically. Some water-scarce countries in the world are oil rich, so they can easily
a
ord to import water-intensive commodities. However, many water-scarce countries
lack the ability to export energy, services or water-extensive industrial commodities in
order to a
ff
ord the import of water-intensive agricultural commodities. Second, import
of food carries the risk of moving away from food self-su
ff
ciency. This plays an impor-
tant role in the political considerations in countries such as China, India and Egypt.
Third, import of food will be bad for the domestic agricultural sector and lead to
increased urbanization, because import reduces employment in the agricultural sector.
It will also result in an economic decline and worsening of land management in rural
areas. Fourth, in many water-scarce developing countries, where an important part of
the agriculture consists of subsistence farming, promoting food imports may threaten
the livelihoods of those subsistence farmers and reduce access to food for the poor.
Finally, increases in virtual-water transfers to optimize the use of global water resources
can relieve the pressure on water-scarce countries but may create additional pressure on
the countries that produce the water-intensive commodities for export. The potential
water saving from global trade is sustainable only if the prices of the export commodi-
ties truly re
ect the opportunity costs and negative environmental impacts in the export-
ing countries. Otherwise the importing countries are simply gaining from the fact that
they would have had to bear the cost of water depletion if they had produced domesti-
cally whereas the costs remain external if they import the water-intensive commodities
instead.
fl
