Saturday, 1 September 2012


When food is transported substantial volumes of
water flows within it. For every kg of food produced,
between 5 and 25 tonnes of water is used. Moving food
from areas with high water availability, and high water
use efficiency, to areas with scarcity or low productivity may result in considerable overall water savings.

Substantive amounts of water are
consumed as crops grow; each person requires 50 to 100
times more water to produce the food they eat than
they use in their home. One fundamental condition
for good yields is that the roots gain access to enough
green water to allow for an efficient photosynthesis.
This green water is a local resource that is available to
the farmer. To avoid crop water deficiency, blue water
from rivers or aquifers may be added by irrigation.
Farmers will have to compete for that water, since it
is the key resource for other societal functions, including water supply, industry and energy production.
Continued population growth in large regions with
limited rainfall will creates dilemmas in the future as
the competition for blue water escalates.

Finding the
best path for sustainable food production requires an
understanding of the resource requirements from cities, industrial use, energy production and for sufficient
environmental flow in the river to maintain healthy
habitats for freshwater and coastal aquatic ecosystems.
This calls for a shift in thinking that is based upon
sequential reuse along a river system.