WATER is an essential "common good" that until fairly recently
was thought to be superabundant, and therefore used wastefully,
especially in the wealthy industrialized nations.
But in reality water is a relatively scarce resource: extremely
scarce in some parts of the world. And as the world's population
grows and its standard of living gradually rises, the demand for
water, and therefore its cost, is bound to increase.
Taking into account possible climate changes, the
already-difficult water problem can only get more complicated.
Since every increase of 1 degree centigrade in average temperature
moves the temperate latitudes 100 or 200 kilometers (62 to 125
miles) farther away from the equator, the areas where farm
productivity is now highest could eventually become semiarid or
arid, with drastic consequences for world food production.
Of course, large-scale projects will always be needed to
transport fresh water from places where it abounds to places where
it does not. In addition, cost-effective ways must be found to
exploit new water resources: by desalinating seawater, for
instance, and purifying polluted water. But more to the point are
small-scale actions that, with relatively small investment, can
promote conservation of this precious resource.
Sound water management starts with land-use and watershed
management. Drainage must be designed to collect runoff, especially
from torrential rains that lead to erosion and landslides. The
creation of adequate vegetation cover, irrigation systems, and
small interlinking ponds makes it possible to store water against
dry seasons and prevent erosion.
Another aspect is the modernization of water treatment,
recycling wherever possible and always aiming to prevent waste.
Cascade use must be properly managed: in geographical terms, from
higher to lower localities; in pollution terms, from lesser to more
contaminating uses; in terms of priorities, taking adequate account
of each country's typical needs, from domestic uses to farming,
power generation, and industry.
A `software' approach
Accordingly, water-management strategies need to take a
"software" approach, emphasizing the intangible and system
organization. This implies a complex process made up of many
different steps, relatively inexpensive and simple enough in
themselves, but conceived as parts of a whole system and
implemented from the bottom up. Naturally, large projects and
costly solutions will still be needed where "soft" actions do not
Today, agriculture accounts for around two-thirds of all the
water consumed worldwide. With the population growing steadily, it
would be unthinkable to try to limit world food production or farm
productivity. Irrigation, together with fertilizers and pesticides,
is the principal means of increasing farm productivity, and in the
past few decades it has been instrumental in fighting hunger in the
third world, especially in Asia.
In 1900, 40 million hectares (99 million acres) of the world's
farmlands were irrigated. By 1950 the figure had grown to 95
million hectares (235 million acres); by 1980 it was more than 200
million (494 million acres). During the 1980s the expansion of
irrigation slowed, in some cases because of the appearance of
symptoms of aquifer depletion, and in others due to the shelving of
new irrigation projects that lost out to industry and cities in the
growing competition for scarce water resources. …