Mankind's Water Needs Require Search for Cost-Effective Resource Management

Article excerpt

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 suffice.

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. …