There is increasing likelihood that by the early 21st century, water and not energy will claim the primary focus of world attention. There are substitutes for energy other than depleting fossil fuels in the form of renewable and non-conventional sources; none for water. Desalination remains energy-intensive and expensive, especially for large communities and if it requires pumping away from coastal neighborhoods.

Already, large parts of the world are beginning to feel the water crunch: North America, Australia, large parts of India and China, West and Central Asia and huge chunks of Africa, representing the larger half of humankind. Water is something people die for and nations go to war for. It is time to take notice and act to stave off a menacing crisis.

Sandra Postel brings together a large amount of useful information, not merely about how and where things have gone wrong, but also about what is being done about it. Only 2 per cent of the world's water is freshwater and only part of that is utilisable. The global population has grown from 2.6 to 5.4 billion during this century and threatens to double by the middle of the next. This is going to make enormous demands on production of water to quench the thirst of the growing millions, provide for expanding cities and industry and sustain a rise in the quality of life.

The first dictum
Conservation is clearly the first and most obvious answer and there is little doubt that very substantial savings at low unit cost are possible through improved use-efficiency, better management and new technologies. Irrigation is the largest water user and savings of 10 to 50 per cent are feasible in this sector. According to Postel, even more dramatic savings of 40 to 90 per cent are possible in industry through a variety of means.

The list is well known: better water and watershed management; more realistic pricing to reflect the scarcity value of water; reliance on water-user associations instead of large, impersonal systems; more scientific crop and land use planning; moderating run-off through afforestation and other means, and resort to more sophisticated systems such as sprinkler and drip irrigation. In the urban-industrial sector, recycling, reuse (with treated water being used for sewage irrigation) and redesigning of toilet systems to reduce flushing requirements, could provide the solutions. Merely seeking supply-side solutions will not work. All this makes good sense.

However, one is left with the feeling that Postel is perhaps turning a Nelson's eye to some of the problems. The projected increase of population is virtually going to be mostly in the Third World. Sprinkler and drip irrigation is certainly applicable here, but will take time because investments have to be made and infrastructure and management skills have to be developed. Moreover, though these systems are well-adapted to certain high-value crops, they are not suited to cereals like rice and wheat, which account for the largest acreage in developing countries.

Similarly, while existing surface irrigation systems may not be very efficient, seepage and application losses can be usefully recaptured through groundwater pumping. This, however, takes energy and overdrafts must obviously be avoided. Dryland farming technologies certainly need to be improved and crop research should bend towards producing more salt-tolerant strains. But these measures are going to take time and will have only an incremental effect.

Even then, there would still be a residual problem, which can be met only through large and small storages and transfers. While the rate of irrigation growth may have declined and the limits to large dams all but reached in North America, Postel's seeming generalisation from the West's turning away from this option is mistaken. The West can possibly afford to do so. Also, the bulk of the dam construction in the industrialised world is already over and they have technological and conservation options.

Most of the Third World is not similarly placed. The dam option simply cannot be foreclosed or relegated even as all the other prescribed strategies are pursued. Nor are small dams an alternative to large dams, as mistakenly supposed by many. In any event, these are not mutually exclusive. Again, while the plea for forest conservation and better land use is well taken, the relationship between deforestation and floods is overdrawn.

India's irrigation efficiency cries out for improvement. But the much recycled Rajiv Gandhi quotation about the lack of benefits from large projects -- "For 16 years we have poured money out. The people have got nothing back, no irrigation, no water, no increase in production, no help in their daily life" -- is not the first instance worldwide of prime ministerial effervescence.

The facts are otherwise. The Narmada critique of the World Bank's Independent Review Mission is flawed and has done little service to informed debate. Amendment of extravagant lifestyles, all-out efforts to limit runaway population growth and what Postel calls a "new water ethic" are all necessary. Last Oasis, however, consists of more than just demand conservation. Supply expansion is still vital in many parts of the world.