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Water, not food, the key to survival

Water, vital to life (© FAO)
Water, vital to life

Water, like the air we breathe, is essential to life but is usually taken for granted. During the past century, when world population increased threefold, water use increased six times. Investment in infrastructure - 40,000 dams built mostly in the past 50 years - provided abundant water at very little cost and contributed to the relatively low cost of food in most parts of the world. But, it also led to a degree of complacency and even wasteful use. As populations continue to grow, a greater proportion moves to cities and, as rising affluence increases expectations of diet and lifestyle, simply adding to the water supply is no longer an option.

Water that we drink (2-5 litres/person/day) and that we use for other domestic purposes (50-200 litres/person/day) is but a drop compared with that which we consume through the food we eat. To produce a single kilogram of wheat requires about 1000 litres of water; to grow a kilo of beef at least seven times as much - more than 7000 litres. This, says David Molden, Principal Scientist with the International Water Management Institute (IWMI), equates to the water in an Olympic size swimming pool to produce the food for one person's annual consumption.

A 'Blue Paper' titled Investing in Water for Food, Ecosystems and Livelihoods, drafted by Molden and Charlotte de Fraiture, was launched at World Water Week in Stockholm. The paper points to a number of options for improving the efficiency of water use in agriculture in the medium term. "If we can improve water productivity by 40 per cent over the next 25 years we'll be able to reduce the global need for extra water for irrigation to zero", says Frank Rijsberman, Director General of IWMI.

IWMI is coordinating the Comprehensive Assessment of Water Management in Agriculture (CAWMA), a five-year study now at its halfway point. Already some issues are clear: the main competition for water over the next century will be between agriculture and the environment, and a recent global study by IWMI researchers calculated that at least 30 per cent of the world's river flows need to be maintained to safeguard the viability and health of freshwater ecosystems. With water supplies finite, and demand from industry and growing conurbations increasing, increased demand for large-scale irrigation will not be viable. Indeed, it appears that the greatest prospect for increasing food production is from rain-fed agriculture where yields could be doubled with judicious supplemental water use, whereas the potential yield increase from irrigated agriculture is probably only 10-15 per cent.

Improving productivity

A major advantage of improving water productivity is that it would reduce the need for investments in new water withdrawals, investments that many countries cannot afford in terms of financial or ecosystem costs. Instead, the way forward is to manage water within river basins in an integrated way rather than the ad hoc approaches of the past. "There is a whole range of options for increasing the value that we get from the water used in agriculture", says Rijsberman. "In China they have improved the productivity of rice from half a kilogram that is normally produced from 1,000 litres of water to more than 2 kilograms of rice per 1,000 litres used. There are also several agronomic options: using no-till techniques, alternate wetting and drying, better soil fertility, and better management by farmer associations."

Water productivity can also be significantly improved by a better understanding of water flows in river basins so that upstream and downstream users are treated equitably. Simply conserving all possible water upstream can deprive downstream users - robbing Peter to pay Paul, as Rijsberman puts it - but there is potential for water harvesting and for reallocating water in a basin so that it is used to maximum economic benefit. For instance, when water is scarce it may be better for small farmers to use it to irrigate horticultural crops rather than have it used on vast areas of sugar cane. This can improve the value of the water used from cents to dollars per 1,000 litres. Moreover, the extra value would go to many small farmers, and produce crops of nutritional benefit. In support of this as a sensible option, research at Sokoine University, Tanzania by Reuben Kadigi has shown that small farmers on 0.1 ha are at least twice as productive in their water use as farmers on 10-100 ha.

It is clear that 'business as usual' is not an option and that complacency about water and food issues must be replaced by an awareness that water is a finite resource. Much improved management of water will be necessary if poverty and hunger are to be reduced and conflict avoided.

Date published: September 2004


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