In the face of predicted water shortages and their rather over-hyped corollary–twenty-first century wars over water resources–the solutions of integrated management sometimes seem outweighed by the size of the difficulties to be overcome, if only because of the problems of putting into practice solutions which must be agreed between a number of countries with varied interests. Managing the needs of several countries, and often of several competing sectors in each one, on the scale of a catchment area, is no small undertaking, especially if there is a history of mistrust between the different governments. Modern civil engineering techniques prompt a fresh look at the possibility of diverting very large volumes of water originating far from centres of consumption over great distances.
Large-Scale Water Transfers: an Attempt at a Classification
The rapid growth of the need for water in the twentieth century and the advent of modern construction methods mean that projects for large transfers of water are once more being seriously considered in different parts of the world, to respond to increasingly critical situations. If water is scarce here, why not seek it where it is abundant? Grand projects for the diversion of fresh water are founded on this apparently simple question. Once built, aqueducts enable vast quantities of water to be transferred over great distances. The Soviets in Central Asia and the Americans have used this technique to move considerable volumes as a central element of their strategy to improve agricultural land, with canals from the Syr and Amu rivers for the former, and many canals in the Midwest and the West Coast, where the Colorado has become a major artery, for the latter. The argument as to the rationality of the use of water where the need exists has recently been joined by one over the moral necessity of aid from countries with abundant drinking water to regions lacking it. According to this argument, it would be immoral to refuse to export water to such regions. New and massive water export projects are flourishing in Newfoundland, Austria, Spain, France (the Rhône) and even Iran, where water supply is a major constraint. But what are the different techniques for large-scale transfer? And to what extent are all these projects based on the same rationale, that is, to satisfy a desperate need for water? Do other political, social and economic considerations influence the appeal which these projects sometimes present?
Large-Scale Transfer: Different Technologies at Different Scales
The techniques of large-scale transfers are part of the approach to water resource management ‘by offer’, which consists in increasing the quantity of water available when a shortage occurs. This category also includes increasingly effective desalination technologies such as reverse osmosis and, in the experimental stage, cloud seeding, towing icebergs and the collection of dew in giant nets. This approach is the opposite of ‘demand management’ which, rather than increasing the available quantity of water, consists in rationalising its use, based on the principle that shortage is a relative term. Better irrigation techniques, the location of leaks in supply channels, reduction in industrial wastage, more disciplined consumption habits by the population, charging and tax incentives, are all examples of measures which can be used in this form of management.
Water Tankers
Modified tankers can transport large quantities of fresh water over long distances. This system was used between Marseille and both Catalonia and Sardinia between 1983 and 1990.(1) The Canadian group Global Water Corporation (GWC) has been exporting 18.2 million cubic metres of fresh water annually from Alaska to a bottling plant in China since July 2001.
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