ABSTRACT
The ten years from 1981 to 1990 have been designated by the United Nations as International Water Supply and Sanitation Decade, in which an estimated $300 billion is to be spent on the provision of infrastructure, bringing new facilities to perhaps two billion people. The world seemingly faces a dichotomy in its provision, with overestimation of needs in areas of the West, and under-provision in many areas of the Third World. Tunisia, a country of some 6.6 million people, is usually regarded as forward-looking in its water supply management, although it lies at one end of the demand-management spectrum as the potential demand in some of its regions exceeds the supply capacity. Only 4.9 per cent of Tunisians had access to safe drinking water in 1970 and the situation has improved only slightly since. The social and environmental consequences of this demand suppression are very serious. This paper examines the situation in the arid far-south where desertification is threatened as a result of both groundwater mining and longer-term environmental changes. It seeks to make explicit constraints which affect the accuracy of demand forecasts and to explore interrelationships which make separate consideration of demand and supply impossible.
