ABSTRACT
The availability of freshwater at various spots on the Earth’s terrestrial surface will continue to be determined by the hydrological cycle, till such a time when technologies like desalination of seawater is practiced on a reasonably extended scale. The rapid growth in the demand of freshwater driven by growth in the global population and of the economies, has led to this natural resource becoming scarce in many parts of the world. As a result, the ratio between the number of people and the available water resource is worsening day by day. By 2020, the global population is projected to be in the range of 7.3 to 7.9 billion, which is 50 per cent larger than that in 1990 (UN, 2006). Because of this rapidly growing human population, the world may see more than a six-fold increase in the number of people living in conditions of water stress - from 470 million today to 3 billion in 2025 (Postel, 1999).
