الفهرس 
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Abstract
1.1. Use of water:
As a prelude to discussing water resources, quality and pollution, it is important to appreciate the use of water and the demand for a satisfactory quantity and quality. The total quantity of water supplied to domestic consumers not only reflects the population but also the climate and standard of living of the community. Fur- thermore, variation in water demand occurs due to diurnal, annual or seasonal activities or by long term alterations in population sizes or living standards. Table (1) gives examples of demands related to climate and standard of living (Jackson et al, 1989).
1.2. Water Resources:
1.2.1. Hydrological cycle:
The hydrological cycle (Fig. 1) (Jackson et al, 1989) encompasses the movement of water in its various forms and phases over the surface and in the ground including behaviour when in contact with matter in the ground. When vapour evaporates from the oceans and is carried by the atmosphere until various thermodynamic.