Population..

Effects of population Growth....

Competition for water resources among individuals, regions, and countries and associated human activities is already occurring with the current world population. About 40 percent of the world's people live in regions that directly compete for shared water resources. In China where more than 300 cities already are short of water, these shortages are intensifying. Worldwide, water shortages are reflected in the per capita decline in irrigation used for food production in all regions of the world during the past twenty years. Water resources, critical for irrigation, are under great stress as populous cities, states, and countries require and withdraw more water from rivers, lakes, and aquifers every year. A major threat to maintaining future water supplies is the continuing over-draft of surface and ground water resources.

Diseases associated with water rob people of health, nutrients, and livelihood. This problem is most serious in developing countries. For example, about 90 per cent of the diseases occurring in developing countries result from a lack of clean water (Pimentel et al., 1996). Worldwide, about 4 billion cases of disease are contracted from water and approximately 6 million deaths are caused by water-borne disease each year. When a person is ill with diarrhea, malaria, or other serious disease, anywhere from 5 to 20 percent of an individual's food intake offsets the stress of the disease.