Prof (Dr) Sohan Raj Tater
IN a world of unpredented wealth, almost two million children die-each year for want of a glass of clean water and adequate sanitation. Millions of women and young girls are forced to spend hours collecting and carrying water, restricting their opportunities and their choices. Water – bone infectious diseases are growing in same of the world’s poorest countries. Human development reports 2006 investigates the underlying causes and consequences of a crisis that leaves 1.2 billion people without access to safe water and 2.6 billion without access to sanitation. In 2006 the International Management Institute, reported that water scarcity affected a full third of world population.
In 2007 the Interogovernmental panel on climate change predicted that due to climate change, the number of people facing water scarcity would grow. Other, too, say that there is a global water crisis, the availability of water is dwingling, the world is running out of the water.
Water scarcity is expected to become an even more important problem than it is today. There are several reasons for this :
* First the distribution of precipitation in space and time is very uneven, leading to tremendous temporal variability in water resources worldwide (Oki et al. 2003). For example, the Atacama Desert in Chile receives imperceptible annual quantities of rainfall whereas Mawsynram, Assam, India receives over 450 inches anually. If the fresh water on the planet is divided equally among the global population, there would be 5,000 to 6,000 M3 of water available for everyone, every year.
* Second the rate of evaporation varies a great deal, depending on temperature and relative humidity, which impact the amount of water available to replenish ground water supplies.
The combination of shorter duration but more intense rain fall (meaning more run off and less infiltration) combiled with increased evapotranspiration (the sum of evaporation and plant transpiration form the earth’s land surface to atmosphere) and increase in irrigation is expected to lead to ground water depletion.
(To be concluded)
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