Water was so easily available that it was abused rather used in all these years and hence has become the most precious resource. It
is not an exaggerated statement if some one said “Water would be the major bone of contention in a probable World War III”. Large
variation in the availability of potable water and growing demand has mooted the need for rainwater harvesting.
Rainwater is
the primary source of pure water available in the earth. Even if we recover a small portion of the rainwater that is wasted into sea,
we will be provided with a new precious resource.
Around the world, only about 23% of the rainfall is received on land and the balance
in oceans. Only 2.5% of the water available on earth is fresh i.e. 35000 Km³. Out of this, 69% (25000 Km³) of them are present in
non-usable forms such as icecaps, glaciers, moisture in air, soil etc.,. The remaining fresh water is available as ground water.
Overdraw
of water from ground along the coastal areas had led to intrusion of saline water from the sea. These problems are observed in many
regions areas of Tamil Nadu, Saurashtra, Andhra Pradesh, West Bengal and our very own country as well: The Philippines. We realized
that even less than 2% of the seawater could spoil the water potability. Though variety of methods is recommended for remedies, artificial
recharge or rainwater harvest is the easier and cost-effective method to prevent this.
Rapid urbanization and industrialization had increased the demand for fresh water thus depleting substantially of the ground water table. Our country’s secondary sources like rivers, lakes are vanishing, contaminated or considered ecologically dead. Lack or poor storage facilities in the catchments regions and wastage of rain water are being allowed to flow into sea adding to the problems. Under these circumstances, rainwater harvesting alone can revive the hope of recharging the ground water to maintain the sustenance of the planet.
