It's raining cats & dogs in chennai for the past few days. The monsoon has just set in and the weather news hits the headlines of every newspaper and news channels. Just take a look at this weather report and most of the weather news in the coming days is going to look the same.

"The following stations recorded very heavy to heavy rainfall in cms:-

Chennai and Ongole 19 each, Tiruvallur 18,  Cheyyur (Kanchipuram dt)  16, Redhills and Kakinada 13 each, Villupuram, Avinashi (Coimbatore dt), Erode, Ketti(Nilgiris), Cholavaram and Nellore 7 each."

Anyone with a basic knowledge in mathematics would say that chennai received more rainfall than Erode but how much of rain? What does 19 cms of rain measure to? Is it more or less? Let's find out.

Rain (Precipitation) is measured using a device called (Surprise!) "Rain Gauge". There are many varieties of rain gauges but the most popular are "Standard Bucket Rain Gauge" and the "Tipping Bucket Rain Gauge". I am not sure what kind of gauges the local met. dept. uses but I guess it should be the tipping bucket gauge because it was invented by the British. Since there are many websites that clearly explain the functioning of these rain gauges, there is no point in repeating the same here.

http://vortex.plymouth.edu/precip/precip3a.html

http://www.seed.slb.com/en/scictr/lab/engineer/index.htm

http://en.wikipedia.org/wiki/Rain_gauge

Let's come back to our basic question. What does 19 cms of rain equal to?

Rain is normally measured in inches or millimeters. 1 inch of rain is equal to 1 inch depth of water collected in the ground. If 1 acre of a land recieves 1 inch of rain it equals to 1,02,789 litres of water. 1 Sq Mile of land gets 65.78 million litres of water! Now Let's assume that the total area of chennai is 100 Sq.Km. If the whole of chennai receives 1 inch of rain it gets

100 sq.km = 38.6 sq.miles

Total Water = 38.6 * 65.78 = 2.5 Billion litres of water.

Yesterday chennai received 19 cms of rain which is equal to 7.4 inches. So the total amount of water received is 18.5 billion liters of water!!!!!! Very Scary. I lost count on the number of zero's in  18 billion :D .Most of the water are sucked into the ground but I guess a major portion of them are wasted and diverted into the sea.

I am now able to fully appreciate the rain water harvesting scheme. Analysts have predicted that in the future war would be fought over water. If we could save all these water I guess there would be no shortage of water in the distant future. 

It's time to think and act and save all the water that is being wasted.