More precarious than you thought

The PWD of Tamil Nadu keeps a record of Observatory Wells in each district. A comparison of the current depth to August 2010 reveals interesting trends.

Let’s look at the absolute depths for the years 2010 and 2015 (bear in mind, the Y axis is depth in meters),



As is apparent, in 5 years, 27 of the 30 regions have shown an increase in depth. Or, depletion of ground water. The extent of depletion is uneven, but if we were to average it across the state, the depletion rate is 0.34 Meters per year!



The average rate of depletion, being as high as it is, still hides how bad the situation is. The depletion is uneven as one’d expect. But what’s shocking is that the Delta region of Kaveri, starting from Trichy downstream to Thanjavur and Thiruvarur have seen their ground water levels drop by 36.41%, 52.32% and 44% respectively. In just 5 years! Some other districts you’d suspect will have depleted their ground water, such as Salem, just shock you with the scale: 59%.

The district wise depletion in ground water in percentage terms over a 5 year period is,



Chennai, perhaps because the government made rain water harvesting mandatory, has not been as bad as some of the other places. Though, it’s still lost about 15% of its ground water in that period.

This is desertification of Tamil Nadu. There’s no other way to look at it. And this also means the delta districts will have to switch to something other than paddy as their primary crop as early as possible. Importing rice, surely, is cheaper. The state cannot afford a crop that requires standing water.

The impact of ground water depletion on soil fertility in the detla region and the impact of declining quality of water on health are aspects that require further study. Hopefully someone in the Tamil Nadu government or another research institution is doing that. Let’s hope that gets published and is accessible to lay readers.

Desalination on a massive scale within 5 years will be a necessity. Perhaps Madras’ brightest are better off working on these areas compared to adding another app to the sharing economy. Surely, this will have a large enough market for most VCs, even.

3 thoughts on “More precarious than you thought

  1. Saravana Kumar S

    The continuous intake of ground water will leave the earth a waterless desert. The under ground water is mostly used for our daily activities. The used water is let out unminding the health of the environment.The water which is taken from the under ground has to be refilled in some ways. One solution to refill the ground water is collect the rain water and send to the ground. But our state is not receiving rainfall throughout the year. So the stored rainwater under the ground may not be sufficient for all time.
    In this case an efficient solution is to purify the waste water or used water. The water that is taken out from the under ground is partly consumed for metabolism of the organism which are not retrievable. The rest of the water after purification can be sent to the under ground. By doing this the water level will never go down. The another important advantage is the used water will not pollute the environment. Combining this method with rain water harvesting method will make our life a heaven.
    Please support the above said technique to leave the earth a lovely place for the forecoming generations. Jaihind!!!!

  2. Ram

    I believe the situation is worser than the data suggests due to one more fact, which is water being pulled from deeper in the ground using borewells and after use, being let out at the ground level. For example if water is pulled out from a 400 feet borewell and used to irrigate a paddy field, the seepage of irrigated water will seemingly show improvement in the ground water level, but in actuality it would just be a shift in water from deeper in the ground to the upper levels.
    Also more than rainwater harvesting Chennai has benefited from movement of water from suburbs like Tiruvallur and chengalpet into the city using lorries. After the water is used, it is again let out into the drainage and some of that water also seeps into the ground. The drainage water is not returned to the suburbs.

  3. ck

    Prohibition will solve it all !!
    Clearly we let these idiots run loose. We deserve it, for not choosing right and organizing better.
    Let’s hope better sense will eventually prevail.

    This should be something that the now disbanded Planning Commission could have focused on. Atleast that was the premise of its establishment. Now with the Sloganeering PM we have, we can be assured that this will get attention on Twitter to last for a good hour or so.
    Ache Din !!

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