What data says about the Ground water situation in India, Karnataka and Tamil Nadu
November 18, 2022 Vaidya R
The Ministry of Jal Shakti, Government of India, recently published the report – National Compilation of Dynamic Ground Water Resources of India – 2022. This report details the state of groundwater extraction across India at state, district and district blocks (Taluks) level.
The report identifies the amount of water that recharges the groundwater reserves annually at each place in different seasons and computes the amount of water that can be sustainably extracted. It then notes the actual extraction of groundwater in that area and classifies those areas accordingly.
Based on this classification, if the extraction is less than 60% of the annual extractable amount, the stage of extraction in the area is considered “Safe”. If the extraction is between 60% and 90%, the state of groundwater extraction is considered “Semi-critical”. An extraction of 90-100% of the extractable amount classifies an area as “Critical”. Extracting more than 100% of the annual extractable amount classifies an area as “Overexploited”
How could a place extract more than the amount of water that goes in? This is where the concept of “Fossil Water” comes in. This is the water that is already there as groundwater in an area. This could be from rainfall from previous years which were not extracted until recently or from other sources. Extracting more than the annual recharge means that you are tapping into this water, and once this water also gets depleted, the area runs out of water.
When this happens, it is called Day Zero. Many cities around the world are on the verge of this point. Cape Town was recently in the news for this. Other cities that frequently make this list are Sao Paulo, Jakarta, Beijing, Cairo, Istanbul, and our very own cities – Bengaluru and Chennai.
What does India’s Groundwater extraction situation look like?
A cursory glance at the groundwater situation across states seems to suggest that India is doing reasonably well. Except for the farming belt of Haryana, Punjab, arid Rajasthan and Delhi, rest of the country seems to be either safe or semi-critical. Uttar Pradesh, Karnataka and Tamil Nadu are the other major states that need to keep an eye on their water usage, but they are still marked as semi-critical
However, in terms of population, states that are in the red constitute 10% of India’s population – 12.2 crores as per the 2011 census. Add states that are yellow, and this swells to 45.46 Cr people – 37.5% of India’s population.
In terms of usage, across states, the primary purpose of groundwater is for farming, followed at a distance by domestic consumption. Even in states where industries show up on the chart, they are dwarfed by domestic consumption.
Groundwater situation in Karnataka
While the states level map suggests that Karnataka is using less than 90% of its extractable groundwater, the situation across districts is a lot more varied. This is expected as Karnataka straddles different climatic region. From the coasts and the Western ghats which receive a lot of rainfall, to the arid districts of North Karnataka and the semi-arid but heavily populated districts of Southern Karnataka the rainfall and usage patterns see a lot of variation.
As can be seen in the map above, Bengaluru Urban, Bengaluru Rural, Kolar, Chitradurga and Chamarajanagara are classified as over-exploited, while Davanagere, Ramanagara and Tumkur are classified as Critical. Most of the districts that don’t form part of the Western ghats are seen to be in the semi-critical stage of extraction. In the case of Bengaluru Urban, all the 6 Taluks are categorised as over-exploited.
The main consumer of groundwater in Karnataka is the agriculture sector. The usage is particularly high in the southern parts of the state. Groundwater is heavily relied upon for domestic usage in the arid Northern districts. Industrial use is seen mainly in Bengaluru Urban and Rural districts, even exceeding the domestic consumption in Bengaluru Urban.
Groundwater situation in Tamil Nadu
While Tamil Nadu is also categorised as Semi-critical at the state level, the situation at district levels tells a more nuanced story. Out of the 37 districts in the state, nine, including Chennai, are over-exploited and four are critical. Among the 13 districts that are considered semi-critical, seven are using more than 80% of their extractable amount, and could move into the critical category in the near future.
The sectoral breakup again points the fingers at agriculture, except in the case of Chennai which is almost entirely urban.
Across India, as well as at the state levels, what can be seen is that agriculture is the primary consumer of groundwater. This is probably the price we are paying for the Green Revolution where we prioritized crops like wheat and rice over existing crops like millets. Add to this the burden of growing water-intensive crops like sugarcane, especially in areas like southern Karnataka, Tamil Nadu, Uttar Pradesh and Maharashtra, and the picture looks even more grim.
Changes need to begin with how we are consuming food, and with incentivising drought resistant crops like millets. Using treated water can also go some way in reducing agriculture’s dependency on groundwater. Unless we take strong measures soon, more of our cities will be looking at Day Zeroes.