Tamil Nadu’s Cauvery delta has grown rice for millennia but environmental alarm bells warn that the days might be numbered for large-scale rice cultivation. Within a few decades, intensive farming practices have changed almost everything about the region, with potentially irreversible consequences. It has ramped up water use even as the Cauvery river dispute choked off water supplies. The delta is almost sucked dry now and its soil is stripped of nutrients. Nutritious native varieties that kept the soil and the people farming it healthy have all but disappeared.
Cauvery delta, South India’s largest delta, is crucial for Tamil Nadu’s food security. For farmers here, growing paddy is as much about a sense of duty and pride as survival. But the fight over water access has pushed farmers to extremes. The delta is fed by the Cauvery river that originates from the neighbouring Karnataka state. Soon after the Green Revolution introduced high-yielding, water-thirsty paddy varieties here in the 60s, Tamil Nadu’s Cauvery water-sharing dispute with Karnataka escalated. As the dispute peaked in the 90s and 2000s and river water supply shrank, farmers increasingly switched to borewells, using up more water, instead of less.
A four-month investigation by Navya PK shows that farmers here are staring at a future of low yields, or even one without farming. Part 1 investigates how much water farmers are drawing, and how this will affect the delta’s residents and the consumers of the rice grown here.
Most families in the Cauvery delta depend on agriculture for their livelihoods. Growing less is not an option. So when water runs out, they dig deeper to find it. The government helps by pumping the water out for them for free. But soon, no matter how deep farmers dig, the water will run out.
Nearly all delta districts now draw water at an unsafe pace, according to India’s Ground Water Board. This will permanently impact the quality and availability of water, and the stability of the land here.
Farmers are using more groundwater to grow more paddy
During the Green Revolution, the government aggressively promoted growing paddy three seasons per year—an intensive farming practice that would suggest, incorrectly, that farmers have access to unlimited inputs, including water. Later, when water supply from Cauvery river shrank due to the inter-state dispute in the 90s and 2000s, many farmers opted for fewer farming seasons per year. But soon, they dug borewells and reverted to their usual pattern of two- or three-season paddy farming. For a while, once the borewells were dug, water was free and unlimited.
Thennilavan M, 32, is one such farmer in Soorakkottai village of Thanjavur. In the 2000s, his family was forced to reduce paddy farming from two to just one season due to Cauvery water shortage. But they resumed two-season farming after digging a borewell 10 years ago.
Now Thennilavan farms the entire ‘kuruvai’ season between June and September by pumping his borewell round the clock. But his anxiety peaks this season. “After summer, water level in the borewell would already be low. If the monsoon is also poor, water level drops suddenly and I keep worrying if the crop will die, after everything I spent on it.”
In areas like Orathanadu in Thanjavur, borewells have apparently been dug to depths of 700-1,000 ft so that farmers can grow all three seasons of paddy.
Cauvery delta comprises Thanjavur, Thiruvarur, Nagapattinam and Mayiladuthurai districts, along with parts of five other districts. These districts alone grow two-fifths of Tamil Nadu’s rice. And half of this is accounted for by just Thanjavur and Thiruvarur.
In this article, we analyse seven delta districts that grow rice as their major crop—Thanjavur, Thiruvarur, Mayiladuthurai, Nagapattinam, Pudukkottai, Cuddalore and Tiruchirappalli.
Just to grow paddy, they collectively extract 1300 billion litres of groundwater a year, equivalent to draining Chennai’s Velachery lake 10,000 times.
Farmers’ groundwater use is increasing over the years as well, our analysis of data from the Central Ground Water Board (CGWB) shows. Together, these districts now extract a third more groundwater for paddy irrigation than they did a decade ago. Every delta district’s groundwater use, except Thiruvarur, increased in the past decade.
Among the districts, the biggest user is Thanjavur, taking up a third of the water.
Thiruvarur farmers use less groundwater for a few reasons. The district has a vast, unlined canal network that may be recharging the groundwater, says Prof P Chinnasamy, hydrologist and Associate Professor at IIT Bombay. And in parts of the district, groundwater is too salty for farmers to use.
In contrast, water use rose the sharpest in Nagapattinam and Mayiladuthurai districts combined, doubling over the decade. (Since Nagapattinam was bifurcated into these two districts in 2020, CGWB has reported only combined values for both.)
Prof Chinnasamy says groundwater use and farming in the delta increased as newer technologies and better pumps made water more accessible, but not more plentiful.
In all delta districts, except Thiruvarur, paddy farmers’ increased groundwater use also corresponds with an increase in the gross cropped area (total area farmed across multiple seasons in a year). This means, as the area under paddy cultivation increases, farmers are relying on more groundwater to meet the water demand.
To see the chart for all six districts, click here.
Water extraction continues despite warning signs
Farmers who eventually use up groundwater have limited choices: dig deeper and hope for the best, or get out of the business. The droughts of 2016-2017, in fact, pushed over a hundred farmers in the region to suicide.
Veeramani N, 69, a farmer and retired school headmaster in Arayapuram village, Mayiladuthurai district, uses borewells to grow paddy two seasons a year. When he started farming 25 years ago, his borewell had water at 40 ft, but now the water level is down to 150-200 ft. Asked what he would do if his borewells run out of water, Veeramani says, “Then we will also dig down to 1,000 ft, like people in Karur and Salem districts do.”
Three-quarters of the cropped paddy area in this district relies on borewells, according to an officer at the Office of the Joint Director (Agriculture), Mayiladuthurai. But this doesn’t mean farmers have enough water. “Overall, only half the farmers in the district have assured water supply. The rest are gambling.” Paradoxically, while many farmers suffer water uncertainty, a few farmers in parts of the district with sufficient groundwater extract as much as they can, to grow paddy all three seasons including in summer when no other water source is available.
Because of the relentless extraction, Mayiladuthurai now ranks fourth among Tamil Nadu’s 38 districts with the least groundwater available for future use. Thanjavur ranks among the bottom half districts. The worst off is Nagapattinam, which is excluded from CGWB’s district list altogether as all its assessed units had only salty, unusable groundwater. The past decade’s CGWB data shows these districts are ‘overexploiting’ their groundwater, which means they draw more water annually than can be replenished. Instead of stopping water extraction before crisis levels were hit, the groundwater supply is either hitting rock bottom or becoming contaminated with salt.
Whereas Thiruvarur, Tiruchirappalli and Cuddalore draw 70-90% of the extractable groundwater, which puts them in CGWB’s ‘semi-critical’ category. Of the seven districts, Pudukkottai was the only one with safe extraction levels.
Veeramani in Mayiladuthurai, and Thennilavan in Thanjavur, say that some marginal farmers in their villages have already quit farming because of water shortage. Such farmers sell or lease their land to large farmers who can afford borewells.
“I don’t know what the future holds. In the next 10 years, the water level here may go down to 500-600 ft,” says Thennilavan. “Even if we spend more, we can’t predict climate change. We see excess or low rains more often now, leading to crop loss.”
In the tail-end villages of the delta, close to the coast, Thennilavan’s nightmare is already a reality.
Tail-end villages already in distress: a portent of what’s to come
Understanding what happened in the tail-end villages, where rice is barely viable now due to water over-extraction and loose regulation of water resources, is crucial to preventing a similar fate across the region, according to our data and experts.
In the tail-end villages near the coast, that receive the last and least of Cauvery water, borewells were more popular in the 70s itself. Later, in the 2000s, nearly every farmer dug these. This, along with sand mining and industrial water extraction, has already depleted the groundwater here. With groundwater depletion, seawater has entered the aquifers.
With no control over water availability, nearly all farmers here now grow just one season of paddy a year. But even this crop may not survive the increasingly frequent floods and droughts hitting the region.
In Manikollai village, Cuddalore, farmer R Radhakrishnan lost the paddy crop in over a third of his land (14 acres) during the Fengal cyclone that hit the delta in November. Radhakrishnan, 72, says he will have to shell out Rs 10,000-15,000 per acre to prepare the land again, grow and transplant new seedlings - that is, a total of up to Rs 2 lakh. Farmers say the government’s crop insurance scheme hardly covers such losses.
In Kumaratchi, another tail-end region in Cuddalore comprising 58 villages, borewells became widespread about 20 years ago but dried up within 10 years, says Anbazhagan M, a farmer here. ”Now each village has only 1-2 borewells with water at about 600 ft depth, owned by rich farmers. Others depend on rain and the available Cauvery water.” He says he hardly makes profits from his four-acre paddy farm now, and grows cotton half the year as it needs less water.
Even clean drinking water is a challenge to find in the tail-end villages now.
Dr S Janakarajan, economist and President of the South Asia Consortium for Interdisciplinary Water Resources Studies (SaciWATERs), says the reality faced by tail-end villages hints at the future of the entire delta. “Groundwater extraction and seawater intrusion has led to 100% salinity in Nagapattinam district. Here the damage is already done. And since the delta is a coastal region, you get more floods - so it’s either flood or drought. So food security is going to be majorly threatened.”
A modeling study, published in 2023, projected a 39% increase in seawater intrusion in the delta by 2050 if groundwater is used up at the current rate.
Dr Janakarajan also warns about the subsidence or sinking of land happening in Cauvery delta due to the extraction of groundwater and hydrocarbons.
CGWB’s Regional Director, Chennai, did not respond to our question on any action they’ve taken to control water extraction in the delta.
The state government should have heavily invested in recharging groundwater and limiting farmers’ extraction here, says Dr K Ramaswamy, former member of the State Planning Commission (Agriculture and Irrigation) and former vice chancellor of Tamil Nadu Agricultural University (TNAU).
“During the summer (third) cropping season, water extraction happens in a sizable area in the delta. So the government should stop free power supply between January and June.” But parallelly, in this period, TNAU should promote pulses cultivation which needs less water, and the government should procure pulses from farmers at the MSP or arrange the logistics for sales, he says. “This can initially be done in say, 15 villages as a three-year model project.” Though the TNAU had promoted pulses cultivation long ago, many farmers didn’t adopt it due to the lack of support.
Dr Ramaswamy also suggests building groundwater recharge structures on riverbeds as well as freshwater tanks along the coast, which would improve groundwater levels and prevent it from mixing with seawater. None of this is new - these have been part of TNAU’s recommendations, individual bureaucrats’ efforts, and farmers’ associations’ demands. But these projects didn’t take hold in the absence of continued government support.
Meanwhile, delta farmers continue to demand more Cauvery river water, hoping it will solve their problems. But no solution seems to be forthcoming, especially as Karnataka plans to build one more dam upstream.
It is not just groundwater depletion and climate change that are pushing farmers to the brink of collapse. In Part 2 of this investigation we will investigate how widespread intensive farming practices meant to grow rice faster and cheaper have backfired.
(Reporting for this story was supported by the Environmental Data Journalism Academy - a programme of Internews’ Earth Journalism Network and Thibi)
View the data analysis conducted for this series, and the methodology used for the analysis.