Why Tamil Nadu Needs To Augment Water Storage In The Cauvery Delta

On 24 August, Tamil Nadu Chief Minister Edappadi K Palaniswami (EPS), soon after inspecting the damaged Mukkombu (upper Anaicut) barrage, announced that the state will soon construct a regulator dam across the Kollidam river at an estimated cost of Rs 325 crore. The barrage has been damaged to such an extent that over 10,000 cusecs of water is flowing out when it should have been saved.

Tamil Nadu is currently witnessing a situation where the Cauvery river is overflowing for the first time in, probably, 13 years. According to Central Water Commission data, the water level in the state’s six major reservoirs are at a 10-year high with the storage being 80 per cent higher than normal.

The Mettur or Stanley and Lower Bhavani reservoirs are filled to capacity, while the level in other dams is higher than 90 per cent. The dams have filled up, thanks to a bountiful southwest monsoon that has given Kerala and Karnataka excess rainfall. The monsoon that began on 29 May has resulted in Kerala getting 60 per cent excess rainfall than normal, while south Karnataka has received 12 per cent excess showers. The problem for Kerala and parts of Karnataka has been that on certain days some of the regions have nearly got 100 mm of rainfall.

This has resulted in at least 1,70,000 cusecs of water being released in the Cauvery this year. Farmers in Tamil Nadu aren’t, however, happy. Farmers in Cuddalore and Nagapattinam districts have complained that they haven’t got enough water to irrigate their fields and most of the water is getting drained into the Bay of Bengal from Kollidam.

Dravida Munnetra Kazhagam (DMK) member of Tamil Nadu Assembly from Mannagudi in Thanjavur, T R B Rajaa tweeted two weeks ago that many parts in the Cauvery Delta had not received water for irrigation, leading to protests by farmers. Earlier, he had issued a statement criticising the EPS government for not ensuring that all canals in the delta received water. His charge was that many canals were not dredged properly despite the government making allocations for it in the budgets.

The 2015 Record Rainfall And After

Be that as it may. What is currently being hotly debated in Tamil Nadu is, should the state have more reservoirs or ways to preserve water in the Cauvery Delta. The reservoirs are not only seen saving water during years when monsoon showers are in excess but also during other times when a significant amount of water is allowed to go waste. For example, in 2015, Tamil Nadu received a record rainfall with at least eight districts facing the fury of floods. But over the next 12 months, the groundwater level actually declined - an indicator of how precious water is let to go down the drain.

The issue has gained significance especially after the delta faced water shortage in the last two years and Tamil Nadu locking horns with Karnataka on sharing Cauvery water. A research paper titled, “Overview of Water Management Practices in Tamil Nadu Cauvery Delta System” by S S Rajagopal of State Water Resources Management Agency, Chennai, and D Panneerselvam, Executive Engineer with Water Resources Department, said that with demand for fresh water rising in Tamil Nadu, 53 per cent of it is met through groundwater.

By getting water from the Cauvery river, including through canals, Karnataka’s irrigated area in the delta has increased from 2 lakh hectares in the 1960s to 14 lakh hectares now. At the same time, the area irrigated by the river, including through canals in Tamil Nadu has declined from around 9 lakh hectares to around 7.5-8 lakh hectares now. The misfortune for Tamil Nadu is that the land under tank irrigation, which was 9.5 lakh hectares in the 1960s, has declined to around 4 lakh hectares now.

A Case For Mekedatu?

Pointing out at these statistics, K Sivasubramaniyan, associate professor, Madras Institute of Development Studies, told Swarajya that augmentation of water is better in Karnataka. “Probably, building a dam in Mekedatu will make sense,” he said. Karnataka and Tamil Nadu have been at loggerheads over the former’s plans to construct a dam at Mekedatu. On 9 August, Karnataka Chief Minister H D Kumaraswamy told the media that he would meet representatives and farmers of Tamil Nadu for constructing a multi-purpose project at Mekedatu. The project will serve drinking water and power needs. Karnataka will construct a balancing reservoir across Cauvery. Karnataka Water Resources Minister D K Shivakumar had also met Union Water Resources Minister Nitin Gadkari seeking the Centre’s approval for the project.

Karnataka plans to construct a reservoir that can store 65 TMC (thousand million cubic) feet of water at Mekedatu at a cost of Rs 5,912 crore at Ramanagaram, 90 km from Bengaluru. The dam will help the state generate 400 MW of power and meet the drinking water needs of Bengaluru, which is facing a shortage. Tamil Nadu, on the other hand, opposes the project fearing that it might be deprived of its rightful share of water from the Cauvery river. Already, its share has been pruned to 177.25 TMC by the Supreme Court in its 15 February ruling.

Sivasubramaniyan, a native of Musiri in Tiruchi on the banks of Cauvery, said that Tamil Nadu could consider constructing a reservoir at Rasimanal, near Hogenakkal. On 24 August, the Pattali Makkal Katchi staged a protest in Krishnagiri demanding construction of a dam at Rasimanal to store water and save it from being drained into the sea. Irrigation experts say that Tamil Nadu ought to examine ways and means to store excess rainfall and water, especially during the bounty season.

Solution Lies In Check Dams

Sivasubramaniyan says that the Cauvery flows 420 km from Mettur to the Bay of Bengal and Tamil Nadu could, at least, consider constructing a check dam every 10 km upto Thanjavur. “Such a move can help to construct at least 25-30 check dams. These check dams should not exceed 5 feet in height,” he said. This is similar to what the Andhra Pradesh overnment has done on Palar river. The Chandrababu Naidu government has constructed at least 10 check dams, one every 2 km, between Nagari and Sanakuppam, the entry point for the river at Tiruvallur district in Tamil Nadu.

“Not just irrigation needs, these check dams can meet drinking water needs of hundreds of villages on the way. Currently, drinking water is available from the river within a 2 km range from its banks. Seepage helps villages between 2 km and 4 km from the banks, but villages beyond 4 km are deprived of water,” said Sivasubramaniyan. These check dams can help reach water to these villages in far flung areas.

Tamil Nadu now depends more on tapping underground water to meets the needs of potable water. This is a far cry from two decades ago when wells met the needs. In districts like Thanjavur, Pudukottai and Madurai, water is being tapped from the underground in the Cauvery delta and sourced to homes. “The underwater source in the Cauvery delta is huge,” says an expert.

The check dams can also be opened when the Mettur dam is opened for irrigation on 12 June every year. The water can help recharge underground water and allow slow flow for this purpose. This will improve irrigation efficiency of pump sets, which is only 60-70 per cent compared with 90 per cent of drip irrigation and 85 per cent sprinkler irrigation.

“Tamil Nadu should also consider constructing small channels or canals of 10-15 km length to reach dry areas. The canals, which will receive water diverted from the delta, can help cultivate at least one crop a year,” Sivasubramaniyan said.

There are other theories floating around on water sharing between Karnataka and Tamil Nadu like giving the former the priority to irrigate in case of a deficit monsoon and then the latter if a similar situation arises the following year or the next time. More importantly, experts say, prediction of the weather by the India Meteorological Department has to improve by alerting the system months ahead.

Allocations Gone Down The Drain?

On Tamil Nadu’s part, irrigation experts say that the downstream canals have to to be dredged and kept clean. The complaint against the EPS government now, mainly by the opposition parties led by the DMK, is that branch canals and sub-canals are not being maintained properly. “These canals have to be dredged regularly, at least once in two years,” said Sivasubramaniyan.

Rajaa has, on the other hand, questioned on what has happened to the allocations the Tamil Nadu government made for dredging and desilting in the state budget. In the budgets for the last and current fiscals, the state had allocated Rs 300 crore each to carry out dredging and desilting to help rejuvenate water bodies. DMK working president M K Stalin has wondered why the irrigation department hasn’t had any long-term vision. Stating that he is pained to see huge amounts of water being drained into the sea, he tweeted asking what has happened to all the money allocated in the budget and borrowed from multi-lateral agencies like the World Bank for storing water.

Stalin has a point, but the problem for Tamil Nadu is that only a few reservoir projects have come up in the state since 1967 when the DMK was voted to power!