The southwest monsoon, Tamil Nadu’s ‘other’ monsoon, is on fire this year

There is a month left before the southwest monsoon officially withdraws. But Tamil Nadu, for which this is not even the primary monsoon, is enjoying a bountiful monsoon with 90% surplus rainfall (as on September 2). While this has had a cascading effect on the State’s major reservoirs that are fast filling up, concerns about crop damage and optimum use of surplus water cannot be brushed aside.

Persistent rainfall over most districts has meant that 90 reservoirs are nearly at 88.70% of their capacity. Nearly 18 districts have registered more than 100% excess rainfall this monsoon.

August this year turned out to be a record-breaking month. Meteorologists said this was the third rainiest August in 122 years as the State received 93% more rain than its monthly average. The copious flow in the Cauvery had set a new record of water realisation from Karnataka, with the quantum crossing 200 thousand million cubic feet (tmc ft).

This year, the Mettur dam has maintained its full level of 120 feet for the past 50 days. Previously, it remained full for 78 days in 1959, 62 days in 1981, and 60 days in 1961. There is a chance this year for the dam to break its record for maintaining its full level for more than 78 days, according to officials of the Water Resources Department (WRD).

The Department of Agriculture has said the heavy rain in Karnataka and Kerala, too, has brought flows to major reservoirs this season. Agriculture Secretary C. Samayamoorthy has said nearly 80,000 acres of Kuruvai paddy has already been harvested in the Cauvery delta region. The Mettur dam was opened on May 24, 19 days before the customary date of June 12, and this helped in early harvest. The area under Kuruvai paddy has crossed 5.36 lakh acres this year in the Cauvery delta region, the highest in the last 40 years.

There have been instances of crop inundation, too. District officials have been instructed to assess the area where the yield loss is more than 33% because of crop damage. Farmers are also being advised to take precautions such as coconut harvesting, providing support to banana trees and draining the excess water from their fields, Mr. Samayamoorthy has said.

Plea for better use

However, the abundant flow in the Cauvery and the Kollidam, which have been in spate thrice since July with the flood discharge from the Mettur dam, has not directly benefited agriculture in the Cauvery delta region, say farmers.

“The heavy flood discharge from Karnataka has not benefited us but has largely drained into the sea,” regrets P.R. Pandian, president, Coordination Committee of All Farmers Associations of Tamil Nadu.

There has been a clamour for projects to augment storage. The Cauvery-Vaigai-Gundar link scheme, which envisages diversion of flood discharge in the Cauvery to the water-scarce southern districts, has taken a few baby steps in recent months.

Mr. Pandian blames lack of planning for the State’s inability to exploit the flow in the Cauvery during surplus years. Instead of citing financial constraints, the government must constitute a committee of experts to recommend measures.

Given the limited scope for creating storage infrastructure across the Cauvery and the Kollidam on the flat terrain, experts and engineers feel it is time to look at options such as lift irrigation.

“The floods in recent years have brought 100 tmc ft-200 tmc ft of water into the Mettur dam between June and August. Sixteen pumping stations must be established at six places along the Cauvery and water can be pumped through pipes on either side of the river at Mettur, Jeddarpalayam, Mayanur, Mukkombu and Kallanai. Seven barrages each across the Cauvery and the Kollidam must be built. About 50 tmc ft-60 tmc ft can be used through these measures,” says A. Veerappan, State secretary, Tamil Nadu PWD Senior Engineers Association, a forum of retired engineers of the WRD.

Farmers’ representatives have also been critical of the WRD for failing to utilise the flow in the Cauvery to fill up irrigation tanks in Tiruchi and Thanjavur districts. But WRD officials note that many of the 187 irrigation tanks under the River Conservation Division — comprising Tiruchi, Thanjavur, Karur, Ariyalur and Pudukottai districts — have storage of 50% and above.

Conserving the surplus water remains a challenge in many other districts too.

While the monsoon has brought copious water to the Bhavanisagar dam in Erode district, the excess is being discharged into the Bhavani river because the Athikadavu-Avinashi Groundwater Recharge and Drinking Water Supply Scheme, which proposes to draw water from the river and divert it to tanks in Coimbatore, Erode and Tiruppur, is yet to be completed.

Farmers in the five districts in the Madurai region, who usually are on their toes seeking water release from the Mullaperiyar reservoir every year, are glad about timely discharge in June for two consecutive years. The water discharged from the Vaigai dam, which also filled thrice over the past 15 months, is being taken up to the tail end in Ramanathapuram and Sivagangai districts. Small and marginal farmers, too, have got into action this time.

Efforts to desilt tanks and ‘Ooranis’ have fetched more inflows: Madakulam tank in Madurai and Big tank in Ramanathapuram district have water to the brim. The 58-canal scheme in Madurai district has benefited farmers in Usilampatti.

On the flip side, farmers raise concerns about surplus in dams for the second consecutive year. Last time, the rain just before paddy harvest inundated many fields. While campaigns are being conducted to insure the crops, representatives of farmers’ associations like R. Palanichamy allege that they have not got a fair compensation from the insurance companies for crop damage.

Experts have suggested that the government explore modalities of formation of minimum support price for paddy growers during such situations. Former Tamil Nadu Additional Director (Agriculture) S. Kanagaraj has said technology should be used to gauge the extent of loss accurately and compensation should be credited to the bank accounts directly.

Pointing out that other ‘kharif’ crops, including maize, millets and groundnuts, may not be affected, agriculture experts have called for measures to save the paddy, especially in the delta.

S.P. Ramanathan, head, Agro Climate Research Centre, Tamil Nadu Agricultural University, wants paddy harvest done by early September, depending on the maturity of the crops. Water release from the Mettur dam must be stopped temporarily in case of heavy rain to allow water to drain from channels and fields.

“Small dams could be built across rivers. We can prevent Kuruvai crop damage with suitable technology. River linking projects, like Cauvery-Gundar link, that will help to divert excess water to dry areas must be expedited,” he said.

The Agriculture Department and the district administration have also taken stock of the situation and initiated measures to minimise loss. Theni Collector K. V. Muralidharan said sensitisation programmes were organised for farmers before water release for irrigation. A disaster management plan has also been devised.

Notifications are being issued to enrol farmers in the crop insurance scheme under the rabi season. The State government has provided ₹2,057.25 crore as its share of the premium subsidy for the scheme.

The Agriculture Department is also confident of good samba paddy cultivation on 35.8 lakh acres in the delta, with the Mettur dam remaining full. Chief Minister M.K. Stalin has received concurrence from the Central government for advancing procurement to September. The State government has fixed a paddy procurement price of ₹2,160 a quintal for fine varieties, Mr. Samayamoorthy says.

Chennai well-placed

Healthy storage in the reservoirs in and around Chennai has kept drinking water shortage at bay this year. The storage at three major reservoirs has already crossed the 90%-mark.

WRD officials said several conservation projects — be it creating new reservoirs, improving waterbodies around the city and building storage structures across rivers — would take a few years. In the meantime, efforts are being made to reduce urban flooding.

“We are monitoring the water level and prepared to pre-empty a portion of the storage to maintain a cushion space for heavy inflow during the northeast monsoon. Most portions of the channels, being built as part of the ₹434-crore flood mitigation projects, will be functional this year,” says an official.

More to come?

September, too, could bring copious rain before the monsoon retreats, going by the India Meteorological Department’s prediction for the country. Normally, the Western Ghats districts have an edge over other parts during the southwest monsoon. But, this time, most areas in Tamil Nadu have received a good spell.

S. Balachandran, Deputy Director-General of Meteorology, Chennai, says various factors, including strong westerlies, troughs and circulations in the low level and wind instabilities, have contributed to the consistent rainfall over the State. Though most districts have recorded excess rain this southwest monsoon, it has occurred in different periods and not in a single spell.

“We cannot attribute a single monsoon or individual event to climate change. It needs an analysis of data over a larger period,” he reasons.

Weather experts have noted that the State experienced several episodes of good rain as the monsoon stayed active or even vigorous, bringing rainfall four times more than the average, something unusual for the season.

Senior meteorologist Y.E.A. Raj says there have been years in the past when the southwest monsoon performed well across the country as well as in Tamil Nadu, as in 2022. Rain deficit over Kanniyakumari, too, may be bridged. Places like Chennai have witnessed an increase in the southwest monsoon rain by 10%-15% in the past two decades. “A good southwest monsoon over Tamil Nadu may often not be well related to the upcoming northeast monsoon. Tamil Nadu has had a slightly deficit northeast monsoon during the plentiful southwest monsoon years. But there is no conclusive evidence,” he adds.

(With inputs from Deepa H. Ramakrishnan in Chennai, L. Srikrishna in Madurai, S. Ganesan in Tiruchi, M. Sabari in Salem and S.P. Saravanan in Erode.)