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Flowing waters for fertile fields

Life source: Water gushing out of the Grand Anicut in Thanjavur Photo: M. Srinath  

The Grand Anicut built by Raja Karikala Chola in the second nd century A.D. is still been a marvel in engineering.

It is a unique structure built just with large boulders brought over and sunk in the Cauvery sand, a task arising of a desperate need for irrigating fertile fields below when the floods breached the left bank and rushed down north to join back its counterpart the Coleroon, leaving its delta high and dry.

Also this was the lone solution available centuries before the reputed Punjab engineer Dr.A. N. Khosla, I.S.E. came up with an engineering design for structures to be built on permeable foundations.

Strong structure

According to data available with the Public Works Department, floods to an extent of about 5260 cumecs (1,86,000 cusecs) have been discharged through this anicut with minimum or no damage.

It is possible that higher floods could have flown over in the past when there were no other structures in the river.

The anicut is 328 metres (1,080 feet) long; 12.20 to18.30metres (40 to 60 feet) in width and 4.57 to5.49 metres (15 to18 feet) in height.

The main function of this anicut was to retain the supply in the Cauvery and its branches and pass on the surplus into Coleroon through the Ullar river.

To save the crops

The entire work chould have been done employing local labour and utilising whatever experience they possessed at that time.

It is on record that thousands of slave labour brought from Ceylon after the Cholas' conquest were employed.

The sheer necessity to save the crops in the delta and provide water whenever needed should have driven the ruler to take up the arduous task.

Not much is known as to how delta irrigation sustained through the centuries after the Grand Anicut was built.

When the British took over Thanjavur from the Mahrattas in 1800, irrigation work was neglected but the supply realised in the Cauvery was inadequate.

In 1804, Captain Coldwell repaired the Grand Anicut and provided dam stones 0.69 metre in height on its crest and at the same time, raised the river embankment above, ensuring additional water to the Cauvery.

In 1829, Major Sim proposed undersluices in the Cauvery with outlets in to the Coleroon to prevent the accumulation of silt in the upper reaches.

The Public Works Department recently took up renovation work on the Grand Anicut with an outlay of Rs. 21 crore sanctioned by the National Bank for Agriculture and Rural Development.

Rajya Sabha member Tiruchi N. Siva drew the country’s attention to the historic Grand Anicut popularly known as Kallanai as an apt case for world heritage status. Siva hailing from Tiruchi, while making a special mention in the Rajya Sabha recently pointed out that Kallanai by virtue of it being an engineering marvel is a fit case for listing as a world heritage site.

Built by Karikala Chozhan, the Kallanai is one of the oldest water diversions or water regulating structures in the world that continues to be functional. Though a large number of tourists, engineers, and historians visit this tourist spot, the importance of the Anicut and its historical background are less known.

Mr. Siva had quoted clause (IV) of the selection criteria of the heritage site: “To be an outstanding example of a type of building, architectural or technological ensemble or landscape which illustrates a significant state in human history.”

He said the dam is seen as a model for engineers across the world.

Syed Muthahar Saqaf

Grand dam

Locally called Kallanai, the Grand Anicut dam, was made of unhewn stones.

The dam is 1080 foot long (329 meters) and 60 foot wide (20 metres) and is regarded as an engineering marvel.

Grand Anicut is believed to be the world’s oldest surviving dam.

This massive structure was later reinforced by the British.

Originally the structure was built to divert the river water through canals across the fertile delta region for irrigation.

The area irrigated by the ancient irrigation network of which the dam was the centrepiece was 69,000 acres.

By the early 20 th century, the irrigated area has been increased to about one million acres.

At present the dam caters to irrigation needs of 12 lakh acres.

The PWD a few years ago undertook modernisation work at a cost of Rs. 21 crore sanctioned by NABARD.

Syed Muthahar Saqaf

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Printable version | Oct 21, 2021 1:38:31 PM |

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