Built by Chola King Karikalan during the first century, Grand Anicut (“Kallanai” in the local parlance), is one of the oldest water-diversion or water regulating structures in the world.
The dam plays an important role in the irrigation system in the Cauvery delta.
Besides attracting a large number of tourists, the dam has fascinated historians and engineering experts. Though much has been said time and again about Grand Anicut, not many know the great contribution made by king Karikalan to promote irrigation in the delta region.
In this context, Chief Minister Jayalalithaa sprang a surprise recently by announcing her government’s intention to build a befitting memorial to the Chola king.
Grand Anicut is a massive structure constructed with uneven stones to a length of 329 metres and a width of 20 metres across the main stream of the river.
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 downstream when the floods breached the left bank and rushed down north to rejoin the Coleroon, leaving its delta high and dry.
The dam was meant to divert water across the fertile delta region for irrigation through canals.
The main function of this dam was to retain the supply in the Cauvery and its branches and pass on the surplus into Coleroon through the Ullar river.
The dam is seen as a model for engineers across the world. Sir Arthur Cotton’s 19th century dam across the river Coleroon (Kollidam), the major tributary of Cauvery, is stated to be a replication.
It is a sad reality that 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 into 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.
The country’s attention has been drawn to the historic Grand Anicut recently when a plea has been made in the Parliament to it in the list of World Heritage sites.