The Grand Anaicut, or Kallanai, is one of the world’s oldest functioning dams, constructed by King Karikala Chola of the Chola dynasty around the 2nd century BCE. Located approximately 15 kilometers from Tiruchirappalli city in Tamil Nadu, this dam was built across the Cauvery River with the primary purpose of irrigation and flood control, helping transform the Cauvery delta region into fertile agricultural land. The strategic location chosen by the great Chola King Karikala Chola and his ingenuity and foresight is a example of his keen interest in agriculture and irrigation. His earliest engineering project brought a vast track of land in the cauvery delta region under cultivation.
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| 2000 year old Grand Anaicut, Tamil nadu, youtube.org |
Above image: During colonial period dmilitary Civil engineer Captain Caldwell (1804), raised the crest of the dam by 0.69 meter and also the river embankments so that flood waters won't breach the left bank and and rush down north into the Kollidam, thus allowing surplus water into the Cauvery that cuts through the delta...
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| Location map, Tamil naduicid-ciid.org |
Measuring 329 meters (1079 feet) in length, 20 meters (66 feet) in width, and 5.4 meters (18 feet) in height, the dam was constructed using uncut granite stones—an impressive feat given the era’s limited technological advancements. The structure not only retains water in the Cauvery but also diverts surplus into the Coleroon River, aided by the Ullar River channel.
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| 2000 year old masonry dam, near Tiruchi, TN .indiancontents.com |
The Cauvery River splits upstream of Kallanai, forming the Srirangam island between the two branches, the Kollidam (Coleroon) and Cauvery, which reunite downstream. This strategic site selection demonstrates Karikala Chola's advanced understanding of hydraulic engineering.
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