Dams

DAMS

A dam is an obstruction that stops the flow of an estuary or a stream. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aquaculture and maritime transport.

1. Embankment in the Sangam period

The following lyrics by Tholkappiar of the 5th Century BC make it clear that ancient Tamilians used a stone structure to store and control the waster coming from the river for irrigation.

Proof: Tholkappium, Porul 65

As a dam holds back rushing water; so a warrior becomes proud by being the first to resolutely advance and hold back a rapidly advancing army. The 'Stone Prison' referred to is an embankment.

2. Stone Dam of Karikalan

Kallanai is the oldest of the dams built in Tamil Nadu during the Sangam period and considered to be the greatest technical achievement and has been in use for more than 2100 years.

Building the Banks of the Cauvery

According to the 7th Century AD, Iranadu Chola named Punniyakumaran built the banks of Cauvery. This is mentioned in the copper plate.

Proof: Cholas – Neelakanda Sastri – Book-1, P.49

It is understood from the following evidence that the people of Sri Lanka were taken captives by a Chola King and to take revenge, Kayavagu who ruled Sri Lanka in the 2nd Century AD, invaded Tamil Nadu and imprisoned the Tamils.

Proof: Sir Lankan Book

These two messages mentioned above are dated AD 2nd and 7th Centuries ago confirm that Karikal Chola built the banks of the Cauvery.

Kallanai is Stone Prison

Karikalan did not build a dam across the Cauvery. He built a stone structure for the Cauvery to divert the water and was referred to as dam or stone prison by Sangam people.

King Karikalan, who wanted to prevent frequent breaches in the lower reaches of the Cauvery and the loss of water to the agricultural lands, built a structure made of huge rocks at the lower end of Thiruvarangaththeevu and strengthened the banks of the Cauvery to permanently stop the breach. This was a great achievement in those days. The technology used for it is more than that.

Proof: In 1853, an English engineer named Baird Sumith made a mention of Kallanai in the book 'Irrigation of Southern India' as a great engineering feat.

Technology of Kallanai

According to the research study, Kallanai is made up of huge rocks stacked one on top of the other and there was only a layer of clay between the rocks. Huge boulders were placed in the unfathomable sandy river bed. As the sand beneath the rock was eroded away by the river water, the rock slowly descended into the sand. They were covered with clay and large rocks were again placed on the rocks. So the underlying rocks were buried deeper. Then again clay was applied and rocks were placed. Again the pressure and load further buried the underlying rocks. As the rocks below were buried, the rocks were deposited on top. Eventually, when the rocks below reached the hard surface, the submergence of rock stopped. According to the research study, a huge dam called Kallanai was formed by the large rocks placed on top of each other and the clay coating between them.

Evidence

1. In 1874, 'Sir Arthur Corron' built a dam called Thauleeswaram across the Godavari based on this stone technolgy.

2. 'Sir Arthur Cotton' in his book written in 1874 mentions that many irrigation engineering constructions such as river bridges and dams were easy to complete because of the techniques learnt from the Tamils on laying foundations.