Brick structure found in Kollidam riverbed traced to Sangam period, was used for water management: T.N. Archaeology Dept.

A detailed study by the Tamil Nadu State Department of Archaeology (TNSDA) has concluded that the brick structure exposed recently on the bed of the Kollidam river at Koogur near Lalgudi in Tiruchi district, close to the ancient Kallanai dam, is a Sangam-period water regulation structure.

A team of experts from TNSDA, comprising V.P. Yathees Kumar, Joint Director; K. Rajan, Academic Adviser; Prabhakaran, Assistant Director; and Vasanthkumar, Archaeological Officer, conducted the study on August 22 and 23, 2026.

Mr. Kumar told The Hindu that the structure became partly exposed after the water level in the Kollidam receded last month. The team used sonar to identify any submerged extensions or other structural remains. Trained divers examined the underwater portions to document the dimensions and construction technique of the brick structure.

According to the study, the structure, located about 100 metres from the northern bank of the Kollidam, comprises two sections. The first section runs west to east for about six metres before curving northwards for 8.3 metres. It is about 1.75 metres wide and 1.04 metres high, with 13 courses of bricks visible. Its northern portion remains largely buried under sand.

The second section, about 11 metres from the first, is parallel to the first section. It is about 2.15 metres wide, runs east to west for 6.5 metres and then curves northwards for about 4.5 metres. Six courses of bricks are visible in its western portion and three in the eastern portion. The eastern side of the riverbed is slightly higher than the western side, the study said.

A view of the brick structure exposed recently on the bed of the Kollidam river at Koogur near Lalgudi in Tiruchi district
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Special Arrangement

The bricks measure about 39 cm to 43 cm in length, 20 cm to 22 cm in width, and 6 cm to 7 cm in thickness. Their proportions are comparable with bricks found at Sangam-age sites including Arikamedu, Keeladi, Mangulam and Poompuhar, where bricks of approximately 42 x 21 x 6 cm, 38 x 22 x 6 cm, 35 x 18 x 6 cm, and 36 x 18 x 6 cm respectively have been recorded, Mr. Kumar said.

The structure’s design, dimensions, and location in the Kollidam riverbed indicate that it was built for water management during the Sangam period. Mr. Kumar said a similar water management structure were exposed during excavations conducted at Poompuhar.

A similar water management structure exposed during excavations conducted at Poompuhar
| Photo Credit:
Special Arrangement

The study has linked it to the Kurampu, a water-management structure comparable to a check dam and referred to in literary and inscriptional sources. The study notes that such brick structures were later replaced by stone anicuts and later, during the British period, by iron sluices.

Since the Kollidam lies at a lower level than the Cauvery, the study suggests that an early structure may have been built across the connecting river Ullar to regulate the flow of Cauvery water into the Kollidam. He said further explorations of the structure could only be carried out when the water level reduces.

Last month, experts from the Archaeological Survey of India, Tiruchi Circle, had also studied the exposed structure and concluded that it could possibly be a Sangam-period irrigation structure.