The Puthukkadu check dam across the Noyyal river near Coimbatore could face damage during the next spell of heavy rainfall after river rejuvenation work caused severe erosion along its banks, environmentalists have warned. Water Resources Department officials have inspected the site and said steps are being taken to stabilise the retaining wall and address the erosion.
A video documenting the condition of the site showed severely eroded riverbanks and trees at risk of collapsing into the river. Environmentalists said the erosion followed desilting and river rejuvenation work carried out near the Puthukkadu check dam. Similar concerns have also been reported at the Kurichi check dam, where comparable work was undertaken by a non-governmental organisation.
R Manikandan, founder of Kovai Kulangal Padhukaappu Amaippu, said excessive and unscientific excavation had been carried out on the riverbed. According to him, steep bunds were formed on both sides of the river without adequate consideration of river-flow dynamics, while deep excavation was undertaken without technical planning for hydraulic slopes and surface drainage.
Manikandan said runoff and drainage from areas outside the bunds had not been provided with adequate outlets. He said concentrated flows had compromised the stability of the adjoining soil, creating a risk to the retaining and wing walls of the check dam. He also warned that the trees along the bunds, some of which are more than five decades old, could be affected by the erosion.
He said the condition of the Kurichi check dam banks was relatively better and might withstand the monsoon, but the intensity of erosion at Puthukkadu meant the structure could not withstand further heavy rain. The concerns were raised with the district administration, following which officials from the Water Resources Department inspected the Puthukkadu site.
A senior Water Resources Department official said desilting had taken place too close to the anicut, within a distance of 5 to 10 metres. The official said this was technically incorrect and that a gap of at least 50 metres should have been left near the structure. The department is taking steps to rectify the erosion and stabilise the retaining wall, according to the official.
The episode places attention on the technical oversight required when river rejuvenation and desilting works are carried out around hydraulic structures. At Puthukkadu and Kurichi, the immediate concern is the condition of the riverbanks, the retaining structures and the trees along the bunds as the area prepares for further heavy rainfall. The Water Resources Department’s stated next step is to carry out corrective work at Puthukkadu and strengthen the affected retaining wall.
