Tamil Nadu

What led to the 2015 Chennai floods

 A view of the marooned Manali Express Road, Tiruvottiyur in Chennai on December 05, 2015.

A view of the marooned Manali Express Road, Tiruvottiyur in Chennai on December 05, 2015.

In its report on Schemes for Flood Control and Flood Forecasting in the country, the Comptroller and Auditor General of India (CAG) has faulted the State government on at least three counts for the Chennai floods in 2015.

In the 2017 report, the CAG has, based on the response received in December 2016 from the Water Resources Department (WRD), said there was no Emergency Action Plan (EAP) for the reservoirs in Chennai and its suburbs in case of overflow or breach. The EAP could have helped in better management of flood discharge from all reservoirs, including the Chembarambakkam tank, during the 2015 floods.

It was observed that the master plan for Chennai and its suburbs, for three rivers – Kosasthalaiyar, Cooum and Adyar – was not prepared to manage floods and for the augmentation of the water resources, based on the response received in August 2016.

The Engineer-in-Chief, WRD, stated [in August 2016] that a comprehensive master plan for Chennai and its suburbs could be evolved only in coordination with the district administration and local bodies.

The absence of coordination between the WRD, the Revenue department and the local bodies contributed to the non-preparation of a basin-wise Comprehensive Master Plan, ruling out the planned execution of macro and micro drainage networks, the CAG pointed out.

Nandambakkam flooding

The creation of a flood protection wall/embankment in the Adyar river near Nandambakkam bridge proposed [in July 2008] to the Union government under the Centrally sponsored Flood Management Programme (FMP) was withdrawn by the Chief Engineer, WRD, in March 2012.

The reason: inability of the WRD to acquire 0.69 hectares of land for the project which resulted in non-initiation of flood protection works and non-availing of Central grant of ₹7.60 crore. This could have been one of the contributing factors for heavy inundation in the Nandambakkam area during the 2015 floods, the report said.

No real-time data

No flood forecasting scheme was sanctioned for Tamil Nadu during the XI Plan under the Central Sector scheme. In the XII Plan, an action plan for the installation of 41 telemetry stations in Tamil Nadu was prepared (July 2016) but tenders remained to be finalised [July 2016].

Modernised flood forecasting infrastructure using real-time data acquisition system and forecasting models for all river basins were not developed in the State. Floods forecasting was based on the meteorological forecast and the special warning issued by the IMD, it pointed out further.

Moreover, the proposal [June 2014] to form a committee to make recommendations for enacting the Flood Plain Zoning Bill was under the consideration of the State government [August 2016].

Lack of legislation for the Flood Plain Zoning resulted in developments abutting waterways, leading to the inundation in Chennai and its suburbs during the 2015 floods, the CAG reported. However, the fact remained that the Bill on Flood Plain Zoning could not be enacted in most States even after more than 40 years since it was first envisaged, it added.

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Printable version | Jul 4, 2022 6:33:37 am | https://www.thehindu.com/news/national/tamil-nadu/what-led-to-the-2015-chennai-floods/article23326651.ece