Chennai lost a third of wetlands in a decade, finds Anna University study

The study predicted that Chennai will witness fewer wet days and more dry days due to future climate scenarios.

Published: 09th March 2018 03:31 AM  |   Last Updated: 09th March 2018 02:55 PM   |  A+A-

Express News Service

CHENNAI: Chennai lost 33 per cent of wetlands during the last decade as per land use map data, according to a report submitted to the State government.The report on the study of Climate Change on Flooding in select areas of Chennai Metropolitan Area states that from 2006 to 2016, the land use maps highlighted 24 per cent reduction in agriculture land, 15 per cent increase in barren land and 13 per cent increase in settlement area.

The draft report prepared by Anna University, which was submitted to the State Planning Department, stated that during the last decade, the maximum temperature increased by 1.1 degree Celsius and minimum temperature increased by up to 0.5 degree Celsius from 1969 to 2009.The study predicted an increase in maximum and minimum temperatures in the city.

The average maximum temperature will rise 1.1-1.3 degree Celsius from 2020 to 2050 and 1.7 to 2.2 degree Celsius by 2080. Similarly, the average minimum temperature may increase by 0.6 degree Celsius to 0.9 degree Celsius from 2020 to 2050 and 1.3 degree Celsius to 1.7 degree Celsius by 2080. The study predicted that Chennai will witness fewer wet days and more dry days due to future climate scenarios.
The report focused on the flood-prone regions of Velachery and Mudichur Road, which were worst affected in the 2015 deluge.

The analysis found that of 234 nodes or junctions in these areas, 58 have been identified as flood hotspots. The areas 100 feet Road (near Velachery Lake), LIC Colony 2nd Street, Dhandeeswaram 7th Avenue East, Dhandeeswaram 7th Main Road, Southern Arm Inner Ring Road, Vijaya Nagar 7th Main Road, TNHB 3rd Main Road, Srinagar Colony Main Road, Nethaji Colony are identified as hotspots and have been found flooded during storms.

The study has suggested that storm water drains in these areas should be redesigned to cope with future flood events. Usually, the runoff from Velachery zone discharges into Pallikaranai marshland. Pallikaranai marshland receives run-off from adjoining catchment, including Velachery, Madipakkam, Perumbakkam etc. The storm water passes through the 2.8 km  Okkiyam Maduvu channel, which originates as a narrow canal from Pallikaranai marshland and drains into Buckingham Canal that flows south and enters the Kovalam estuary.The study suggested that the size of Okkiam Maduvu weir width should be increased from 120 metre to 200 metre which will reduce the flood depth in the area.

Outer Ring Road blamed for Mudichur floods

CHENNAI: The Outer Ring Road (ORR) is blamed for flooding of Mudichur, a residential hub close to Tambaram that was worst-affected during the 2015 floods, according to a study conducted by Anna Univ. The study which went into the influence of ORR on Mudichur area found that with the existence of ORR there was a 20.03 per cent increase of flooded area compared without the road. Even for moderate rain, there is heavy water stagnation on the arterial Tambaram-Mudichur Road near the junction of Maduravoyal Bypass. Stating that ORR has its influence on flood depth in Mudichur area, the study calls for the need to maintain existing drains. It also calls for adequate drains to be provided across the ORR.

Max temp went up by 1.10 C in 40 years
■ Maximum temperature in Chennai has gone up by 1.10C and minimum temperature has increased by 0.50C between 1969 and 2009
■ There has been a 13 per cent increase in settlements over the last decade

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