CHENNAI: With issues plaguing the Velachery Lake being cited as major contributing factors to the floods that ravaged the region last December, the residents have proposed a 4D approach – ‘Deflect, Drain, Desilt and Deepen’ – for saving the waterbody. Under this initiative, sewage outfalls could be deflected with inlet sluice gates and daily sewage through interceptors to a collection well and then to the sewage treatment plant. This should be followed by desilting and deepening the lake.
In the wake of Velachery getting inundated for almost four days during the recent floods, a GIS study was initiated by the Velachery AGS Colony Residents’ Welfare Association and carried out by GIS consultant Dayanand Krishnan.
Going by the study findings, Velachery lake has shrunk from its original extent of 265 acres to 55 acres and its storage capacity plummeted from 19.24 Mcft to 4.82 Mcft. The waterbody now has the capacity to hold around 4 cm of rainfall-runoff volume against its original capacity of 15 cm. The study also highlighted that the flood surplus macro drain was choked by waste at its entry point.
In its neighbouring areas, the Ullagaram lake that originally spanned across 59 acres, has been repurposed for residential use, according to the GIS study. As a result, the flood surplus disposal channel of Veerangal Odai becomes overloaded, spilling over to the low-lying areas of Velachery and Madipakkam and flooding them.
The report also indicates that the Velachery Tambaram Road and Pallavaram 200-feet Radial Road are blocking the natural flow of water into the Pallikaranai marsh. As for the Adambakkam lake, the residents recommend an additional closed macro-drain conduit along the 100-foot road.