Chennai: About 10cm rain spread across 36 hours is not heavy by any stretch of imagination, and yet at least 135 localities in the city suffered water-logging with residents wading through knee-deep water on Thursday.
While office-goers and businesses suffered due to strong morning-hour spells, low-lying localities like Velachery, Vyasarpadi, Kodungaiyur, and Pulianthope faced up to knee-deep inundation. As Pazhavanthangal and Aranganathan subways were inundated, access to GST Road and Anna Salai was cut off for several hours, leading to traffic snarls.
The Greater Chennai Corporation operated close to 50 motors and pumped out water at more than 100 locations, including two subways, by the evening. Some localities like AGS Colony in Velachery still had two-three feet water, despite the water resources department building retention walls at Veerangal Odai, a major flood carrier.
"If the retention wall wasn't there, we would have had five feet of water. Now, there's still up to three feet of stagnation, as water from other locations enters our area. The gradient issue with drains needs to be addressed," said Geetha Ganesh of AGS Colony. SWDs being clogged was the major reason for inundation as water did not recede.
In Anna Nagar and Pulianthope, the lack of a retention wall in Otteri Nullah led to a breach, causing inundation. GCC collected this water in their sump and pumped it out in less sensitive canal spots along the route.
These rains also cleared sewage from major waterways like Otteri Nullah, Mambalam Canal, Veerangal Odai, and Cooum and Adyar Rivers. Experts say this may replenish the groundwater along the waterways. "Our studies in the past show fresh water aquifers along Adyar River neighbourhoods, particularly near Malar Hospital. Flood plains will definitely get replenished, yet it is only a temporary relief. We need to divert sewage permanently," said Hydrogeologist J Saravanan, a resource person with Rain Centre.
Eight fallen trees were removed on Thursday. Mayor R Priya inspected the relief work from GCC's integrated control and command centre and ordered officials to fix the remaining areas by Thursday night.