To identify the causes of the flooding issue, DT Next visited the streets and roads of divisions 131 and 138, in which KK Nagar falls. During the visit, it came to light that despite being a sloped surface, the stormwater drains under the Adyar bridge near Kasi Theatre (division 138) could not take rainwater to the river. Rainwater mixed with sewage gets overflowed on either side of the bridge.
Poor interlinking of drains under Adyar bridge near Kasi Theater results in an overflow of rainwater.
This clog, at the fag end of the stormwater drain network of the locality, is the main reason for the flooding of several areas in 131 and 138 divisions. This creates a domino effect, affecting the areas in all of divisions 131 and 138.
Another reason for the flooding is the unnecessary detouring of stormwater drains in several parts of the locality. For instance, the Greater Chennai Corporation has linked a stormwater drain of PT Rajan Road to Ashok Pillar Road stormwater drain. This drain carries the water from PT Rajan Road via Ashok Pillar Road, Jawaharlal Nehru Road, and to Adyar River. Instead of making this detour, the engineers could have linked the PT Rajan Road drain with the Anna Main Road drain by providing a culvert. This culvert could have drained rainwater into MGR Canal, which is only a few feet away. By doing this, the civic body could have saved Ramasamy Road, Rajamannar Road, and other streets from flooding.
A temple encroaching upon a stormwater drain near KK Nagar bus depot.
Apart from these intangible issues, one palpable issue is encroachments on the stormwater drains making desilting impossible at several points. During the visits, three temples were seen built over the drains, covering even the manholes.
Reverse gradient and flaws in design
Dayanand Krishnan, a GIS expert, who extensively studied the stormwater drain maps of KK Nagar, pointed out errors in the maps. "In the map of division 131, the flow of water has been marked from PT Rajan Road to Ashok Pillar Road (meaning water flow from division 131 to 138). However, in the map of ward 138, the water flow has been marked from Ashok Pillar Road to PT Rajan Road (division 138 to division 131)," he pointed out.
Explaining the flaws in the design, Dayanand Krishnan said there is a reverse gradient near the Adyar River. This blocks the water from entering the river, resulting in the flooding of other areas.
"Also, there are several roundabouts that could have been avoided. The mean sea level of the locality is nine metres while Adyar River's mean sea level is three metres. There is a natural slope of 20 feet. If the gradients of the drains are built accordingly, there would have been a free flow of water," he explained.
When contacted, a Chennai Corporation engineer said measures have been taken to remove floodwater. "During the previous years, water stagnation in Rajamannar Road used to continue for more than five days. Now, we are clearing the water within two days," he added.
Responding to a query about frequent flooding in KK Nagar despite the presence of the MGR Canal, the engineer said the canal originates from 131 division and water from Valasaravakkam, Porur, Ashok Nagar and other areas drain into the canal. "Due to this, inundation occurs in KK Nagar. MGR Canal has been desilted and water flows freely," he said.
Drain status in division 131
Number of streets - 133
Streets with stormwater drain - below 50
Drain status in division 138
Number of streets - 199
Streets with stormwater drain - below 30
This spot near KK Nagar bus depot has a temple encroaching the stormwater drain. But instead of clearing the encroachment, the Corporation has conveniently stopped showing the stormwater drain passing through this area on its map. There are manholes near to the area and water, though in small amounts, passes underneath temple premises
Udayam Theatre Junction is a perennial waterlogging area as the water from ward 131 flows to this area. And since it lacks the capacity to handle the situation, whenever there is a decent rain Kamarajar Salai, Rajamannar Road, Ramaswamy Road and RK Shanmugham Road in division 131 get flooded
From this area under Kasi Theatre Bridge to the Adyar river, there is a natural slope of 20 feet. However, the engineering flaws in the construction of the stormwater drain has resulted in the water taking a reverse gradient and causing waterlogging in division 131
It's here on Ashok Pillar Road that the stormwater drain starts. Instead of the drain taking a short diversion to the right and connecting to the MGR canal which flows into the Adyar river, it is taking a roundabout way to the left via Jawaharlal Nehru Road, encountering several bottlenecks
Here on Ramasamy Road, there was a building encroaching the canal. Even after the building was demolished, the civic body failed to remove the basement portion of the building that continues to block stormwater sewer from draining into the MGR Canal
Chennai's storm water drain network extends to just 2,058 km though it has 33,374 interior roads stretching over 5,525 km and 471 bus route roads extending to over 387 km. 1,000 km stretch of stormwater drains in the city came up in the past five years.
Even if the to-be-constructed Kosasthalaiyar basin project is added, the entire drains network in the Greater Chennai Corporation limits will come to only 2,500 km which is less than half of its road network.
Of the 15 lakh houses in the city, only eight lakh have sewage connections. The rest of the city households are letting sewage into storm water drains. The GCC does not have a drain network map, but only measurements of a drain along a particular street.
Official apathy, encroachments and muddied waters
V Gopalakrishnan, an activist based in KK Nagar alleged that the Chennai Corporation has been encouraging encroachments in the area. "There is already a stormwater drain in Ramasamy Road, but shops have encroached the drain. Instead of removing the encroachments, the civic body has built another drain adjacent to the old drain," he said.
He also pointed out that a temple is encroaching upon a drain near KK Nagar bus depot. Even though the MGR Canal abuts the bus stand, the flow of water from the drain near the bus stand is affected due to the lack of desilting.
"On Ramasamy Road, there was a building encroaching the canal. Even after the building was demolished, the civic body failed to remove the basement portion of the building that continues to block stormwater sewer from draining into MGR Canal," he said.
Vijayakannan, a resident of Rajamannar Road lamented that the flooding problem continues for over 40 years in the locality. "Authorities are taking measures to solve the issue but the problem persists. They should identify the shortcomings and find a permanent solution," he urged.
Kumar, an autorickshaw driver and a resident, riled that water stagnation occurs whenever it rains. "Politicians and officials should take action to resolve. We complained to the MLA and water was pumped out yesterday (Thursday). But the area is again flooded after it rained today (Friday) morning," he added.
The civic body failed to provide a proper link between a stormwater drain in Rajamannar Road and RK Shanmugam Road. This is one of the major reasons for flooding in Rajamannar Road. Also, a natural pond along the road was encroached upon by a Metro Water office. "When the pond was there, Rajamannar Road did not face severe flooding issues. Also, wherever the civic body could not desilt due to encroachments, those spots are mentioned as reverse gradient spots in the maps," Gopalakrishnan said.
There is already a stormwater drain in Ramasamy Road, but shops have encroached the drain. Instead of removing the encroachments, the civic body has built another drain adjacent to the old drain -- V Gopalakrishnan, activist
Politicians and officials should take action to resolve. We complained to the MLA and water was pumped out yesterday (Thursday). But the area is again flooded after it rained today (Friday) morning -- Kumar, auto driver & resident
This flooding problem continues for over 40 years in the locality. "Authorities are taking measures to solve the issue but the problem persists. They should identify the shortcomings and find a permanent solution -- Vijayakannan, resident of Rajamannar Road