Encroachments, irregular desilting clog Chennai’s stormwater drain network

The lack of a uniform survey of encroachments along canals and stormwater drains (SWDs) across Greater Chennai Corporation (GCC) zones, coupled with irregular desilting, is exacerbating water blockage issues in the city, officials and experts say.

Several key zones, including Tiruvottiyur, Tondiarpet, Thiru-Vi-Ka Nagar, Ambattur, Anna Nagar, Teynampet, Kodambakkam, and Perungudi, have not conducted simultaneous surveys to enumerate encroachments along major water channels.

In Thiru-Vi-Ka Nagar, authorities have identified 118 encroachments along Gandhi Canal in Taramani. “This is an annual exercise, and eviction will take place once funds are allocated for providing alternative housing,” said an official from Zone VI. However, the Kolathur Canal, under the Water Resources Department (WRD), is still awaiting a survey.

Lack of uniform data

Senior GCC officials have admitted that there is no comprehensive data on encroachments across all wards. They have urged the Revenue and Finance (R&F) departments to ensure uniform surveys would be conducted in all 15 zones.

However, an R&F official clarified that since 2014, zonal officials have been handling encroachment cases through Assistant Revenue Officers, who escalate them to the Deputy Collector (Revenue), then to the respective Regional Deputy Commissioners, and finally to the Commissioner via the Assistant Commissioner (R&F). As a result, the R&F department does not directly oversee encroachment surveillance.

In Kodambakkam Zone, for example, no survey has begun. “In West Mambalam’s Jothi Nagar, nearly 100 illegal tenements have been built over an SWD, while over 200 encroachments persist in Sarathy Nagar,” a GCC official noted. Despite repeated notices, residents refuse to vacate. Additionally, the absence of an underground drainage system has led to sewage directly flowing into the SWDs, further straining them during monsoon.

Eviction challenges

Encroachments behind the MGR Canal are obstructing GCC’s widening efforts, which are crucial for reducing flooding in nearby areas, another official said. “Two years ago, clearing Rajamannar and Ramasamy streets helped widen SWDs,” he added.

In Tondiarpet Zone, officials are yet to verify encroachments around Captain Cotton Canal, Jawahar Canal, and Vyasarpadi Link Canal. Some zonal officials, including those in Thiru-Vi-Ka Nagar, admitted they were unaware of an annual enumeration process, stating that evictions are typically conducted in response to complaints from residents or ward committee meetings.

Additionally, while GCC maintains Otteri Nullah and Virugambakkam Canal, officials noted that the WRD must undertake a survey of illegal sewage outlets and encroachments since the land belongs to the department.

Desilting and drain maintenance

Zonal officials acknowledged that encroachments disrupt water flow but pointed out that eviction requires police support. “Illegal sewage outlets into the SWDs, due to lack of underground drainage connections, put immense pressure on the drainage system, especially during monsoon,” an official from Thiru-Vi-Ka Zone said. On being notified, the Chennai Metro Water Supply and Sewage Board has assured that steps would be taken, he added.

Encroachments on SWDs, including the construction of concrete steps and ramps, have made desilting efforts difficult. “These structures are demolished during desilting, but they reappear despite repeated warnings,” officials said.

Some engineers expressed concerns over the social impact of large-scale evictions, stating that removal affects long-time low-income residents and shopkeepers, disrupting children’s schooling and transportation. “Many argue that relocating people for a few months of flooding isn’t justifiable,” an engineer remarked.

R. Loganathan, a District Executive Committee Member of CPI (M) in North Chennai, contested the idea that encroachments were the main cause of drainage blockage. He attributed the issue primarily to the lack of regular desilting and deepening of waterbodies and SWDs. “Desilting is done hastily before heavy rains instead of being conducted year-round. This is especially evident in areas like Vysarpadi’s V.O.C. Nagar and Kannagi Nagar. The problem is worse in added zones like Perungudi and Sholinganallur,” he claimed.

Deputy Mayor M. Magesh Kumaar, however, maintained that GCC was actively clearing encroachments. “Encroachments are not the major obstruction to waterbodies and SWDs. The Corporation has the authority to clear them, and the process is being carried out regularly,” he asserted.