CHENNAI: Fishers from villages along the Kovalam sub-basin have opposed the proposed Mamallan reservoir on the Uppankazhi salt marsh, alleging that it has been designed without considering the tidal and storm dynamics of the Bay of Bengal. They warned that seawater intrusion could turn the proposed freshwater reservoir into a “salt lake”.
Speaking to reporters on Monday, the fishers said report submitted by IIT-Madras to secure exemption from the Coastal Regulation Zone (CRZ) Notification, though prepared by an ocean engineer, considers only freshwater inflows from the western catchment and treats the sea merely as an outlet for excess floodwater, without assessing tidal behaviour and storm surges.
According to a coastal inundation map prepared by the Water Resources Department, for an assumed 1.63m tidal surge and severe sea conditions, most of the marshland on which the reservoir is planned would be submerged under 3.5 to 4.5 metres of seawater.
“Every spring tide and every monsoon, we watch this land become part of the sea. The bund they are planning is not going to stop that,” said R Narayanan, a fisherman. Fishers also warned that enclosing the marsh would remove around 4,375 acres of natural flood storage, increasing the risk of seawater flooding.
A WRD official told the TNIE that the state has constituted a high-level technical committee, headed by the chief engineer (Chennai region), to examine the project. “A committee will assess the design, quality assurance measures, safety aspects and overall technical feasibility,” the official said, adding that a decision would be made based on findings and discussions with public.