As the debate over the Zone of Influence (ZoI) around the Pallikaranai marshland intensifies, Care Earth co-founder and wetland ecologist Jayashree Vencatesan, in an interview with TNIE’s SV Krishna Chaitanya, clarified that the Integrated Management Plan never recommended a blanket one-kilometre buffer around the Ramsar site.
Instead, she argues that the report called for a scientifically delineated Zone of Influence based on hydrology, drainage, biodiversity and land-use characteristics.
There is a perception that Care Earth recommended a uniform one-kilometre Zone of Influence around Pallikaranai. Did your report actually say that?
Absolutely not. Nowhere in the report have we recommended a uniform one-kilometre Zone of Influence. The Integrated Management Plan followed the standard template prescribed by the Ministry of Environment, Forest and Climate Change, which requires every wetland management plan to identify a Zone of Influence. But the template itself never prescribes a fixed distance.
Our recommendation was that the Zone of Influence should be delineated only after detailed field verification, considering hydrology, drainage networks, biodiversity, land use and ecological characteristics. A blanket one-kilometre boundary is neither scientifically correct nor practically possible.
Then what exactly was the report recommending?
The Zone of Influence is not a distance. It is an ecological concept. The report clearly says it should be determined using hydrological and ecological attributes. We used wetland boundaries, drainage networks, settlements, satellite imagery and land-use patterns to understand how different parts of the surrounding landscape influence the marsh. The report analysed multiple 250-metre buffer intervals and directional models only as scientific tools. Those analytical buffers should never be mistaken for regulatory boundaries.
Why is hydrology so central to the report?
The entire ecological character of the marsh depends on how freshwater, stormwater and saline water move through the landscape. If those connections are disrupted, the marsh ceases to function as a marsh. People often focus only on protecting land, but wetlands are defined by water. If the drainage channels are blocked, if floodplains are reclaimed or if groundwater recharge is compromised, simply drawing a line around the marsh will not save it.
Why does the Zone of Influence become important then?
Because the marsh does not function in isolation. Activities outside the legal wetland boundary directly affect what happens inside. If construction blocks drainage channels or alters topography, water cannot reach the marsh. If groundwater extraction increases around it, freshwater inflows reduce. The report therefore recommends identifying those areas that influence the marsh’s hydrology rather than imposing a fixed distance everywhere.
Your report repeatedly refers to hydrological connectivity. What happens if that is lost?
The consequences are enormous. Pallikaranai is not merely a bird habitat; it is South Chennai’s floodplain and groundwater recharge system. The report estimates that the marsh has already lost around 70% of its water retention capacity because of shrinking wetland area and construction. Around 9 million cubic metres of water storage space has effectively been lost, which means floodwaters now spill into surrounding neighbourhoods such as Velachery, Pallikaranai and Narayanapuram.
Hydrology also maintains biodiversity. The seasonal mixing of freshwater and saline water supports hundreds of plant and animal species. Once you interrupt that balance, the ecological integrity of the marsh begins to collapse.
The report also documents significant ecological degradation over the years.
Yes. We have been studying Pallikaranai continuously since 2001, while our historical datasets go back to 1904. The marsh has shrunk by almost 90% over the past century because of urbanisation, infrastructure, land reclamation and fragmentation. What was once an interconnected floodplain is now interrupted by roads, buildings and other structures. The report records 381 species of flora and fauna, including 165 bird species, 50 fish species, 21 reptiles and 10 amphibians. Its ecological productivity is sustained because hydrology still functions, albeit under severe stress.
Some landowners fear conservation means a blanket ban on development.
Restoration is not about freezing development. Pallikaranai is surrounded by dense urbanisation and we have to work within that reality. The Ramsar Convention itself speaks about the principle of “wise use”. Compatible development is possible, but it has to respect ecological limits. We cannot continue altering drainage, reclaiming floodplains or increasing edge effects through indiscriminate infrastructure.
Do you believe your report has been misunderstood?
Yes. I don’t think the report has been read in its entirety. It is a scientific management plan. Our role was to identify ecological processes and recommend management actions. Translating those recommendations into regulations is the government’s responsibility.
Unfortunately, the current debate has focused on a single number instead of the report’s central message that conserving Pallikaranai ultimately means conserving its hydrology. Without restoring water movement and ecological connectivity, no buffer distance, whether one kilometre or otherwise, can protect the marsh.
