CHENNAI: Everyone knows that groynes cause down-drift erosion. There is nothing new about it. If you have a disease and doctor prescribes you allopathic medicine, which has certain side effects, will you stop taking medicine? Similarly, in the case of groynes, down-drift erosion is a side effect and it has to be dealt with. We have four decades of experience in the field and did a lot of research. There is something called ‘transitional groynes’, which reduces the impact of groynes on down-drift coastlines.
We have executed several successful projects and know what we are doing. In Kerala alone, around 40 projects are being carried out. In Tamil Nadu, groyne fields in Nagercoil and North Chennai are some of the success stories. In Simon Nagar near Nagercoil, groynes built in 2003, before the tsunami, are still intact.
We don’t randomly propose groyne fields. Lot of meticulous planning and site-specific studies are carried out before making a recommendation, which many people don’t understand. It is not just that groynes only shift erosion from one spot to another.
We have also prepared a preliminary draft report for Tamil Nadu shoreline management, which gives a conceptual design for State government on how to tackle the problem of sea erosion. The report has already been submitted to the Department of Environment and is awaiting approval.
We have visited the entire coastal line, compared the present status with historical data using satellite imagery and classified the vulnerable areas. Now, the State government has to initiate steps to carry out a detailed study, wherein each site-specific study can be conducted before deciding on the erosion control measures.
Groynes must be built under technical supervision. The spacing between them is very important, which otherwise would cause harmful effects. Now because of the groynes in Puducherry, the National Green Tribunal has stalled all projects. We had proposed 10 groynes from Ennore to Ernavoor Kuppam, where 1.5 lakh people face the threat of displacement. Even that project has been stalled.
What is a Groyne?
A barrier that extends from a beach into the sea to check erosion and drifting
Transitional Groyne FieldHas normal length and spacing, which is gradually reduced to decrease the impact ofdown-drift erosion
(As told to SV Krishna Chaitanya)
(Prof V Sundar, Dept of Ocean Engineering in IIT-M, advises the Fisheries Dept in building groynes at Kovalam)