Yesterday, I took a boat ride with some friends up the Pondicherry coast, and beyond into Tamil Nadu. The coastal erosion is really quite horrific. As you can perhaps make out in the 2006 satellite image, above, more than 98% of the beach to the north of the harbor has completely disappeared, replaced by rip-rap seawall. Seven kilometers of beautiful white sand are gone in Pondicherry, and the environmental disaster now stretches well into Tamil Nadu.
The cause of this destruction is neither mysterious nor complicated. The beaches were originally starved of sand by the construction of the Pondicherry Harbor (completed in 1989). The predominant direction of sand migration on the Coromandel coast is from south-to-north, with a net displacement of more than a half-million cubic meters of sand annually. The harbor wall traps the sand, accreting beach to the south and eliminating it to the north, as you can clearly see in the satellite image. The accumulated sand along the harbor wall is the large white triangular area in the far right (south) of the photograph. The dark streak to its immediate left, extending into the sea, is water of the Ariyamkuppam River. The northern edge of the Union Territory of Pondicherry can be pinpointed near the left edge of the photograph: it is the spot where the dark boulders of the seawall ends and light colored eroding sand of Tamil Nadu beaches begins.
Initially, the government guardedly acknowledged its error in building the harbor by agreeing to dredge sand from the accreting side of the harbor wall to the malnourished side. This man-against-nature struggle was, perhaps, doomed from the outset; but the governments failure to follow through with the dredging didn’t help matters. Within a few years, Pondicherry’s justly famous beach, which framed the central promenade of the city, had eroded away, and Beach Road itself was threatened.
Leave it to the Government of Pondicherry, which teeters between corruption and ineptitude, to make a horrible situation apocalyptic. Rather than tearing down the harbor, and restoring the natural balance, the government embarked on an insane program of dumping boulders onto the shoreline, creating a hard barricade against the onslaught of waves and longshore currents. The only problem with seawalls: they don’t work.
Whereas sandy beaches dissipate the erosive energy of the waves as they wash landward, seawalls are the immovable object to the waves irresistible force. The crash of the waves into the seawall produces ever-greater erosive forces, directed in eddies to the unprotected coastal floor. As the tidal sediments are eroded downward, the rip-rap boulders tumble into the sea, requiring replacement with ever-more boulders. And by the way: beach elimination and seawall-driven tidal zone erosion causes the land-side water table to become saline, something that Pondicherry is now experiencing firsthand.
Not content to have made two of the most basic, well-studied errors in coastal management, the Government of Pondicherry decided to outdo even its own stunning brainlessness: it has been actively building a series of groyns along the coastline. A groyn, for those of you who do not despoil beautiful beaches for kicks or profit, is a solid wall, typically made of rock or concrete, which extends perpendicularly from the shore into the sea. The concept of the groyn, thoroughly discredited since New Jersey’s disastrous experience in the 1960s, is that by interrupting longshore drift, sand migration is stopped and all the sand stays put. Nice try. Some sand will always accrete on the windward side, but will always be eroded away from the leeward. And the disruption of the normal patterns of sand migration simply starve the beaches farther and farther up the coast.
Due to jurisdictional constraints, the government’s seawall- and groyn-building mania extends only to the Pondicherry – Tamil Nadu border; but the effects extend well into Tamil Nadu itself. The Pondicherry groyns are devastating the Tamil Nadu Beaches. The once-spectacular Quiet Beach in Thandhirayankuppam, Tamil Nadu has almost disappeared, in just a matter of months, as a consequence of the recently constructed groyns at the northern edge of the Pondicherry coast.
If all this stupidity weren’t enough, the Government of Pondicherry has an even bigger calamity in the works. It has given away 153 acres of prime property, in the area of the old harbor, to private developers to build a new deep-water port, ten times the size of the existing harbor. The environmental impact is likely to reach all the way to Chennai.
There is a simple solution to this man-made disaster: dismantle the harbor and groyns, and let the seawalls fail of their own accord. Permit the natural flow of sand to regenerate Pondicherry’s coastline. The Government of Pondicherry is not likely to be quick to own-up to its past failings. It is time for the citizens of Pondicherry to do what the people of India routinely neglect to do: demand that their elected officials act in the public interest, rather than in corrupt or politically expedient self-interest.
View a PowerPoint Presentation giving an overview of the beach errosion problem and the new port threat.
View a PowerPoint Presentation showing the erosion of Quiet Beach, north of Pondicherry, in Thandhirayankuppam, Tamil Nadu.
Watch a CNN-IBN report about the ongoing environmental disaster.
Read “Deep Waters“, the cover story in the May Issue of Down to Earth, India’s leading science and environment publication.
See original source documents, articles, and other references on the Save Our Beach blog.