Sea walls and groynes – stone or concrete outcrops built from the shore into the sea to prevent erosion and drift – are touted as the solutions to beach erosion in Kerala. Yet lessons from other coastal systems suggest that they need to be treated with caution.
“Hard structures that alter the coastline drastically should be the last resort,” says Ramesh Ramachandran, Director of the National Centre for Sustainable Coastal Management.
Coastal constructions affect a process called longshore drift, the movement of sand along the coast. Sea walls, especially groynes, while preventing beach erosion in the area where it is located, cause accretion (accumulation of sand) on one side and erosion on the other. Seawalls along the east coast have resulted in loss of livelihood for fishers because they no longer have beaches to launch their boats from. The trend is catching up in Kerala as well.
“Traditional fishing methods such as the use of kamba vala (shore seines) are no longer practised here because there is no beach to haul the net onto,” says Melbin Andrady, a fisher and resident at Azheekkal, Kollam.
Sea walls are also high on maintenance. At Saikkad, a coastal hamlet in Kollam, they have fallen into disrepair, says fisherman Sundaresan S. “A mangrove planting project would be helpful, they do lessen the impact of waves,” he adds.
Thin beaches
“Locals do tend to think that sea walls will protect them from the sea,” says scientist K. K. Ramachandran who studies coastal processes at the National Centre for Earth Science Studies in Thiruvananthapuram. “But sea walls have created more problems than solutions. Out of the 588 kilometres of coasts in Kerala, 388 km have seawalls. Over time our beaches have become very thin, and this is also because rivers do not bring in as much silt now – we have dammed rivers. We have to provide maximum ecological flow to rivers.”
“Soft measures such as bio-shields and geotextiles should be the first line of defence,” says Ramesh Ramachandran. Bio-shields such as mangroves help prevent beach erosion and do not require maintenance.
Species like the Beach morning glory ( Ipomea pes-caprae), a creeper, can also act as bio-shield. The first to colonize sandy stretches, this species is unaffected by salt water and is known to stabilize sand dunes. Research also shows that the plant can recover well after hurricanes and tropical storms. “Spinifex grass can also control erosion to some extent,” says K.K. Ramachandran. “But we see it only on undisturbed beaches now, especially in north Malabar.”
It would be good if the Coir Board’s experiment with geotextiles (coir-filled porous tubes which are being tried in Alappuzha) works, says Ramesh Ramachandran, whose institute will soon release updated erosion and accretion maps of Kerala’s coasts. .”
