Thiruvananthapuram: Amid rising concerns over sea incursion along the Shangumukham coast, experts have pointed out that the diaphragm wall built to protect the Shangumukham–Airport road may actually be worsening the erosion.

Several structures, including the flight of steps and seating areas built by various departments along the beach, have already been destroyed by the advancing sea and now lie submerged. These constructions, which obstructed the natural flow and replenishment of sand, are believed to have played a significant role in accelerating the beach's destruction.

The deterioration of the Shangumukham coast began after the devastating floods that followed Cyclone Ockhi. As part of efforts to reconstruct the road connecting the airport, used by the highest number of travellers, a diaphragm wall was constructed at a cost of ₹4.39 crore. The area where the wall now stands was once part of the beach. To rebuild the road, the wall was erected and the space between it and the road was filled with earth.

According to coastal experts, this very wall has expedited coastal erosion. The presence of the wall alters the wave dynamics, forcing waves to strike adjacent areas with greater intensity, thus eroding the coast further. The 400-metre stretch of beach in front of the Old Coffee House, along with around 10 high-mast lights, concrete benches and stairways, has now been consumed by the sea.

Previously, sand washed away during the monsoon was naturally deposited back along the coast over the following months. However, experts note that the granite boulders under the sea and the concrete structures now lining the coast are disrupting this natural sand redistribution cycle.

Dr K V Thomas of the National Centre for Earth Science Studies emphasised the need to reduce wave energy offshore. “We have the successful example of the Pondicherry beach restoration before us,” he said. “To restore and strengthen the beach, sand must be deposited in a phased manner. But for this to happen, the submerged stones and concrete structures must first be cleared.”

MLA Antony Raju echoed this sentiment, suggesting that geo-tube technology could be a solution. “KIIFB has sanctioned ₹190 crore for geo-tube installation from Poonthura to Shangumukham. In Poonthura, where geo-tubes have already been installed, the intensity of sea erosion has reduced. Based on the IIT Madras report, we are exploring the possibility of installing geo-tubes to protect the Shangumukham coast as well,” he said.

Temple committee urges protection of Arattu Mandapam
Meanwhile, the administrative committee of the Sree Padmanabhaswamy Temple has served a formal letter to the Thiruvananthapuram Corporation, urging immediate action to protect the historic Arattu Mandapam at Shangumukham Beach from further sea erosion.The Arattu Mandapam holds great religious and ceremonial importance as it is the site where deities from the Sree Padmanabhaswamy Temple are brought for the ritual sea bath (arattu) during festivals.

Committee member Karamana Jayan, who visited the site, expressed grave concern over the deteriorating condition of the mandapam. "This structure, built during the reign of the erstwhile Travancore kingdom, is now under serious threat of being swallowed by the sea," he said.

Recent heavy sea erosion has already washed away the soil beneath the footpath in front of the Old Coffee House. The coastline near the Arattu Mandapam has receded significantly and if erosion continues at the current pace, buildings and monuments of historical and cultural significance could face irreversible damage.