The Hindu : Kerala / Thiruvananthapuram News : Sand-mining exposes beaches to wave fury

Online edition of India's National Newspaper
Monday, Jul 16, 2007
ePaper

Kerala

Kerala - Thiruvananthapuram

Sand-mining exposes beaches to wave fury

Special Correspondent

Scientists demand systems based on artificial reefs and green belts to protect coastline

Photo: S. Gopakumar

‘Manmade’ disaster: The raging sea invades the Shanghumughom beach in Thiruvananthapuram, threatening to wash away the airport road. -

Thiruvananthapuram: Unregulated extraction of sand from beaches and riverbeds has led to heavy depletion of the shoreline, triggering accelerated erosion along the coastal belt in Thiruvananthapuram and other parts of the State.

Encroachments and construction activities in coastal areas are also responsible for the widespread damage caused by erosion this year, according to preliminary assessment by scientists studying the situation.

Says M.Baba, Director, Centre for Earth Science Studies: “There is nothing to indicate abnormal wave action compared to the monsoon period in the previous years. Unchecked sand-mining has depleted the beaches, depriving the coast of a buffer zone to absorb the impact of the waves. This is responsible for the scale and magnitude of the damage caused by erosion this year. It also explains how the beaches at Vettukad and Pallithura, that were hitherto unaffected, now have to face the fury of the waves.”

Dozens of houses in the coastal belt from Pallithura to Panathura were destroyed over the last two weeks, forcing families to seek shelter in relief camps set up by the district administration. The relentless battering of the waves has uprooted trees and damaged roads, seawalls and other structures. The Airport- Shanghumughom beach road is in imminent danger of being washed away.

Sand cushion

According to Mr. Baba, the lack of adequate sand to create a natural cushion has exposed long stretches of the beaches to erosion.

The formation of beaches due to accretion of sand is a natural phenomenon caused by offshore transport of sediments. In the absence of adequate quantity of sediment, the process is disrupted. A depleted beach is incapable of withstanding even normal wave activity.

Scientists point out that unchecked sand-mining from Neyyar and Karamana rivers has contributed to the depletion of beach sand. The sand resources are carried down through the rivers and enter the sea through estuaries, from where they are transported by the along-shore current and distributed throughout the coast.

The reduction in sediment supply from rivers depletes the quantum of beach sand, which in turn contributes to increased erosion.

The extraction of beach sand itself compounds the problem further. The saline sand removed from beaches is favoured as a foundation-filling material for buildings because it repels termites and rodents. Unscrupulous traders also mix the beach sand with river sand to reap more profit.

Encroachments and construction of roads, walkways and parapets close to the shoreline are also identified as causative factors for the heightened erosion. Any kind of permanent enclosed structure traps sand and inhibits sediment transport. This leads to bottom erosion, damaging the structure in due course. Unless there is sufficient buffer material to absorb wave impact, the whole coast becomes vulnerable.

Scientists point out that seawalls hinder sediment travel, leading to severe erosion on the leeward side. It is the last option in beach protection and a costly proposition. They feel that the best coastal protection strategy is to preserve the beach by distancing all developmental activities and create a buffer zone for the interplay of land and sea.

The social and economic impact of the worsening erosion has triggered the demand to relocate human settlements away from the shoreline. Fishermen however fear that resettlement will leave the beaches open for the sand-mining, tourism and industrial lobbies to move in.

Curbs on sand-mining

Scientists recommend an integrated coastal protection strategy based on systems like artificial reefs and green belts. The immediate solution is to initiate a heavy crackdown to stop beach sand-mining altogether and impose strict regulations on mining of sand from riverbeds, says Mr.Baba.

The Government has announced a project to create an artificial submerged reef at Kovalam to break up large waves. The reef made of polythene bags filled with sand is dumped off the coast. “Unlike seawalls, an artificial reef aids deposition of sediments. It dissipates wave energy and minimises erosion,” says Dr. Baba.

Printer friendly page
Send this article to Friends by E-Mail

Kerala