26/08/15

Erosion hits Indian Ocean island paradise

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  • Lakshadweep's blue lagoons and coral reefs threatened by coastal erosion and human activity
  • Dredging for port development and tourism promotion on the fragile islands are partly responsible
  • Study suggests harnessing wave energy to replace the islands' diesel power generators

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[THIRUVANANTHAPURAM]  A comprehensive study of the Lakshadweep Archipelago, a group of 36 coral islands lying 400 kilometres off the west coast of India, reveals severe coastal erosion that threatens the stability of the popular tourist destination.
 
The study, published in Springer Brief in Earth Sciences- 2015, depends on numerical modelling, says that that the erosion of the coral reefs is caused by natural factors such as high wave activity, strong winds and tidal currents, as well as human activity.

T.N. Prakash, head of coastal process studies at the National Centre for Earth Sciences Study (NCESS) in Thiruvananthapuram and lead author of the study, tells SciDev.Net that the low elevation of the islands makes them especially vulnerable to tidal waves and coastal flooding.
 
“The erosion can be attributed to shifting beach sediments, energy concentration due to wave diffraction and reduction in the height of reef edge," Prakash says. "The rare aquatic biodiversity and vast blue lagoons of the islands are also at risk from cyclones and deep depressions."

Lakshadweep, a part of the Chagos – Maldives – Laccadive Ridge that extends into the Indian Ocean, is considered as the northern geographical arm of the Maldives island chain. The islands have a total surface area of 32 square kilometres with a 132 kilometre-long coastline.
 
Sheela Nair, researcher for the study, says that morphological changes to the beach are reflected in changes to the shoreline. “While short-term shoreline changes are seasonal and may not lead to net annual change, long-term changes call for beach protection measures such as the use of tetra pods, hollow concrete blocks and coir bags filled with pebbles — though these may hamper fishing and tourism activities," she says.
 
Most of the islands suffer from destruction of their coral reefs, lagoons and mangroves through dredging activities for port development. Fisheries, inadequate sewage and solid waste treatment and unscientific tourism promotion on the islands, which supports a 70,000-strong native population, are also contributing to the degradation.
 
“While considering the limitation of  resources in Lakshadweep, a new management policy with indigenous initiatives, good mix of administration and  science-and technological inputs  has to be drawn up for the islands,” says Prakash.
 
The study, carried out over the 1990—2010 period, suggests harnessing wave power as a technologically and economically viable source of energy that can replace or augment the islands' diesel power generators.
 
N. P. Kurian, scientist and member of the board of studies in physical oceanography at the Cochin University of Science and Technology says that viable energy resources are vital for the far-flung territory. “This study is important for the fact that it looks into the prospects and advantages of renewable energy sources like wind and wave and for multi-source power generation systems on the islands,” he tells SciDev.Net.   
 
According to the study, the cost of wave power generation is comparable to the present cost of shipping diesel from the Indian mainland to the islands.
 
>Link to full article in Springer
 
This article has been produced by SciDev.Net's South Asia desk.