Tsunami of 2004 had battered the country’s East Coast facing the Bay of Bengal more, whereas the West Coast facing the Arabian Sea was affected to a less extent. This coastline from Bengal down to Tamil Nadu and Kerala, continues to be vulnerable to storm surge, sea erosion and inundation when compared to the West Coast extending from Gujarat to Kerala, say top ocean scientists.
“The coast of Bay of Bengal is more vulnerable as it is more shallow when compared to the coast along the Arabian Sea. The closeness of Western Ghats to the West Coast keeps the coastal region slightly elevated. The wave heights, plentiful rivers and and more rivulets on the East Coast makes it vulnerable to higher erosion and inundation,” said former Director of Indian National Centre for Ocean Information Services (INCOIS) Satheesh S. Shenoi.
In a recent exclusive interaction, Dr. Shenoi, now Chair Professor/ Scientist in the Ministry of Earth Sciences (MoES), also stated that the number of man-made ports and harbours could also play a role in faster sea erosion and inundation. “This is the pattern across the world. For instance, Pondicherry saw rapid erosion of the beach due to the construction of fishing harbour. It has been partially restored with the mitigation efforts suggested by the National Centre for Coastal Research (NCCR) including a submersed reef”, he explained.
INCOIS has also successfully completed ALTM - Airborne Laser Terrain Mapping, on the West Coast from Gujarat to Kochi in association with the National Remote Sensing Centre (NRSC) when a similar exercise was completed along the East Coast from Bengal to Kerala some time ago.
Another key work under way is the Bathymetry study or the mapping of the sea floor 50 metres from the shoreline using small boats equipped with echo-sounders to determine the depths for the East and West Coasts. This project has been completed on the East Coast under the guidance of the National Institute of Ocean Technology (NIOT) and NCCR.
“These works got delayed due to the COVID pandemic as scientists could not move. Data processing,which is a complex process, will be taken up now, following which integration with the existing maps willbe done,” he said. If there are no more pandemic disruptions, within a year or so, the country will have a high resolution and precise mapping of the coastal region allowing scientists togive accurate assessments of the wave heights and inundationsy, informed Dr. Shenoi.
“We have been using topography data supplied through the National Aeronautics and Space Administration (NASA) and later the indigenous satellite data from ‘Cartosat’, already integrated into the Tsuanami warning system. We are aware there are inaccuracies, which we expect to overcome with emerging data which will improve the prediction of shallow water velocity, length and height of waves etc,” he said.
The ocean institutes monitoring the quality of the sea say that pollution levels have not reached “alarming levels” so far in terms of transparency, oxygen saturation, chlorophyll, faecal coliform, etc.
Yet, presence of cadmium, copper, mercury, zinc lead, arsenic, chromium and others was detected.
“Every country has its own threshold standards, but we need to be careful in controlling the untreated sewage of cities into the sea. A pilot study on plastic pollution too has just begun through NCCR,” added the senior scientist.
