SV Krishna Chaitanya By Express News Service CHENNAI: A major exercise is underway along the east coast in the country, starting from Tamil Nadu, which will go a long way in accurately forecasting killer waves. For the first time, the country is carrying out shallow-water bathymetry (study of underwater depth of ocean floors) which is the crucial ‘missing’ link in ocean and wave forecasting. The Ministry of Earth Sciences (MoES) has mandated two of its Chennai-based research units - National Institute of Ocean Technology (NIOT) and National Centre for Coastal Research (NCCR) - to develop bathymetry data along the Indian coast on priority. NCCR director MV Ramanamurthy told Express that the mammoth exercise had begun from Tamil Nadu, where 100 km of coast had been mapped so far, and in two years, the entire east coast would be covered. “Mapping of shallow water bathymetry from coast to 30 metres’ water depth is critical for disaster management during storm surge, tsunami and flood forecast modelling. The high-resolution data will enhance the accuracy of the coastal inundation and forecast models.” India does not have reliable bathymetry data. Some mapping is done in deep seas in Exclusive Economic Zone (EEZ), but nothing close to the coast. Ocean forecasters are currently using publicly available international data sets generated by the United States and International Hydrographic Organisations (IHO) such as ETOPO and GEDCO to run the forecast models. These data sets are not so reliable as they interpolate information from different sources. The National Hydrographic Office (NHO) has also bathymetry charts for navigation, but again forecast models are showing frequent errors, said scientists of the Indian National Centre for Ocean Information Services (INCOIS), which does ocean and wave forecasting. When contacted, Satish C Shenoy, director, INCOIS, acknowledged that lack of bathymetry data was a cause of concern. “There is a higher error rate in our forecasting due to this missing information. There are errors in terms of wave height. Tsunami wave or the normal wave’s height undergoes changes depending on the bathymetry. For long, INCOIS has been demanding bathymetry data.” Scientists said a combination of jet skies, fishing boats and large NIOT research ships are being used to conduct the study, depending on the depth. “For first 5 metres, jet skies are used to deploy single beam sonars and upto 20 metres fishing boats are used and going deeper NIOT vessels are deployed that are equipped with multi-beam sonars.”A naval officer told Express the data is essential for armed forces. “For deployment of amphibian forces or any underwater operation, it is critical to have our own shallow-water bathymetry data.” Need for bathymetry India does not have reliable bathymetry data. Some mapping is done in deep seas in Exclusive Economic Zone (EEZ), but nothing close to the coast. Ocean forecasters are currently using publicly available international data sets generated by the United States and International Hydrographic Organisations such as ETOPO and GEDCO to run the forecast models. These data sets are not so reliable Major exercise is on Satish C Shenoy, director, INCOIS, acknowledged that lack of bathymetry data. Scientists said a combination of jet skies, fishing boats and large NIOT research ships are being used to conduct the study, depending on the depth. “For first 5 metres, jet skies are used to deploy single beam sonars and upto 20 metres fishing boats are used and going deeper NIOT vessels are deployed that are with multi-beam sonars.”

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