chennai scientists from the ministry of earth sciences are employing sonar signals in their attempt to map depths of ocean along the countrys 7500km long coastlineon fruition in about three years from now the highresolution coastal seabed data gathered through seabed mapping will help forecast natural disasters like cyclones and tsunami along with a host of models on environmental management and monitoring with higher accuracyexperts from citybased national centre for coastal research nccr along with those from national institute of ocean technology niot onboard research vessels are now scanning the bottom of bay of bengal to map seafloor contours up to a depth of 30m a length of about 100km along the tamil nadu coast has been mappeda comprehensive database on the topography characteristics and the depth of the seafloor on the east and the west coast of the country will be fed into complex computer models run on supercomputers to forecast tropical cyclones tsunami and coastal flooding globally seabed mapping is used to gather data for a range of scientific applications such as tsunami risk assessments hazard identification and risk modelling marine security and groundwater monitoringthe mapping is mainly being done for disaster management said nccr director mv ramana murthy a highresolution data on coastal bathymetry a measure of ocean depth is crucial for prediction of storm surge tsunami and coastal inundation as the bathymetry influences height and duration of wind waves when they hit the coast and the disturbance it may cause under water we have started with the east coast asit is more prone to tsunami and storm surge he saidexplaining the process he said jet skis fitted with sonars are scanning the seabed closer to the coast up to a depth of 6m for mapping depths from 6m to 30m fishing trawlers and research vessels sagar tara and sagar anveshika equipped with multibeam echosounders and a sidescan sonar will be deployednccr scientists said the seafloor beyond 500m distance from the coast has been mapped by the national central for polar ocean research goa also data on seabed closer to ports are available at a better resolution but thats not enough we need to have bathymetry data up to about 500m the nccr director saidat present the forecast models use digital data from naval hydrographic charts which according to nccr scientists are of low resolution with low resolution there can be an error in the forecast of wave height hitting the coast when that forecast data is used in coastal inundation models we may not get accurate results ramana said what we are working now is to map at about a resolution of 250m or below which when used in models will improve our forecastwhile the team has mapped a 100km stretch along tamil nadu coast up to 500m into the sea since the beginning of this year the real challenge scientists said is on the west coast where they may have to travel longer distance into the sea to map a 30m deep seafloor nccr is