The government on Wednesday initiated mapping and delineation of the "hazard line" along India's 5500-km long coastline to study impact of the global warming and assist in protecting coastal communities and infrastructure.

The study will be done within a span of four-and-half years using an aerial mapping system by the Survey of India through a World Bank-funded Integrated Coastal Zone Management (ICZM) project.

A memorandum of understanding in this regard was signed here on Wednesday by the Survey of India and the environment and forest ministry in the presence of MoS for science Prithviraj Chavan and MoS for environment Jairam Ramesh.

The project in the first phase will focus on three of the eight coastal states -- Orissa, Gujarat and West Bengal. Projects in other coastal states will also be prepared immediately and taken up for implementation in a phased manner.

The mapping, being undertaken for the first time at a cost of Rs 125 crores, will include collection and presentation of data on identifying flood lines over the last century and predictions of the erosions to take place over the next 100 years.

The special focus of the project will be identification and demarcation of coastal fragile areas like mangroves, brackish water wetlands and coral reefs, based on which a new category of "Critically Vulnerable Coastal Areas" (CVCAs) would be designated and appropriate management plans implemented for their preservation and regeneration.

"The project assumes special significance in the context of climate change since one of the definitive findings of the Inter-governmental Panel on Climate Change (IPCC) relates to the increase in mean sea levels as a result of global warming," said Jairam Ramesh. He said the hazard mapping will mark the danger areas due to global warming and will be based on four factors -- receding shore lines, waves, tides and mean sea level rise. It will also cover vulnerability to natural hazards like cyclones, storm surges and tidal waves.

The mapping will help around 60 lakh people residing along the coastal areas as also the infrastructures of national importance on the coasts. The hazard mapping exercise was recommended by the M S Swamianthan Committee set up to strengthen the existing CRZ notification of 1991.

The methodology for demarcating the hazard line has been worked out in consultation with reputed national institutions like Survey of India (SoI), Space Application Centre (SAC), Ahmedabad, Department of Ocean Development, Chennai and Centre for Earth Science Studies (CESS), Thiruvananthapuram. Also, to obtain international experience, Prof. John Pethick, Advisor to UK Government on coastal issues ,was also brought in to firm up the methodology.

The process will involve collection of historical tide gauge data to determine 100-year flood levels, analysis of maps and satellite imagery since 1967 to predict the erosion line over the next 100 years and transfer of the hazard line to topographic maps for public dissemination.

Within two years, the Survey of India would complete the aerial photography and thereafter would start generating maps including the hazard line. The mapping of the hazard line has been also incorporated in the coastal zone management planning under the draft CRZ notification, 2010, issued on May 20 for inviting public comments.

The World Bank-assisted project under which this work is being underaken also includes establishment of a National Centre for Sustainable Coastal Management at Chennai (Rs.166.28crs), ICZM projects in Gujarat (Rs.298.34crs), Orissa (Rs.201.62crs) and West Bengal (Rs.300.26crs).