Monday, May 9, 2011

Mapping India’s Coastal Hazard Line

Mapping India’s Coastal Hazard Line

By Dr Nandkumar Kamat

Sea levels rise and fall in geological history. People in Goa would not believe that the beach at Siridao was once located near the present highway or villages like Chicalim and Sancoale in Marmagoa taluka, Keri and Tuem in Pernem and Camurlim in Bardez were once submerged under water except the hilly portion.
The late historian Anant Dhume had claimed that he located a marine fossil – a conch buried at Thane village in Sattari which is several hundred metres above present sea level. The falling sea level benefited human migration towards the coast.
Now it is the turn of the sea to move interiors and may be for the humans to move slightly away from the predicted hazard line. A hazard line is not like the high tide line. It would mark the area which is highly vulnerable to rising sea level and other erosive forces detrimental to human lives and property. The slowly rising tidal levels are already indicating the intention of the sea.
India’s coastline is highly vulnerable to ecological and geological hazards. Goa’s reputed and proactive oceanographer Dr Antonio Mascarenhas has done a lot of research on this aspect before and after the Asian tsunami struck India. If coastal planners were to take his suggestions seriously then we could have had some sense driven into land-use-planning on India’s west and east coasts. Coastal people and panchayats in Goa need to take note of the recent CRZ draft notification (available from MOEf website in English, Marathi and Konkani) and rush to submit their comments before May 30, 2010. Thereafter, the draft CRZ Notification, 2010 would be issued under the Environment (Protection) Act, 1986.
In this draft CRZ Notification, 2010, the hazard line mapping has been incorporated in the coastal zone management planning. The almost linear and densely settled Salcete coastline has recently emerged from the sea and would need systematic hazard line planning. Otherwise people would be sandwiched between the rising waters of the sea from the west and the overflowing flood plain of the highly silted river Sal from the east. After the IPCC report on global warming and climate change it has become essential for countries which are vulnerable to natural calamities to prepare in advance.
A huge area of India’s 7500 kms coastline is only a few metres above the mean sea level. Most of the coastal towns in Gujarat have been located close to the Arabian Sea. Several cities and towns on the west coast - Surat, Mumbai, Alibagh, Malvan, Panaji, Karwar, Mangalore, Cochin, Chennai, Vizag are vulnerable to rising sea levels. So the government of India has a sense of urgency. The ministry of environment and forests (MOEF) led by a dynamic minister with independent charge, Mr Jairam Ramesh has taken the initiative to collaborate with Survey of India for delineation of the hazard line along India’s coast. The total cost of the project is Rs 125 crores. It would be completed within a period of four and a half years. Within two years from the date of signing of MoU, Survey of India would complete the aerial photography and thereafter would start generating maps including the hazard line.
According to the information provided by MOEF - “Under this project the hazard line for the mainland coast of India will be mapped and delineated. This will include the collection and presentation of data on identifying flood lines over the last century (which includes sea level rise impacts), and a prediction of the erosions to take place over the next 100 years. This process will involve: (i) Surveys and preparation digital terrain model for the entire mainland coast; (ii) Collection of historical tide gauge data and its analysis to determine 100 year flood levels; (iii) Analysis of maps and satellite imagery since 1967 to predict the erosion line over the next 100 years; (iv) preparation of composite maps, showing the hazard line on the digital terrain model, and; (v) Transfer of the hazard line to topographic maps for public dissemination. Once the hazard line is delineated, ground markers will be constructed. This is important as the revenue maps used for local planning purposes are not comparable to topographic maps.”
The hazard line mapping and delineation is required for mainland and island coastline as these are vulnerable to natural hazards like tsunamis, cyclones, storm surges, tidal waves, etc. 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.
MOEF also solicited the expert technical advice of Prof John Pethick, Advisor to UK Government on coastal issues to improve the methodology. Survey of India is more than a century old reputed organisation. The coastal hazard line mapping project is one of the components of the World Bank - assisted Integrated Coastal Zone Management (ICZM) Project to be implemented by the MoEF. MOEF would also establish a National Centre for Sustainable Coastal Management at Chennai by spending Rs 166 crores and undertake ICZM projects in Gujarat (Rs 298.34 crores), Orissa (Rs 201.62 crores) and West Bengal (Rs 300.26 crores).
MOEF also plans to also prepare projects in other coastal states immediately and take these up for implementation in a phased manner. There was no action on a report commissioned by Dept of science and technology, Govt of India through NIO to assess the impact of sea level rise on Goa in 1992. Two scenarios were projected - one and two metre sea level rise. Another report by TERI had estimated about five percent geographical area of Goa to get submerged. It was the largest in India. That makes coastal areas of Goa ecologically extremely hazard prone. To compensate for loss of 15000 hectares of land Goa has no provision of surplus land for resettling the people. Hazard line mapping would help the local communities to plan their future course of action.
People the world over are slowly trying to move away from the vulnerable coasts. Hazard line mapping is a scientifically sound way of incorporating disaster preparedness in land use planning. Goa needs to take this concept and idea seriously to safeguard life and property.

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