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.
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.
India has a vast coastline of about 7,500kms which includes the islands of Andaman & Nicobar and Lakshadweep. The coastline of the mainland accounts for around 5,500kms. The entire coastal area of our country is home not only to some of the most ecologically sensitive areas but is also especially vulnerable to natural hazards like cyclones, storm surges, tidal waves etc.
Around 6 million people reside along the coastal area, of which a large part are the local communities including fisher folk families, agriculture families etc. These communities along with other structures of national importance are prone to natural hazards. During the last few years there has been an increase in the frequency of the natural hazards occuring along the coastal areas.
Hazard mapping exercises be adopted for the purpose of protecting the life and property of local communities. 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. The hazard line will be of enormous benefit in protecting coastal population and resources from cyclones, tides, tsunami. USA, UK and European countires have this system. India is taking a giant step in assuring our coastal communities a new scientific tool for a more secure future, 6 million people live in coastal zone and are affected by sea level changes. It is crucial now to understand and get real information about coast line levels.
A Memorandum of Understanding has been signed for the mapping and delineation of the hazard line along India’s coast, between the Ministry of Environment and Forests and the Survey of India (Department of Science & Technology). This initiative of the MoEF forms a critical part of its
responsibilities vis-à-vis planning and management of the coastal zone and is being done for the first time in the country. 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. Further, to obtain international experience, Prof.John Pethick, Advisor to UK Government on coastal issues was also brought in to firm up the methodology.
The Survey of India is not only a nodal agency for the map policy of the country, but is amongst the most reputed agencies in the world in the areas of survey and mapping. Also data on major parameters such as the tidal data and elevation data are available with SoI. Hence, this project is being assigned to SoI.. In this project, Survey of India will employ latest technology for mapping the hazard line.
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 total cost of the project is Rs.125crores and is expected to be completed within a period of four and a half years. Within two years from the date of signing of MoU, SoI would complete the aerial photography and thereafter would start generating maps including the hazard line.
*** SIBY
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