Coastal Vulnerability Assessment

By Accommodation Times News Services

OLYMPUS DIGITAL CAMERAEarth System Science Organization (ESSO) – Indian National Centre for Ocean Information Services (INCOIS), Hyderabad and ESSO-Integrated Coastal and Marine Area Management (ICMAM), Chennai have carried out mapping and demarcating of multi-hazard coastal vulnerability for the states. The relative vulnerability of different coastal environments is essentially quantified at a regional to national scale using basic information on seven risk variables, viz. shoreline change rate, sea-level change rate, coastal slope, mean significant wave height, mean tidal range, coastal regional elevation and coastal geomorphology. Most of the above parameters are dynamic in nature and require a large amount of data from different sources to be acquired, analysed and processed.

The general trend in the vulnerability, demarcated in to four classes (very high, high, medium and low), carried out first time on macro-synoptic scales (at 1:1,00,000) covering the entire Indian coastline suggest varied degrees of vulnerability along coastal states of Tamil Nadu, Andhra Pradesh, Odisha, Kerala, Maharastra, Goa, Gujarat and islands of Andaman and Nicobar Islands and Lakshadweep. The Gulfs of Kambhat and Kachchh in Gujarat show very high vulnerability indices, with the inlets of Kachchh showing localized vulnerability. Relatively low vulnerability indices are reported along the zones of Mangroves that help in breaking the large amplitude waves, dissipating the energy and hence act as a natural barrier. However, it is to be noted that coastal vulnerability aspects at a much local (micro) level are to be accounted with additional parameters such as cyclone, storm surge and coastal flooding so as to add an additional dimension to the current study.

Sea level rise is a very slow phenomenon and can be because of physical factors like normal subsidence, coastal erosion and siltation of river channels along the coastline apart from global warming. However, the trends of sea level rise as estimated to be 1.3mm/year along the Indian coasts during the last 40-50 years. However, longer term sea level data is required over the north Indian Ocean (Bay of Bengal, Arabian Sea etc.) to capture the signal of faster rising sea level.

On the global scale, Fifth Assessment Report (AR5) of Intergovernmental Panel on Climate Change (IPCC) suggests that global mean sea level has risen by 0.19 m over the period 1901-2010. The Report also suggests that sea level rise takes place in the background of several other physical factors like tsunami’s, storm surges and tidal variations, swells, normal deltaic subsidence, coastal erosion and siltation of river channels along the coastline. ESSO-INCOIS and the Survey of India continuously monitor the sea level measurements all along the Indian coastline.

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