Coastal vulnerability assessment using analytical hierarchical process for South Gujarat coast, India

The eustatic sea level rise due to global warming is predicted to be about 26-82 cm by the 2100 (5th IPCC 2013), which necessitates identification and protection of vulnerable sections of coasts. The majority of formerly developed coastal vulnerability/sensitivity indices acknowledge that the addition of socioeconomic variables would assist to identify vulnerable areas. The present study therefore is an attempt to develop an integrated coastal vulnerability index (ICVI) for the South Gujarat coast using both physical and socioeconomic variables. Five physical variables, namely coastal slope, Coastal landforms/features, Shoreline change rate, Mean spring tidal range, and Significant wave height, are used for the calculation of the physical vulnerability index (PVI), whereas four variables such as population density of adjacent coastal villages, land use/land cover, proximity to road network and settlement are used to assess the social vulnerability index (SVI). The weights for PVI and SVI are calculated using the analytical hierarchical process (AHP) method, as an improvement to the existing methodologies for vulnerability assessment. Based on the weights and scores derived using AHP, vulnerability maps are prepared to demarcate areas with very low, low, medium, high, and very high risk. The PVI and SVI values are integrated to compute the ICVI. According to the criteria of coastal vulnerability, as defined in this study, the coastal segment with low to very low risk of ICVI rating is 52.51 % of the study area, whereas 13.47 % of the coastal stretch falls under the high-to very high-risk category.