Coastal vulnerability assessment of Puducherry coast, India, using the analytical hierarchical process

Abstract

Abstract. As a consequence of change in global climate, an increased frequency of natural hazards such as storm surges, tsunamis and cyclones, is predicted to have dramatic affects on the coastal communities and ecosystems by virtue of the devastation they cause during and after their occurrence. The tsunami of December 2004 and the Thane cyclone of 2011 caused extensive human and economic losses along the coastline of Puducherry and Tamil Nadu. The devastation caused by these events highlighted the need for vulnerability assessment to ensure better understanding of the elements causing different hazards and to consequently minimize the after-effects of the future events. This paper demonstrates an analytical hierarchical process (AHP)-based approach to coastal vulnerability studies as an improvement to the existing methodologies for vulnerability assessment. The paper also encourages the inclusion of socio-economic parameters along with the physical parameters to calculate the coastal vulnerability index using AHP-derived weights. Seven physical-geological parameters (slope, geomorphology, elevation, shoreline change, sea level rise, significant wave height and tidal range) and four socio-economic factors (population, land use/land cover (LU/LC), roads and location of tourist areas) are considered to measure the physical vulnerability index (PVI) as well as the socio-economic vulnerability index (SVI) of the Puducherry coast. Based on the weights and scores derived using AHP, vulnerability maps are prepared to demarcate areas with very low, medium and high vulnerability. A combination of PVI and SVI values are further utilized to compute the coastal vulnerability index (CVI). Finally, the various coastal segments are grouped into the 3 vulnerability classes to obtain the coastal vulnerability map. The entire coastal extent between Muthiapet and Kirumampakkam as well as the northern part of Kalapet is designated as the high vulnerability zone, which constitutes 50 % of the coastline. The region between the southern coastal extent of Kalapet and Lawspet is the medium vulnerability zone and the remaining 25 % is the low vulnerability zone. The results obtained enable the identification and prioritization of the more vulnerable areas of the region in order to further assist the government and the residing coastal communities in better coastal management and conservation.

Indicator-based assessment of climate-change impacts on coasts: A review of concepts, methodological approaches and vulnerability indices

“…Socio-economic variables also need to be integrated into vulnerability assessments of the Indian coast which explains the greater diversity of parameters considered within the subcontinent (see Table 6 in Sudha Rani et al, 2015, Mani Murali et al, 2013). …”

How to Define Priorities in Coastal Vulnerability Assessment

“…The identification of more vulnerable coastal strips, where potential risks may be relatively high, has been faced in literature by applying different methodological approaches, as previously written. Among the first and widely adopted methods is the index-based one, which provides a Coastal Vulnerability Index (CVI) [15,[29][30][31][32][33] usually according to the following steps. Firstly, key parameters are identified, that is, those ones linked to the hazard, which potentially could cause an adverse effect and those ones linked to susceptibility, which make the system prone to the effects of the hazard factors [15,34].…”

“…Several studies have shown how the AHP methodology can be successfully used as a decision tool for the case of landslide hazard zoning, flood mapping and soil erosion danger mapping [30,38,39]. Nevertheless, few studies have applied the AHP methodology for the analysis of coastal vulnerability [32,33].…”

“…Coastal slope, obtained as the ratio of the altitude change to the horizontal distance between any two points on the coast perpendicular to the shoreline, is a key factor in estimating the impact of sea level rise on a target coastline and thus in evaluating land loss from inundation. Coastal areas with gentle land slope are considered highly vulnerable, since they allow abundant penetration of seawater, whereas location with steeper slopes are assumed as areas of low vulnerability, providing greater resistance to inundation due to rising sea levels and storm surges [17,32].…”

Vulnerability index and climate change: An analysis for in Cuddalore district Cuddalore District of Tamil Nadu

“…It is hence imperative to consider socio-economic variables along with environment and fishery attributes, as this would enhance the accuracy and clarity of results related to coastal vulnerability as the magnitude of a natural calamity is often described in terms of the devastation it causes to human, natural and anthropogenic resources (Mani Murali, 2013).…”