Coastal Risk Assessment

The West Bengal coastal areas are the part of Bay of Bengal (BoB), and it is geomorphologically and hydrologically dominated by the Ganga river system. This is being continually attacked by cyclones, storm surge, sea waves, sea level rise and long-shore tidal currents, which have caused terrific erosive transgression over the aerial and subaerial part of deltaic Sundarbans and littoral zones of Midnapore coast. In recent decades the coast is being ravaged by embankment breaching, submergence and flooding, beach erosion and siltation at protruding jetties and reduced channel navigation, are all aerial and subaerial hazardous processes making the coast prone to vulnerability and subsequent long-term coastal risk. Hence, the assessing of coastal risk is a crucial task for sustainable coastal zone management in terms of erosion, anthropogenic activities, violation of Coastal Regulation Zone (CRZ) rules (due to continuous erosion/accretion and lack cohesion and lobby), sea level fluctuation (due to combined effects of climatic, geologic and other physical process) and global warming and biosphere (exchange in atmosphere of trace gases). This chapter introduces the concept and background of coastal risk and different types of methodological approaches which are significant in managing the coastal environment of east coast.

The coastal areas are subjected to different types of hazards like flood, tsunami, cyclone, storm surge, sea level rise and erosion due the impacts of global climate change. In most of the events, more than one such hazard happens to occur simultaneously leading to multihazard situations. In order to optimize disaster risk reduction endeavours, it is necessary to develop an integrated framework for analysis of multiple hazards that facilitates comparing distinct administrative units or regions in regard to hazard threat. For Indian coasts, such efforts are still missing. An inclusive hazard analysis should be adopted with identification and prioritization of hazard types followed by assessing probability of the occurrence of a hazard of given intensity (or degree of severity, often associated with the physical level of damage) at a particular location. This chapter demonstrates well-developed scientific methods to analyse hazards through various steps like data collection, data analysis and mapping each of which has been implemented for the case of Sagar island.

The coastal areas, for now and forthcoming decades, are vulnerable to threats posed by coastal storms, tidal regime, sea level rise, geologic processes, changing global climate and ongoing unprecedented human encroachment. The disastrous Aila event (2009) and associated storm waves, tidal waves and coastal floods are to be remembered by the people of Sagar island for large-scale damaging activities. Hence, assessing the quantification of vulnerability is an indispensable step in disaster risk analysis. But quantification of vulnerability has always been a challenge because of its diverse types and inherent complexities in the connectedness of vulnerability variables with people’s livelihoods and poverty. In Indian context, vulnerability assessment methods vary significantly according to the nature of coastal sector under study. In the present study for mapping coastal vulnerability, a large numbers of physical and socio-economic variables have been used. It emphasizes on five groups that are likely to have least protection against hazard on the basis binomial rules. In  addition to measurement of resilience and capacity in Sagar island, the present study has also analysed  the methodological applications of coastal vulnerability in practice.

The global climate change makes the turmoil to coastal community across the globe. Hence, in the process building of community policing strategies, adaptive capacity of coastal society plays an important role to influence change in the community and a mere antagonism for the coastal community leader looking to increase effectiveness. Thus, the adaptive capacity of a coastal society is a step in building bridges between social gaps. This may include the potential, capability or ability of a system (human or natural) to adapt to hazards. It originates from four inherent or built qualities of the society-norms, reciprocity, trust and networks. The coastal socities may have little adaptive capacity to gradual changes in environmental alteration, but adaptive capacity to change in extreme coastal hazards may not be so high. The plethora of studies have been carried out to know comparative adaptive capacity and coastal vulnerability and its difficulties are well recognized and documented. Results are that the estimates of adaptive capacity tend to be based on social, political and economic premises. Highly managed system, given sufficient resources are likely to be more adaptable than less managed systems. Thus, the present chapter gives an overview about adaptive capacity of society against any turmoil and the techniques for its measurement for coastal areas.

The mapping of risk in coastal areas is an important task for coastal zone management. Recent global climate change brings overwhelming risk to coastal areas by different processes. Several studies have warned that the of coastal societies at large might be at risk of inundation and damage caused by coastal flooding, storm surge, sea level rise and extension of tidal regime, etc. The beach erosion by sea level fluctuation may be vulnerable to residential buildings. Coastal tourism industries are being faced with alarming and increasing challenges due to global climate change and should need to plan to sustainable coastal management. Hence, this chapter maps the coastal risk and it provides to the coastal managers, administrators, coastal engineers, decision-makers, practitioners and planners about future pattern and scale of coastal change and coastal risks and hazards in the West Bengal coast.