Assessment of coastal vulnerability for extreme events

The necessity to protect coastal regions from sea-level rise (SLR) and extreme events demands a rigorous assessment of coastal vulnerability. The intergovernmental panel for climate change (IPCC) predicts that climate change will severely impact the coastal region, river systems, and urban infrastructures. The changing climate is observed to be increasing the frequency and magnitude of extreme hydrometeorological conditions, such as storm surges that adversely affect coastal areas by flood inundation. This study emphasizes the need to use extreme events and socio-economic data to evaluate the Coastal Vulnerability Index (CVI) for planning and adaptation measures. Therefore, the present study utilizes spatially varying surge heights for improved estimation of the CVI, unlike the constant surge heights considered in the previous studies. For coastal adaptation measures, synthetic cyclones of different return periods, such as 20-, 50- and 100-year, are simulated using a hydrodynamic model to represent a range of risk and vulnerability in the estimated CVI. The proposed methodology for calculating the CVI is demonstrated by considering the Chennai coast in the state of Tamil Nadu, India. The use of spatial distribution of storm surges from hydrodynamic simulations makes the CVI more realistic. Such thorough assessments utilizing high-resolution CVI maps can help policymakers suggest appropriate measures for specific coastal zones, which are more devastatingly affected by shoreline erosion, SLR and storm surge. The vulnerability assessment indicates that great care is needed in the planning and adaptation of the coastal ecosystem to extreme events for the safety and well-being of coastal populations and infrastructures.