Tsunami Vulnerability Assessment of Cuddalore Using Numerical Model and GIS

The 2004 Sumatra tsunami left a deep and dark footprint on coastal Cuddalore in southeast India, which was one of the worst affected districts in the mainland. Assessment of natural hazards typically relies on analysis of past occurrences of similar disaster events. Assessment of tsunami hazard to the Indian coast poses a scientific challenge because of the paucity of both historical events and data. However, construction of tsunami hazard maps is the key step in tsunami risk assessment and forms the basis for evacuation and future land use planning along coastal areas. To this end, a set of inundation scenarios was built based on realistic tectonic sources that can generate tsunamis in the Indian Ocean. From historical records, three earthquake sources have been identified and a hypothetical worst case scenario was generated. Numerical models were constructed to predict the extent of inundation and run-up in each case, using a finite difference code on nested grids derived from the high resolution elevation and bathymetry datasets collected for the study area. The model was validated using field data collected immediately after the 2004 tsunami and was then used to generate the other inundation scenarios. Tsunami hazard maps for coastal Cuddalore were prepared by overlaying the numerical model outputs along with details on land use, elevation, cadastral land parcels, infrastructure, high tide line, and coastal regulation zones.