Sea Level Rise and Shoreline Change under Changing Climate Along the Indian Coastline

The climate change induced by global warming is predicted to change the rate of sea level rise (SLR) and that of shoreline shifts. In this study, the SLR as well as the resulting retreat of shorelines has been predicted at a series of locations along the Indian coastline to understand the future of India's beaches. The beach segments near 13 major ports where increasing infrastructure requirements are likely to arise in future are considered. The future SLR is predicted on the basis of an ensemble of general circulation models corresponding to stabilized and worst-case global warming scenarios. This showed that the rate of absolute SLR would be in the range 3.38-5.16 mm/year with a mean of 4.56 mm/year for the stabilized scenario called representative concentration pathway (RCP)-4.5 and 5.36-7.2 mm/year with a mean of 6.63 mm/year for the worst-case RCP-8.5 at the selected locations. The maximum rate of SLR could be experienced near the New Mangalore port area while the minimum could be seen near the Chennai and Ennore ports. Additionally, Cochin and Tuticorin ports could also experience the same SLR as the New Mangalore port for the RCP-8.5 scenario. The shoreline recession in response to SLR was evaluated using Bruun's rule. The results of Bruun's rule indicated that the future recession of shorelines at selected coastal stretches might vary between 14.10-29.22 m and 21.05-45.40 m up to the year 2100 for RCP-4.5 and RCP-8.5 respectively. Similarly, by this time, area-wise maximum horizontal inundation could happen near the Mumbai port region, although it is the Port Blair area where the maximum percentage increase in horizontal inundation could be experienced for both the scenarios. In general, as compared to the west coast locations, the east coast sites would undergo smaller area inundation due to relatively lower SLR and resulting shoreline change.