Researchers from IIT Bombay use simulations to predict future shoreline changes in Paradip Port of Odisha, India.
Among the many impacts of human-induced climate change is that it may change the shorelines across the world. Change in the intensity and pattern of winds, waves, tides, and currents threaten many cities that were once proud of their coasts. But, how exactly does climate change affect the ports on these shores, and what can port authorities do to be prepared for these changes? Using climate modelling experiments, researchers from Indian Institute of Technology Bombay have simulated what was, and what can be the state of shorelines, focusing mainly on the Paradip Port of Odisha. They have predicted an increase in the wind speed, wave height and transport of sand along the coast.
Paradip Port is a deep-water port on the east coast of India and is situated between the cities of Kolkata and Visakhapatnam. Once a mangrove swamp that was used by locals for fishing and wood collection, it is now India’s eighth major port. In the last 60 years since it started operations, the port and the coastline have been stable. However, in the recent years, they seem to be facing higher levels of erosion and deposition of sand, primarily due to climate change. Climate change refers to the change in the average weather condition over a relatively longer period of time i.e. longer than 10 years. This includes changes in sea and land temperatures, intensity and patterns of wind and rainfall.
“The impact of climate change is highly site-specific or region-specific. Whatever happens in coasts of England or Dubai will not necessarily be valid in Indian coasts. We have about 7000 kilometres of coastline, and it is not likely that the impact of climate change will be the same throughout the coastline”, remarks Prof. Deo.
The researchers of the study used a climate model resulting from the ‘Coordinated Regional Climate Downscaling Experiment’ (CORDEX), developed by the World Climate Research Program. They simulated waves in two-time slices, from 1981 to 2005 and from 2011 to 2035, and thereafter they estimated the sediment transport and shoreline changes during these time periods. The study assumes no construction or developmental activities on the coastline for the next 25 years and does not account for the increase in sea-levels due to global warming which was found to be very small in some of the previous studies. Hence, the predictions are the ‘bare minimum’ changes that can be expected at the Paradip Port.
“Impact of climate change on shorelines is not necessarily restricted to ocean parameters alone. We also have to study socio-economic parameters such as a rise in the future human population living along coastlines, evolving road networks, infrastructure, tourism, etc.”, points out Prof. Deo on the scope of the study.
The study predicts that Paradip Port may see an increase of 19% in mean wind speeds and 32% in mean wave heights in the next 25 years. Going forward, we could observe many tall waves compared to shorter waves, along with a change in their direction of attack, say the researchers. They also predict that littoral drift—the transport of sand particles towards the shores due to waves—may increase by 37% and 24% on the net and gross volumes.
In many ports across the world, a structure to reduce the intensity of wave action and thereby reduce coastal erosion, called breakwater, is built. Paradip also has two breakwaters; one to the north with a length of about 500 metres, and another to the south which is about 1200 metres long. The researchers predict that due to climate change, the shoreline to the south of the breakwaters will face a greater extent of erosion, which may go up by 4 to 8 metres compared to the current levels.
In Paradip, the port authorities are already building an offshore breakwater that is 1600 metres long to counter the current erosion. The results from this study may help them to budget and strategise the construction by making it futureproof, the researchers believe. They soon plan to discuss the predictions with the authorities of Paradip Port.
The researchers also suggest alternative strategies to minimise the effects of climate change on our shorelines. Restricting human intervention in these areas to the minimum, balancing the need for developmental activities and conservation, and following the coastal zone regulation norms goes a long way in safeguarding our coasts, they say. Also, assessing the impacts of proposed irrigation projects that could cause water-logging and intrusion of salinity, and planning for activities like beach nourishment, dune restorations, afforestation, mangrove conservation could also help.
“People must know that climate will not remain the same in the future, it will change. Most probably, it will result in intensified climatic conditions, and hence future planners of the coastal ecosystem should take into account the changing climate and devise the mitigation strategies accordingly, rather than basing strategies on past climatic conditions”, suggests Prof. Deo.