Among the major ports in the country, the Kochi Port required the highest quantity of annual maintenance dredging to maintain its draft in the last three years.
According to statistics available with the Ministry of Ports, Shipping and Waterways, around 72.5 million cubic metres (MCUM) was dredged at the port followed by Jawaharlal Nehru Port Authority, Mumbai, (50.16 MCUM), Syama Prasad Mookerjee Port Authority, Kolkata, (25.6 MCUM), and Paradip Port Authority, Odisha, (21.21 MCUM).
Maintenance dredging assumes significance as port administrations need to spend a huge amount for dredging and disposal of dredged material. As per figures, around 24 MCUM of dredging is done annually at the Kochi Port for maintenance of channels, making it one of the most expensive ports in the country in terms of annual maintenance cost.
Though it is one of the serious problems faced by the ports along the east and west coasts in the country in terms of operational and environmental concerns, the quantity of silt to be dredged will vary from port to port depending upon its geographic location and draft required to be maintained for the passage of vessels, according to senior officer close to the Cochin Ports Authority. Here in the case of Cochin Port, the annual maintenance dredging is relatively high recently compared to other major ports.
First, it is situated in a tidal estuary where tidal forces such as flood tide and ebb tide are the predominantly acting on the port basin. The presence of marine clay along the river mouth is posing serious challenges along with the silt deposited by the Periyar River in harbour basin. However, the cost involved for the maintenance dredging is significantly low here as marine clay has a significant amount of water and the tonnage of silt in marine clay is about fifty per cent lower than other dredged materials such as sand.
Further, the Cochin Port has spent around ₹120-140 crore for the annual maintenance dredging, which is not a big deal considering the 40-million tonne cargo it handles per year, said the sources. In the proposed Vizhinjam international seaport, the maintenance dredging is anticipated almost nil due to its natural drift while it has to undertake a capital dredging of 7 MCUM to arrange infrastructure facilities.