Besides ports, dredging is undertaken in a number of other areas such as rivers, canals, lakes, dams/barrages, lagoons as well as sewerage and drainage systems. There are numerous reasons for dredging these waterbodies such as flood control, irrigation, bank protection, inland navigation, supply of water to industries, land reclamation for human settlement, construction of roads and development of industries. However, the key reason for dredging in inland waterways is the development and maintenance of a fairway for shipping and navigation to promote inland water transport.
So far, the Inland Waterways Authority of India (IWAI) has primarily awarded dredging contacts on an operation and maintenance and rate-contract basis. More recently, it has started exploring the option of assured-depth contracts.
Compared to deep water/port dredging, inland dredging at shallow depths is more complicated and challenging mainly on account of the varied characteristics of inland waterways. The key issues and challenges faced while dredging in these waterways can be broadly classified into two categories – waterways-related issues and general issues.
Some of the waterways-related issues are the non-availability of detailed soil characteristics of the area to be dredged; lack of detailed information on the presence of contaminated soil, sewage and radioactive materials; inadequate information on the breaching behaviour of soil, current velocity of water, the dimension of the shoal and its location as well as the behaviour of sediments.
The general issues faced while dredging can be subdivided into three categories – measurement-related issues, logistics-related issues (especially in remote locations) and land issues. Measurement-related issues arise as no standard and effective procedure on quantity measurement is available due to fluctuations in the water level, resiltation and scouring. Further, there is no standard procedure for fixing the chart datum (level of water from which charted depths are measured) in both pre- and post-dredging surveys. Some of the issues related to logistics in remote locations are the lack of water, electricity and supply of other equipment besides the dredger. The non-availability of disposal and dumping grounds, bank erosion and legal issues with respect to dredged materials are some of the land-related issues faced while dredging.
The lack of availability of skilled manpower is another key concern. The absence of a dredging policy and incentives for the segment add to the woes. Further, dredgers that are available are of obsolete design with outdated machineries and most of them do not have any registration or valid survey certificates from the relevant authorities.
Despite the issues, there are a number of opportunities in the inland waterways segment. Dredging has received a major boost with the passage of the National Waterways Bill, 2015, which aims at developing 106 national waterways (NWs) within the next 10 years, in addition to the five existing waterways. Approximately, 204 million cubic metres (mcum) of dredging volume has been assessed for the existing five waterways as well as the 40 waterways of the 106 NWs that have been proposed for development. Further, significant dredging opportunities are available along the 1,600 km Indo-Bangladesh Protocol routes and other state waterways in the country.
Going forward, there are ample opportunities available for the dredging industry in areas besides ports, such as inland waterways, dams, etc. However, the formulation of a dedicated dredging policy, the provision of financial incentives and a proper standard operating procedure are required to realise the full potential of the sector. w
Based on remarks by Ashis Kantha, Director, Business Development,
Global Marine Infratech Private Limited, and a presentation by Subhakar Dandapat, Former Chief Engineer, IWAI