Exposed Submarine Cables Threaten Power Supply to 350,000 Residents on Sandwip Island
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Two critical submarine power cables supplying electricity to Sandwip island from the national grid have been exposed due to severe riverbank erosion along the Sandwip Channel. The cables, which were laid beneath the seabed, have remained uncovered for approximately three months, leaving about 40 feet of the infrastructure visible during low tide and raising concerns over a potential power blackout for the island’s 350,000 residents.
The Bangladesh Power Development Board (PDB) has yet to conduct an engineering assessment to determine the extent of the damage or identify how much of the cabling remains compromised under the water. The cables, which have an expected lifespan of 50 years, have been the island’s primary power source since 2018. While the system is designed to supply 50 megawatts, it currently transmits 10 megawatts through a single cable.
The PDB reports that it is waiting for a site inspection by the original contractor, the Chinese firm Jiangsu Zhongtian Technology Co. Ltd. (ZTT). However, ZTT has not arrived, citing unresolved demands regarding financial, accommodation, and logistical support. PDB officials stated they are seeking ministry approval to fulfill these conditions to facilitate the inspection.
The erosion is occurring near Bauria Union’s Ward 5, approximately 1.5 kilometers from the landing station. Initial efforts by the Bangladesh Water Development Board to mitigate erosion using geo-bags proved ineffective, and subsequent high tides in mid-July caused further exposure. Kamal Uddin Ahmed, Chief Engineer of PDB Chittagong (Distribution South), confirmed that authorities are coordinating with local administrations and the Water Development Board, but the lack of contractor intervention remains a significant hurdle.
Engineering experts warn that the cables are now in a “free span” state, where they lose soil support and hang suspended in the water column. In this state, cables are subjected to mechanical stress from currents and wave-induced vibrations, which can lead to structural fatigue. Studies published in journals such as Frontiers in Built Environment and Ocean Engineering highlight that such conditions significantly increase the risk of cable deformation and failure, particularly during extreme weather events like cyclones.
The project, completed in 2017 at a cost of 1.44 billion BDT, involved laying two 30-kilometer, three-core cables at a depth of six meters. The Institute of Water Modelling (IWM) served as the consultant for the project, overseeing the geological and morphological surveys. Despite the current crisis, PDB has not consulted with the IWM to assess the risks posed by the channel’s changing landscape.
IWM Executive Director Amirul Islam stated that PDB has not reached out for an evaluation. He emphasized that given the nine years that have passed since the original survey, the environmental conditions have likely shifted, making regular monitoring of the submerged infrastructure essential for maintaining power stability on the island.
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