Vaan Island in Gulf of Mannar on the verge of submergence


The Vaan Island is one of the 21 islands located at the southern tip of Gulf of Mananr Marine National Park (GOMMNP) and comes under Tuticorin group. This Island has been the most affected in the last 3 decades because of coral mining, which was completely halted in 2005. The fishing grounds outside the Tuticorin group of Islands are main source of livelihood opportunity like fishing to thousands of fishermen from Therespuram, Vellapatti and Tharuvaikulam villages. Though trespassing has been restricted as per Wildlife Protection Act, still traditional fishers enter the Islands during rough weather period for temporary shelter. The Vaan island is always a great attraction in the south GOMMNP region, as is very close mainland and so researchers, officials and trainees were taken to this islands.


Erosion has been a serious threat to Vaan Island as it is shrinking in size over the years. There is a pillar near Vaan Island which is approximately 200 m away from the Island and rooted in the sea now. Thus the erosion on the Island is very obvious. As per the notification of the Gulf of Mananr Marine National Park (G.O.Ms.No.962, Forests and Fisheries, 10th September 1986), the Vaan Island was having 16 heactres of area cover. Vegetation on the Island is not noticeable as Prosopis juliflora is the dominant plant along with some small shrubs and salt marshes.


Currently the area of Vaan Island is having approximately 5.7 hectares. Recently, a month back, it has been noticed by the reef researchers from SDMRI that Vaan Island has been split in to two as sea water enters through a narrow gap of 15 m from one side of the Island to the other during high tides. The Island has been now split in to southern and northern parts. The South side is with about 2.7 hectares and north side is 3 hectares. The gap between these parts is 40 m in length and 15 m in width during the low tide. This gap seems to be increasing and it would eventually make the island with clear two portions. If the erosion acts with the same speed it is obvious that the two portions of the Island would sink in a decade time. It is to be noted that 2 (Vilanguchalli Island in Tuticorin Group and Poovarasanpatti in Keezhakkarai Group) of the 21 Islands are already under the water because of the erosion. The Vaan Island could possibly make it as 3rd Island to submerge.


The reason for the erosion could be the combination of several factors. Though coral mining was halted in 2005, the mining in the last 3 decades made instability of substratum. Corals act as a barrier to save the shore from strong waves and currents and removal of these resources made the island shore vulnerable to erosion due to currents, waves and tides. The change of current pattern due to dredging in the nearby Tuticorin harbour could be another reason. Furthermore, the change of current direction during southwest and northeast monsoons also reflects on the Island. The global climate variations have made the sea level to rise all over the world and Gulf of Mannar is also not an exception. In an already eroded Island, rising of sea level would also add to the damage. However, exact reason cannot be provided now as it needs further detailed study.


At the juncture, interventions like coral and seagrass rehabilitation would help to reduce the impact of strong waves and also Artificial reefs outside the Marine National Park boarding the Vaan island in the seaward side would help to reduce the impact due to currents and waves.