Coastal erosion and its management in Sagar Island, South 24 Parganas, West Bengal

Sagar island (Hugli estuary : 21°37'–57'N, 88°02'–11'E) was started to be reclaimed from the Sundarban mangrove wetlands in 1811. Mainly due to different Government policies the island gradually became almost completely settled with a population of 149,222 (1991), naturally growing at 3.99% per year. Coastal erosion, that reduced the total supratidal area of Sagar by about a quarter within 144 yr (from 284.55 km² in 1851-55 to 219.26 km² in 1997), forms the most important natural environmental hazard (NEH) affecting the island. Among other things, the erosion can primarily be related to the disturbance of morphological steady state of the Hugli estuary due to reclamation of its intertidal areas. Most of the erosion takes place episodically during tropical cyclones - the severe types of which (Beaufort force 10 or above) have a recurrence interval of 3.28 years within 100 km of the island. The erosion management schemes of Sagar, managed by seven different agencies, include 74.5 km of marginal embankments (19.4% brick-paved), 579 ha of mangrove plantations in 11 localities and three relocation settlements. Their efficiency range from excellent to very poor. To ameliorate the existing schemes, the available resources need to be used more rationally and optimally with proper appreciation of the natural feedback mechanisms. Brick-paving of the river-facing earthen embankments and different designs for the sea-facing dykes should be considered. Formation of an apex management coordinating agency/body is also necessary. In the long run, socio-economic development, that reduces vulnerability to the NEHs, may become the best option for alleviating the erosion hazard.

[] Bandyopadhyay, S., 1997, Coastal erosion and its management in Sagar island, South 24-Parganas, West Bengal. Indian Journal of Earth Sciences, 24(3-4), 51–69. https://doi.org/10.5281/zenodo.7264120