A Remote Sensing Assessment of Spatio-Temporal Dynamics of Coastal Ecosystem: Evidence from Indian Sundarbans

Abstract

The Sundarbans is the largest contiguous mangrove ecosystem in the world located in the southern part of West Bengal, India and Bangladesh, and lies on the delta of the Ganges, Brahmaputra and Meghna rivers in the Bay of Bengal. Owing to its unique geographical location, this world heritage site is highly vulnerable to climate change. Despite the value and vulnerability of the coastal delta, very little data exist on the spatio-temporal dynamics of the land and the impacts of anthropogenic and natural disturbances of the ecosystem. Under the global climate change and the related sea level rise, we explored the spatio-temporal dynamics of the changing coastline and assess the vulnerability of the region. Multi-temporal Landsat imagery was used for studying land use/land cover dynamics and shoreline changes in Sundarbans. Out of the total 7300 km² study area of the Indian Sundarbans, total erosion and accretion was 163 km² and 149 km², respectively, from 1975 to 2015 and net change was an erosion of 14 km². The land use–land cover dynamics indicated that in Sundarbans, mangrove forest remained more or less stable since 1975, whereas the aquaculture and cropped area during rabi season increased considerably and fallow area decreased. The salinity map indicated that there was shifting in soil salinity from west to east during 1973–2015 because of increased rabi cultivation in the western part of Sundarbans, whereas increased brackish water aquaculture in the eastern part increased salinity in the region. The village-level climate change vulnerability in the agricultural sector of the Indian Sundarbans region was estimated using spatially aggregated biophysical and socio-economic parameters by applying the equal weight method. The results indicated that the villages in Sandeshkhali-I and II and Minakhan of North 24 Parganas was under the highly vulnerable zone. Out of 1074 villages in the Sundarbans, 139 villages covering an area of 587 km² with a population of 5.64 lakhs were found to be highly vulnerable to climate change.