Assessment of spatial change dynamics of land features upon short and long term scenarios for a vulnerable island in the Ganges Delta

The Sagar is the largest inhabited island in the Ganges delta in India. In the recent decades the island experiences severe stress and coastal instability due to multiple setbacks such as high erosion, degradation of coastal vegetation, frequent cyclones, dynamic changes in land features and rapid population growth. This study aims in assessing the spatial dynamics of the land features of the island during the past 45 years from 1972 to 2017 as two scenarios i) Short-term and ii) Long-term to evaluate the impacts on its coastline. The extended aim of the study was to predict the status of the land features in the island for the next two decades, ie 2027 and 2037 using CA–MARKOV model. The study indicated continuous loss of land to sea and depletion of coastal features such as mangroves, mudflats and sand dunes in both the scenarios. In view of the continuous erosion of the island’s coast, protective embankments have been constructed to protect life and property. The study indicated damage of embankments due to erosion over time. Analysis of recent changes indicated that strengthening the existing embankments together with restoration of natural systems such as mangroves would minimize erosion though it may not serve as an ultimate solution to combat erosion. Based on the population density living in close proximity to such eroding coasts along with its prevailing protection measures, the study classified such stretches as hotspots of category I, II and III.