Shoreline extraction and change estimation using geospatial techniques: a study of coastal West Bengal, India

Shoreline identification is a complicated and time-consuming process for larger and inaccessible areas such as the coastal region of West Bengal (India) using traditional and repetitive ground surveying techniques. Though the recent advancement of geospatial technologies has overcome many of these issues, low spatial resolution, mixed pixels, on-screen shoreline delineation accuracy are not entirely reliable. Moreover, coastal land changes along the shoreline, especially islands, are the major concern mainly related to mangroves destruction. normalised difference vegetation index (NDVI)-Tasseled-Cap transformation technique has been used to automatically generate shoreline using seven Landsat image pairs (1989-2018). The shorelines have been quantified and analysed by end point rate (EPR) and linear regression rate (LRR) algorithms in the digital shoreline analysis system (DSAS) add-in tool within the ArcGIS platform. The rate of shoreline change has been analysed for delineating zones of accretion and erosion. The result reveals that the coastal region of West Bengal has undergoing erosion at the rate of - 3.36 m/year and - 4.70 m/year as per EPR and LRR methods, respectively. Moreover, the study also shows the zone along the islands is more susceptible to erosion than the other zones. The island-wise shoreline study reveals except Lothian Island, the rest of the selected islands viz. Bulchery, Dalhousie, Bhangaduni, Sagar and Baghmara Reserve Forest are erosion-prone. The results would be valuable for coastal and forest conservation planners to identify the most vulnerable zones and propose appropriate policy measures.