A quantitative approach for geographical vulnerability assessment of Bhasan Char, Bangladesh, using Remote sensing and GIS

Abstract

The relocation of 100 thousand Rohingya refugees is expected from camps in Cox’s Bazar to Bhasan Char (BC) (island), Bangladesh. The BC is located at the mouth of the Ganga-Brahmaputra-Meghna river system in the Bay of Bengal, ⁓30-40 km from the nearest water port of the mainland. This study aims to assess geographical vulnerability based on frequent erosion and deposition of the island. Therefore, Landsat satellite images during 1975-2020 are used to detect the areal changes using Geographic Information System (GIS). Since the BC didn’t appear 20 years back, nearby islands are studied as similar geographical characteristics. A normalized difference water index is applied to identify the land area. Further, the erosion-deposition and migration of shorelines are identified and quantified. The islands are expanded since 1975. Most erosion occurs along the direction of the main flow of upstream water and the islands’ southern face, including BC. Temporarily, a settlement at BC may be no harm by maintaining engineering works of infrastructure, e.g., cyclone against standing buildings, tidal wave, and surge-protected infrastructures. However, the most important, sustainable components, e.g., economic stability and social interaction among the refugees in BC and camps in Cox’s Bazar, need to be implemented.