Assessment of Coastal Vulnerability Due to Sea Level Change at Bhola Island, Bangladesh: Using Geospatial Techniques

Abstract

With continued climate change, coastal areas are subjected to undesirable situations in the form of sea-level rise and its adverse outcomes like storm surge, flooding and erosion. Being a unique geographic location, low topography, relatively higher population density as well as overwhelming dependence on natural resources, Bangladesh is one of the vulnerable countries exposed to the impacts of global warming and climate change. Bhola in southern Bangladesh represents the world’s most dynamic estuary is potentially vulnerable to accelerated sea level rise and associated calamities. The present study aims to develop a coastal vulnerability index (CVI) using eight parameters namely (a) geomorphology, (b) slope, (c) relative sea level change rate, (d) mean tide range (e) shoreline erosion and accretion, (f) population (g) bathymetry and (h) coastal flooding which were addressed as the relative risk variable for the study area using geospatial techniques i.e., Remote Sensing and GIS. The aforementioned parameters were ranked on the basis of their potential contribution to physical changes on the coast, as sea-level rises, and the final calculation was done over 263.87 km shoreline by the square root of the mean values of the ranked variables. According to the vulnerability index, about 22 % corresponding to 57.23 km of the entire coast is under very high-risk and another 29 % representing 75.26 km is under high-risk. Again, 25 % encompassing 67.69 km shoreline is at moderate risk and 24 %, that is 63.69 km shoreline is found to be at low risk. The most vulnerable coastal regions are found mainly along the western coast of Char Fasson and northern and southwestern coast of Bhola Sadar of Bhola Island.