EXPLORING VULNERABILITY TO COASTAL EROSION AND LOCAL COMMUNITY ADAPTATION IN CHATTOGRAM, BANGLADESH

Abstract

Due to the dynamic system, coastal areas are prone to multiple types of hazards. The location of Bangladesh's coast is more dynamic and considered to be one of the most vulnerable in the world because every year different natural disaster causes a large number of casualties and damage. In the context of the sea levels rise and other coastal hazards, it is important to assess the coast's vulnerability to erosion hazards to take the required precautions to protect people and property. A location-specific index for assessing vulnerability has very rarely been developed by combining socioeconomic variables with physical variables. The main goal of this thesis is to comprehensively assess Chattogram's coastal erosion vulnerability, quantifying the extent of erosion and understanding the adaptive strategies employed by local communities to inform resilient and sustainable coastal management. In this study, Coastal Erosion Vulnerability Index (CEVI) was quantified for the Chattogram coast with the extensive use of geospatial technologies. The CEVI was estimated using fifteen coastal Erosion vulnerability assessment factors which include seven physical factors- Elevation, Slope, Geomorphology, Soil texture, Proximity to the coastline, Coastal vegetation, Soil Permeability and eight socio-economic factors Population Density, Land Use and Land Cover (LULC), Dependent Population, Tourist spots, Road Network, Literacy Rate, Proximity to health facilities, Physical Settlement. For the calculation of the weightage of each factor, the Principle Component Analysis (PCA) method was used for this study. Physical vulnerability, driven by proximity to the coastline and soil texture, plays a dominant role, contributing 78.23% to overall vulnerability. Socio-economic vulnerability, influenced by factors like road buffer and literacy rate, contributes 21.77%. The most vulnerable vii areas encompass Sitakunda, Banshkhali, and Mirsharai upazilas, which require urgent interventions; in contrast, regions like Khulshi and Bayejid Bostami show low vulnerability. The model is highly accurate, with an AUC of 0.909, offering reliable predictions for disaster preparedness and mitigation efforts. The Weighted Average Index (WAI) from household surveys measured coastal erosion impacts, while an Adaptation Strategy Index (ASI) and an Entropy-based method evaluated adaptation strategies to establish overall adaptive capacity. Findings reveal severe erosion in several unions, with rates as high as -79.87 m/year, largely influenced by sand extraction, mangrove deforestation, and ship breaking activities. Conversely, some areas exhibit sediment build-up due to hydrodynamic forces. Results indicate that communities face persistent risks from erosion, exacerbated by inadequate management, high water velocity, storm surges, and cyclonic disturbances. This study emphasizes updated coastal policies, ecosystem-based adaptation, and integrating traditional and scientific knowledge for erosion control, guiding sustainable management in the Chattogram coast and similar regions.