Developing a riverbank erosion susceptibility index: A pragmatic approach to reveal the level of vulnerability in coastal Bangladesh

Riverbank erosion is one of the significant natural hazards affecting the livelihoods of communities living along riverbanks in Bangladesh. This study develops a novel riverbank erosion susceptibility index (RESI) to quantitatively assess community susceptibility to this hazard. The RESI framework integrates five core dimensions: exposure, susceptibility, sensitivity, adaptability, and resilience, encompassing 34 context-specific indicators derived from household surveys, interviews, and field observations. The RESI scoring scale ranges from -1 (most resilient) to +1 (most susceptible), where higher positive scores indicate greater susceptibility to riverbank erosion. The findings in this study conclude that Chadpur Union is the most susceptible (RESI score: 0.47), followed by Shambupur (0.36) and Chanchra (0.29) union. These scores are further validated with historical remote-sensing analysis, and sensitivity tests show that varying indicator weights (equal, expert, or PCA) do not change the relative union ranking, underscoring the model’s robustness. The analysis highlights key drivers of vulnerability: frequent erosion occurrences, high population density along riverbanks, considerable losses in land and assets, and recurrent displacement due to erosion. All three unions are facing significant challenges in building adaptability and resilience, as indicated by low scores in infrastructure, financial resources, and social support systems. The study emphasizes the need for targeted interventions to reduce susceptibility, which include reinforcing protective structures, improving access to financial and technical resources, and promoting livelihood diversification strategies. Integrating the RESI into planning enables decision-makers to prioritize high-risk areas and allocate resources more effectively.