Do disparities exist in flood risks during monsoon and post-monsoon seasons? Comprehending diametric behaviors over coastal multi-hazard catchments

The authors develop an integrated approach to quantify the distinguishing nature of flood risks during both seasons. The study utilizes a sophisticated 1D–2D coupled flood model to generate high-resolution flood hazards while considering the compound interactions between rainfalls and storm-tides. Flood vulnerability is mapped at the finest administrative scale while considering flood-susceptible physical and socio-economic indicators. With the concept of Bivariate Risk Classifier, we introduce two novel metrics: (a) area index (AI) and (b) Multi-Hazard Risk Index (MHRI) that advance our understanding of the multi-hazard nature of flood risks during monsoon and post-monsoon seasons. These incisive indices propound case-specific flood management measures for long-term resilience.

The study finds that the proportion of villages under severe hazard classes is higher during the post-monsoon period than during the monsoon period. This approach in quantifying flood risk during the monsoon and post-monsoon periods independently promises to deliver invaluable information to flood control authorities, enabling them to rationalize budget-specific and season-specific flood management measures.