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

Global coastal catchments experience peculiar flood risk attributes due to the confluence of multiple flood drivers. In these regions, the monsoon and post-monsoon seasons impose diverse flood risks that evoke meticulous research for the prudent execution of appropriate flood management options. For the first time in flood management literature, we develop an integrated approach to quantify the distinguishing nature of flood risks during both seasons. We employ 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 and (b) multi-hazard risk index 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. © 2024 The Author(s). Published by IOP Publishing Ltd.