Global flood risk dynamics and their coupling with sustainable development goals (2000-2024)

Global flood risk has intensified dramatically since 2000, yet its alignment with disaster-related SDGs remains unclear, limiting our understanding of how to effectively reduce it. This study develops a composite Flood Risk Index (FRI) based on the hazard - exposure - vulnerability framework and constructs comparable SDG sub-indicator scores for six disaster-related metrics. Using data for 111 countries from 2000 to 2024, long-term trajectories were evaluated via OLS regression slopes, and structural turning points were detected through a Pruned Exact Linear Time (PELT) algorithm for both FRIs and SDGs. Results show a persistent global rise in flood risk, predominantly driven by hazard intensification throughout the study period (R² = 0.64-0.93), while exposure and adjusted vulnerability exhibited weaker, phase-dependent associations, becoming more prominent in the mid-2000s and after 2019. Four phases of FRI evolution of an initial surge (2000-2005) (0.000177), global escalation (2006-2010) (0.000614), transitional stabilisation (2011-2018) (-0.000156), and mild post-stabilisation decline (2019-2024) (-0.000064) reflect shifts in the underlying risk structure. Coupling results reveal that only SDG 1.5.2 (economic loss) and SDG 11.5.3 (infrastructure disruption) show significant negative associations with long-term FRI trends, while most SDGs display no significant relationship with flood risk at the global level. A similar pattern is observed in within-country analyses, where only a few nations show (positive or negative) significant SDG-FRI relationships, mainly under the former two and SDG 1.5.1, like Namibia, Indonesia, and Algeria, implying a structural misalignment between global SDG progress and actual flood-risk reduction. This finding highlights the need to recalibrate disaster-related SDG indicators to better reflect hazard intensification, exposure dynamics, and the evolving socio-institutional determinants of flood vulnerability.