Core infrastructure systems like water, electricity, transport, and communication are fundamental to modern cities, supporting vital services and everyday societal operations. However, their resilience is increasingly threatened by the occurrence and severity of compound hazards, such as floods that occurs concurrently with power system outages. These risks increase systemic risks that go far beyond the original source of disruption and frequently cause cascade failures throughout interconnected networks. With an emphasis on the dynamics of interdependencies and cascading consequences, this study investigates the resilience of urban lifeline networks under compound hazard situations. To capture the multi-layered vulnerabilities of lifeline systems, the study combines functional dependencies, performance indicators, and hazard scenarios using a network-based modelling technique. The results demonstrate how interruptions in one industry may quickly spread to others, worsening service outages and impairing emergency response capabilities. Key resilience measures—robustness, redundancy, and recovery time—are evaluated to identify vulnerable nodes and routes under compound hazards. The paper also explores mitigation strategies such as advanced monitoring, decentralized energy systems, and adaptive infrastructure design. By linking hazard modelling with resilience assessment, the study advances knowledge and offers practical insights for policymakers and engineers to strengthen urban lifeline resilience. This review uniquely synthesizes recent advances in understanding the interdependencies and cascading dynamics of urban lifeline systems exposed to compound hazards. It provides a comprehensive framework that integrates systemic risk concepts with resilience assessment approaches, offering new insights for urban resilience research and practice. This review contributes to the current body of knowledge by synthesizing existing research on cascading failures and systemic risks affecting urban lifeline systems under compound hazards, and by proposing a conceptual framework to enhance urban resilience planning and risk-informed decision-making.

In this study, the flow characteristics around a group of three piers arranged in tandem were investigated both numerically and experimentally. The simulation utilised the volume of fluid (VOF) model in conjunction with the k–ɛ method (i.e., for flow turbulence representations), implemented through the ANSYS FLUENT software, to model the free-surface flow. The simulation results were validated against laboratory measurements obtained using an acoustic Doppler velocimeter. The comparative analysis revealed discrepancies between the simulated and measured maximum velocities within the investigated flow field. However, the numerical results demonstrated a distinct vortex-induced flow pattern following the first pier and throughout the vicinity of the entire pier group, which aligned reasonably well with experimental data. In the heavily narrowed spaces between the piers, simulated velocity profiles were overestimated in the free-surface region and underestimated in the areas near the bed to the mid-stream when compared to measurements. These discrepancies diminished away from the regions with intense vortices, indicating that the employed model was capable of simulating relatively less disturbed flow turbulence. Furthermore, velocity results from both simulations and measurements were compared based on velocity distributions at three different depth ratios (0.15, 0.40, and 0.62) to assess vortex characteristic around the piers. This comparison revealed consistent results between experimental and simulated data. This research contributes to a deeper understanding of flow dynamics around complex interactive pier systems, which is critical for designing stable and sustainable hydraulic structures. Furthermore, the insights gained from this study provide valuable information for engineers aiming to develop effective strategies for controlling scour and minimizing destructive vortex effects, thereby guiding the design and maintenance of sustainable infrastructure.