Flood risk management systems have traditionally relied on hard-engineered measures to improve conveyance and local hydraulic capacity, while nature-based solutions that slow, store, or desynchronise flows are increasingly being promoted for their capabilities in adapting to changing climate conditions and wider environmental benefits. However, the comparative effectiveness of these approaches and the extent to which they can complement one another as an integrated approach remains to be explored further and better characterised. This study evaluates and compares hard-engineered, nature-based solutions (NbS), and their integration for flood risk management using a one-dimensional unsteady flow hydraulic model of the Bin Brook catchment in the UK, where recurrent property flooding is driven by an undersized culvert. Modelled results show that hard-engineered scenarios are most effective in lowering water surface elevations, whereas NbS produce greater delays in peak flow arrival times and desynchronise runoff from rural upstream sub-catchments. When combined, these approaches produce complementary effects and achieve greater flood risk reduction than either approach could accomplish alone.

The lifeline emergency and safety systems constitute the critical infrastructure networks that sustain our modern society. They play a key role in ensuring the smooth functioning of transportation, communication and other economic activities, as well as guaranteeing public safety and human well-being. The smoothed particle hydrodynamics (SPH) approach has emerged as a powerful mesh-free numerical modelling technique with wide-ranging applications, one of which relates to the simulation of natural disasters in the field of lifeline engineering. The present review paper provides a comprehensive introduction to the SPH fundamentals, its applications in the urban lifeline studies, and its specific role in dam-break-disaster simulations. Through a synthesis of theoretical principles and case studies, this paper aims to elucidate the effectiveness and challenges of employing SPH techniques in addressing some of the critical issues of lifeline infrastructure resilience and flood risk management.