Assessment on vulnerability of road networks considering the dynamic impact of urban waterlogging and the mitigation effect of LID measures

The urban waterlogging stemming from the rainstorm exerts a considerable adverse influence on road networks. Accurately evaluating the vulnerability of road networks during waterlogging is a crucial measure to alleviate flood risk and damage. Nevertheless, previous research merely considered the maximum inundation depth of waterlogging, but neglecting the dynamic variation of waterlogging. In this study, we firstly develop a coupled hydrodynamic model (IFMS-Urban + SWMM) and integrated it with a road traffic model to analyze the impact of waterlogging on road networks; then, a time factor is involved to assess the dynamic variation of flood vulnerability by using a novel index road vulnerability recovery index (RVRI); finally, the mitigatory effect of low impact development infrastructure/practices (LIDs) on the vulnerability of transportation roads under waterlogging was investigated. The results show that, both the coupled hydrodynamic model and road traffic model were verified for logical soundness and show strong adaptability. The urban waterlogging becomes increasingly severe with the increase of return period of rainstorms and leads to a corresponding rise in the vulnerability of the road network. The evaluation system of road network vulnerability becomes more comprehensive and reasonable with the consideration of the time factor. The well-arranged LIDs can effectively reduce the vulnerability of road network. This study serves as a valuable reference for dynamically assessing the vulnerability of road networks to urban waterlogging, offering guidance for urban waterlogging prevention, road traffic management, and road operation and maintenance in urbanized areas.