Enhancing Road Drainage Systems for Extreme Storms:Integration of a High-Precision Flow Diversion Module into SWMM Code

Urban road networks function as surface passage for floodwater transport during extreme storm events to reduce potential risks in the city.However,precise estimation of these flow rates presents a significant challenge.This difficulty primarily stems from the intricate three-dimensional flow fields at road intersections,which the traditional one-dimensional models,such as Storm Water Management Model(SWMM),fail to precisely capture.The two-dimensional and three-dimensional hydraulic models are overly complex and computationally intensive and thus not particularly efficient.This study addresses these issues by integrating a semiempirical flow diversion formula into the SWMM source code.The semiempirical formula,derived from hydraulic experiments and computational fluid dynamics simulations,captures the flow dynamics at T-shaped intersections.The modified SWMM's performance was evaluated against experimental data,and the original SWMM,the two-dimensional MIKE21,and the three-dimensional FLUENT models.The results indicate that the modified SWMM matches the precision of the two-dimensional MIKE21,while significantly reducing computational time.Compared to MIKE21,this study achieved a Nash-Sutcliffe efficiency of 0.9729 and a root mean square error of 0.042,with computational time reduced by 99%.The modified SWMM is suitable for real-sized urban road networks.It provides a high-precision tool for urban road drainage system computation that is crucial for effective stormwater management.

From risk control to resilience: developments and trends of urban roads designed as surface flood passages to cope with extreme storms

Urban roads can be designated as surface flood passages to transport excess runoff during extreme storms, thereby preventing local flooding, which is known as the major drainage system. However, this practice poses significant risks, including human loss and property damage, due to the high flow rate and velocity carried by roads. Moreover, urban roads with low flood-resilience may significantly hamper the transportation function during severe storms, leading to dysfunction of the city. Therefore, there is an urgent need to transform risk-oriented flood passages into resilient urban road-based flood passages. This paper presents a systematic review of existing methodologies in designing a road network-based flood passage system, along with the discussion of new technologies to enhance system resilience. The study also addresses current knowledge gaps and future directions. The results indicate that flood management measures based on the urban road network should integrate accessibility assessment, lifeline and emergency planning to ensure human well-being outcomes. Furthermore, the special needs and features of vulnerable groups must be taken into serious consideration during the planning stage. In addition, a data-driven approach is recommended to facilitate real-time management and evaluate future works.