Assessing flood risk to urban road users based on rainfall scenario simulations

This study establishes a standard risk assessment method to quantify flood risks to urban road users based on rainfall scenario simulations, considering the occurrence probability of different magnitudes of rainfalls and economic consequences. An Analytic Hierarchy Process (AHP) is conducted to develop a risk assessment index system, determining the relative severity of different hazardous events. This study adopts the Storm Water Management Model (SWMM) to estimate road user delay and associated costs under simulated rainfall scenarios by the Synthetic Storm Pattern Generator (SSPG). A case study showed that flash flooding incurs over 2.89 million United States dollars/km risks to road users in 20 years. Retrofitting the impervious catchments with permeable pavements was found to reduce risks by 77 % and the drainage pipe diameter affects flood duration most. The proposed method can be used to evaluate flash flood risks to users for any road and to develop efficient risk treatment measures.