in this study, we propose a contagion model as a simple and powerful mathematical approach for predicting the spatial spread and temporal evolution of the onset and recession of floodwaters in urban road networks. A network of urban roads resilient to flooding events is essential for the provision of public services and for emergency response. The spread of floodwaters in urban networks is a complex spatial-temporal phenomenon. this study presents a mathematical contagion model to describe the spatial-temporal spread and recession process of floodwaters in urban road networks. The evolution of floods within networks can be captured based on three macroscopic characteristicsflood propagation rate (β), flood incubation rate (α), and recovery rate (µ)-in a system of ordinary differential equations analogous to the Susceptible-Exposed-Infected-Recovered (SEIR) model. We integrated the flood contagion model with the network percolation process in which the probability of flooding of a road segment depends on the degree to which the nearby road segments are flooded. The application of the proposed model is verified using high-resolution historical data of road flooding in Harris County during Hurricane Harvey in 2017. The results show that the model can monitor and predict the fraction of flooded roads over time. Additionally, the proposed model can achieve 90% precision and recall for the spatial spread of the flooded roads at the majority of tested time intervals. The findings suggest that the proposed mathematical contagion model offers great potential to support emergency managers, public officials, citizens, first responders, and other decision-makers for flood forecast in road networks. Given the essential role transportation plays in emergency response, provision of essential services, and maintenance of economic well-being 1 , the resilience of urban road networks to natural hazards, especially flooding events, has received increasing attention 2, 3. Floodwaters in urban networks propagate over time and space, inducing a great deal of spatial-temporal uncertainty visa -vis protective actions, such as evacuation, and rapid emergency response 4. Developing effective prediction tools to forecast the characteristics of flooding events is critical to the enhancement of urban road network resilience 5. Multiple studies have explored the spatial-temporal properties of floods in urban networks, including impact evaluation of environmental stress 6-8 and cascading effects in road networks 9, 10. In particular, empirical studies adopting remote sensors 11 , hydraulic data 12 , or satellite images 13 have attempted to capture the properties of urban flooding. Temporal evolution of flood status is driven by the time-dependent profile of environmental stress, such as the duration of rainfall in hurricanes 12. This temporal information facilitates identification of the outbreak and inflection points for flooding in affected networks. Flooding also exhibits high spatial correlation 14 in which the co-located road segments are...