Analysis of the Sanchung inundation during Typhoon Aere, 2004

Typhoon Aere swept over Taiwan with heavy rain, which induced huge discharge in the Danshuei River in August 2004. The flood in the Danshuei River intruded Sanchung through a culvert that was under construction. The deluge inundated thousands of premises and resulted in severe damage. This study reconstructs the event scenario using hydrologic and hydraulic methods to analyse the causes of the disaster. We integrated the radar rainfall estimations and rain gauge observations to recreate the temporal and spatial varied precipitation inputs; estimated the influent volume from the culvert using hydrologic equations; and simulated the flood dynamic within the study area during the event with a coupled overland and sewer flow model. The evidence showed that both the rainfall and the culvert flow contributed similar flood volume to the study area, but culvert discharge concentrated at single location within short time period such that the local drainage system could not cope with and notable damage was incurred.