Analysis of Urban Flood Characteristics under Variations in Storm Temporal Patterns

Because urban flood characteristics are governed not only by total rainfall amount but also by its temporal distribution, this study applied the HSD (Heavy Storm Distribution) method incorporating the Truncated Laplace distribution. Various rainfall temporal patterns—including both unimodal and bimodal distributions—were implemented for the study area to analyze the resulting urban inundation characteristics. For unimodal rainfall events, the overflow volume produced using the HSD-based temporal distribution was approximately 51% greater than that obtained using the conventional Huff method. For bimodal events, the reduced temporal concentration of rainfall led to an overall decrease in overflow volume compared with unimodal events; however, depending on the specific configuration of the bimodal pattern, overflow decreased by up to 32%, with an average reduction of approximately 13%. The overflow results, which reflected diverse temporal rainfall distribution characteristics depending on the location and relative magnitude of the peaks, demonstrated that analyses of urban inundation must incorporate the effects of multiple temporal rainfall patterns. These findings also indicated the necessity of flood-mitigation planning that accounts for variability in temporal rainfall distribution.