A Case Study on Simulation of Urban Inundation by Inland Flooding and River Flooding

Urban flooding can occur due to a combination of factors such as insufficient drainage capacity in stormwater systems, inland flooding from elevated river levels, and river flooding. This study proposes a method for analyzing urban inundation resulting from these complex phenomena using XP-SWMM. This is essentially a model capable of calculating the flow of drainage systems in urban watersheds and analyzing surface inundation. Moreover, it can accommodate irregular channel cross-sections and bridges, enabling river flooding modeling. However, it has limitations in terms of replicating the actual flooding patterns of rivers due to its representation of rivers through one-dimensional links and nodes. This study implemented virtual control structures to reflect the flooding effects caused by river flooding. This approach was applied to the Dongcheon watershed in Busan, where two instances of river and inland flooding coincided in July 2020. The results indicated the appropriateness of the approach.