Analysis of Flood Damage Mitigation Effects Based on the Presence of a Rainwater-Retaining Facility Through Flood-Depth Distribution Analysis by Grid

In recent years, localized heavy rainfall due to climate change has caused increased flood damage in urban areas. To address this issue, efforts are being made to mitigate damage through the installation of a rainwater-retaining facility and improved sewer systems. Various methods have been proposed to analyze the flood mitigation effects of these measures, with commonly used approaches including the analysis of overflow volume, peak flood discharge, and flood maps. However, these methods have limited capacity to accurately assess the reduction in flood depth, which directly affects human safety and property. Additionally, the use of flood maps requires visual analysis, which makes it difficult to evaluate the reduction effects accurately. Therefore, this study proposes a new method for flood reduction using grid-based flood-depth distribution analysis. The maximum flood depth for each grid was determined using the XP-SWMM urban runoff model, and the number of grids for each 0.1-meter flood-depth interval was analyzed using a Python program. Consequently, under various rainfall scenarios and boundary conditions, the proposed analysis method enables a more quantitative assessment of flood mitigation effects by comparing the number of reduced flood-depth grids before and after the installation of the rainwater retention facility. This approach also allows for a more precise assessment of the reconstruction of flood-depth grids, which directly affects human safety and property.