A STUDY ON THE PERFORMANCE EVALUATION OF RAINFALLRUNOFF REDUCTION FACILITIES IN URBAN WATERSHEDS

Due to climate change and the increase in impervious areas, the frequency and scale of flood damage in urban catchments are increasing. Consequently, the design and implementation of rainfall runoff reduction facilities have gained critical importance. This study evaluates the performance of four types of Low Impact Development (LID) facilities to minimize flood damage in Youngsan River basin, Republic of Korea. Storm Water Management Model (SWMM) was employed to model LID application strategies, and design parameters of LID facilities were optimized for each sub-catchment to evaluate their runoff reduction performance. The analysis results indicate that both Bio-retention Cells and Rain Gardens show outstanding performance, with Bio-retention Cells demonstrating the highest runoff reduction effectiveness. Furthermore, the analysis of LID facilities distribution across sub-catchments revealed a diverse selection of optimal facility types. Among the 21 target sub-catchments, BRC was the most frequently selected facility, followed by PP, RG, and IT. In areas where storage capacity is critical, storage-type facilities (BRC, RG, PP) were preferred over IT, which provides only infiltration. These findings highlight the importance of considering sub-catchment runoff characteristics when designing LID facilities to maximize runoff reduction efficiency. Through a comparison with actual flooded regions, the most effective LID facility types were selected to provide insights into urban flood management.