Calibration of stormwater management model using flood extent data

The Seogu (western) portion of Daegu, Korea experiences chronic urban flooding and there is a need to increase flood detention and storage to reduce flood impacts. Since the site is densely developed, use of an underground car park as a cistern has been proposed. The stormwater management model (SWMM) is applied to study alternative hydraulic designs and overall performance, and it is shown that by linking SWMM to a two-dimensional flood inundation model, SWMM parameters can be calibrated from observations of flood extent. Calibration would otherwise not be possible because storm sewer flows are not internally monitored. This study reveals a significant sensitivity in SWMM relative to surcharge prediction, demonstrates a creative repurposing of urban infrastructure to manage extreme flood events and shows the importance of flood documentation relative to drainage infrastructure analysis and design.