Author(s): Shubing Dai; Esteban Sanudo; Luis Cea; Shuai Wang; Jeronimo Puertasd

Linked Author(s): Luis Cea Gómez, Shubing dai, Esteban Sañudo Costoya

Keywords: Dual drainage model; Grate inlets; Uncertainty quantification; Urban flooding; Iber-SWMM

Abstract: Grate inlets play a critical role in the interaction between surface runoff and sewer flow, yet their influence on urban flood dynamics remains underexplored in most 1D-2D dual-drainage models. This study quantifies the uncertainty associated with grate inlet parameters—distribution density, weir discharge coefficient, and area—using a coupled Iber-SWMM model. The model was calibrated and validated with field data from a 1.5 km² urban catchment under three rainfall events. Results show that increasing distribution density, discharge coefficient, or inlet area reduces surface inundation extent and maximum water depth, while increasing peak discharge and hydraulic head in the sewer network and advancing their timing. Among these, inlet area has the least influence. Compound effects of multiple parameters reveal that minimal values lead to severe surface flooding and delayed pipe network response. Spatial heterogeneity analysis indicates that stronger drainage measures upstream mitigate downstream flooding more effectively than localized downstream improvements. These findings underscore the importance of grate inlet representation in urban flood modelling and provide guidance for improved drainage system design.

DOI:

Year: 2026