New challenges and opportunities in pluvial flooding modelling: the Genoa case study

This research focuses on the detailed investigation of input data used in the modelling of pluvial flood events. Among the various input data—precipitation, urban drainage system characteristics, and terrain description—this work places specific emphasis on the topographic input, which plays a crucial role in determining overland flow dynamics and flood extent. A comprehensive review of the existing literature [1] revealed that terrain data, despite its significant influence on hydrodynamic results, has often been selected empirically or based on data availability, without a systematic assessment of its sensitivity and impact on model performance. This research seeks to fill that gap by proposing a structured approach to evaluate how different types and resolutions of topographic data affect the accuracy and reliability of pluvial flood simulations. Methodology The study employs open-source modelling tools, with the primary analyses conducted using the IBER [2] software for two-dimensional (2D) surface flow simulations. Detailed experiments were carried out to compare simulation outcomes obtained from multiple-resolution digital terrain models (DTMs). The approach involved: • Evaluating the resulting variations in water depth, flow velocity, and inundation extent; • Qualitatively analysing the potential errors and uncertainties arising from the selection of topographic input data. The analysis allowed for an in-depth understanding of the relationship between terrain data characteristics and model response, providing a first step toward defining guidelines for optimal data selection. Main Findings and Future Work Preliminary results indicate that the accuracy and spatial resolution of topographic data significantly influence the simulated flood dynamics. Coarser or poorly processed terrain inputs can lead to substantial deviations in flow paths and water depth estimations, potentially resulting in misinterpretations of flood risk and vulnerability. Future developments will extend the current work by implementing a 1D–2D coupled modelling approach, integrating IBER with SWMM (Storm Water Management Model). This coupling will allow for the combined analysis of surface runoff and drainage system behaviour, providing a more comprehensive understanding of urban flood processes and improving predictive capability. Contribution to the State of the Art This research contributes to the advancement of knowledge in urban flood modelling by systematically assessing the role of terrain input data—an aspect often overlooked in existing studies.