Exploring the robustness of the Synthetic Flood Attenuation Index for large-scale flood hazard assessment

Dams can modify the propagation of flood hydrographs by naturally dampening flood peaks. However, this effect is often overlooked when assessing flood frequency curves, leading to potential inaccuracies in estimating flood hazard downstream, particularly in areas where a large number of reservoirs exist. This work focuses on a preliminary robustness assessment of the Synthetic Flood Attenuation (SFA) index, which incorporates key factors influencing flood mitigation effectiveness of artificial reservoirs. We update results for a sample of dams in Northwestern Italy from a previous study and compare the SFA index's classification of flood attenuation potentials with a national-scale analysis we recently performed. This comparison aims to understand the suitability of the SFA index across various reservoir-territory combinations, given its assumptions of no spatial rainfall variability and standardized morphology. Our findings suggest the SFA index appears to be a reliable tool for a preliminary assessment of flood attenuation potentials at a national scale in Italy, even if further studies are needed to clarify its range of applicability. This analysis provides a basis for further development and application of the SFA index to support sustainable flood risk management strategies.