A reliable and long dataset describing urban flood locations, volumes and depths would be an ideal prerequisite for assessing flood frequency distributions. However, data are often piecemeal and long-term hydraulic modelling is often adopted to estimate floods from historical rainfall series. Long-term modelling approaches are time- and resource-consuming, and synthetically designed rainfalls are often used to estimate flood frequencies. The present paper aims to assess the uncertainty of such an approach and for suggesting improvements in the definition of synthetic rainfall data for flooding frequency analysis. According to this aim, a multivariate statistical analysis based on a copula method was applied to rainfall features (total depth, duration and maximum intensity) to generate synthetic rainfalls that are more consistent with historical events. The procedure was applied to a real case study, and the results were compared with those obtained by simulating other typical synthetic rainfall events linked to intensity–duration–frequency (IDF) curves. The copula-based multi-variate analysis is more robust and adapts well to experimental flood locations even if it is more complex and time-consuming. This study demonstrates that statistical correlations amongst rainfall frequency, duration, volume and peak intensity can partially explain the weak reliability of flood-frequency analyses based on synthetic rainfall events.
Research Article|June 01 2011
Uncertainty evaluation of design rainfall for urban flood risk analysis
C. M. Fontanazza
1Dipartimento di Ingegneria Civile Ambientale e Aerospaziale, Università degli Studi di Palermo, viale delle Scienze, Edificio 8, 90128 Palermo, Italy
2Universitá Kore di Enna, Cittadella Universitaria, 94100 Enna, Italy
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G. La Loggia
Water Sci Technol (2011) 63 (11): 2641-2650.
C. M. Fontanazza, G. Freni, G. La Loggia, V. Notaro; Uncertainty evaluation of design rainfall for urban flood risk analysis. Water Sci Technol 1 June 2011; 63 (11): 2641–2650. doi: https://doi.org/10.2166/wst.2011.169
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