Precipitation change in Italy: effects on design and management of stormwater quantity and quality control systems

This paper presents the first results of a broad-based study of precipitation behaviour in Italy and focuses on the possible consequences of precipitation change on urban stormwater management. Analyses of the yearly, seasonal and daily precipitation over the last few centuries have been carried out at various stations throughout Italy (Domodossola, Turin, Milan, Genoa, Mantua and Palermo). The study includes the analysis of annual maximum rainfall of different durations (1, 3, 6, 12 and 24 hours) over a period of about fifty years for nine stations (Domodossola, Turin, Mantua, Voghera, Bologna, Florence, Livorno, Naples, Palermo). For the complete series of annual maximum rainfall of different durations and for the partial series obtained by dividing each series into two sets of equal duration, depth duration values with return periods of 2, 5, 10 and 20 years have been calculated and interpolated with monomial equations commonly adopted in Italy. This study investigates potential tendencies both in the available daily precipitation series and in series of annual maximum rainfall of durations between 1 and 24 hours also using the non-parametric Mann-Kendal test. After this study of precipitation behaviour the paper focuses on the possible effects on the design and management of adequate and properly functioning stormwater drainage systems, flow control systems and stormwater quality control measures.