Variazione del regime delle piogge e aumento dei fenomeni alluvionali nell'area metropolitana genovese (Italia)

The Genoa Metropolitan Area is historically affected by flash floods for the meteorological conditions and city’s geomorphologic arrangement. In the last years in GMA there is also an increase in flash floods due to man-made landforms and changes in rainfall regime. The research analyses the rain data collected over more than 100 years, registered by Genoa University (since 1833) and Chiavari (since 1877) stations. Furthermore, data recorded since 1932 at Isoverde and Diga Giacopiane stations allow to complete the analysis. The analysis was based on mean annual rainfall, rainy days and rainfall intensity. The annual rainfall does not show any trend, but the number of rainy days shows a negative one, statistically significant, in all selected rain gauges. As a consequence, the rate of daily rainfall shows a positive trend. The scenario above is confirmed by the analysis of maximum precipitation recorded by pluviographs for 1, 3, 6, 12 and 24 hours: all the analyzed values indicate an increase over time, which may be linked to the intensification of flood events in the recent decades.