Natural Hazards and Earth System Science www.nat-hazards-earth-syst-sci.net 1561-8633 1684-9981 10 2 2010 10.5194/nhess-10-371-2010 http://www.nat-hazards-earth-syst-sci.net/10/371/2010/ http://www.nat-hazards-earth-syst-sci.net/10/371/2010/nhess-10-371-2010.html http://www.nat-hazards-earth-syst-sci.net/10/371/2010/nhess-10-371-2010.pdf 371 377 2010-02-23 Quantitative comparison of radar QPE to rain gauges for the 26 September 2007 Venice Mestre flood A. M. Rossa arossa@arpa.veneto.it G. Cenzon M. Monai Centro Meteorologico di Teolo – DRST, ARPA Veneto, Via Marconi 55, 35037 Teolo (PD), Italy In this study consideration is given to the potential use of radar-derived quantitative precipitation estimates (QPE) as flash flood guidance in the context of the Italian Civil Protection flood risk management system. The interest in high precipitation intensities and accumulation motivated the case study of the 26 September 2007 event, in which a quasi-stationary mesoscale convective system brought within 3–6 h 40% of the mean annual precipitation to the wider Venice-Mestre area, i.e. 260 mm in Venice-Mestre and 325 mm in closeby Valle Averto. <br><br> Comparison of the radar-derived QPE in the area with the rain gauge network revealed a good correspondence for warm season rainfall, both for daily accumulations in the longterm (about 2 years) and hourly accumulations for the case under consideration. The long term average radar to gauge ratio is very close to 0 dB with an uncertainty of approximately &plusmn;3 dB, i.e. roughly a factor of two, slightly better for higher precipitation intensities. 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