At-site and regional assessment of the possible presence of non-stationarity in extreme rainfall in northern Italy

The possible presence of non-stationarity in long rainfall records, along w ith the related consequences in the estimation of the frequency distributio n of the extreme events, was recently pointed out in several scientific stu dies. However, it is well known that the detection of the presence of non-s tationarity may be affected by relevant uncertainties, which are mainly ori ginated by the limited length of the available data samples. The present pa per describes an analysis aimed at detecting the possible presence of non-s tationarity in some long rainfall records observed in northern-central Ital y. Firstly a regional analysis is performed in order to assess the possible presence of non-stationarity at regional scale. Secondly synthetic rainfal l series are analysed in order to assess how much the sample variability of a short stationary series might induce effects which could be attributed t o non-stationarity. (C) 2001 Elsevier Science Ltd. All rights reserved.