1 - Introduction
As discussed by Pirazzoli and Tomasin (2007), most methods usually employed to estimate return periods of extreme values for hydrological or meteorological datasets (extremes per block, threshold method, annual maxima (Gumbel)) are based on a number of assumptions that are generally poorly satisfied by most tide-gauge records. To overcome these difficulties, Pugh and Vassie (1979) introduced the joint probabilities method (JPM), which involves empirical evaluation of the probability of tide and surges separately, assuming independence between the two processes. With this technique, estimates can be made even from a few years of data, because the hourly surge component can be used as a continuous record that occurs during the period considered, thus extending the statistics. With this technique an incomplete series of data can also be used, if missing data do not correspond systematically to the same periods of the year.
However, it has been shown (Pirazzoli and Tomasin (...)