A technical note on the influence of time-series length on the intensity-duration-frequency curves for Lazio Region

A proper study of high intensity precipitation allows a reduction of the uncertainty in the estimation of the return period of the extreme rainfall, useful for hydraulic works design and for the management of hydrological risk. Because of the intrinsic uncertainty of the rainfall phenomena, it is necessary to adopt a probabilistic approach based on the definition of a theoretical probability distribution that can adequately describes observed data. Nevertheless, a recurring problem, concerns the presence of missing values and the discontinuity of the rainfall recorded data. Therefore, it is important to evaluate when an empirical sample can be considered reliable for an objective estimation of the return period associated to an extreme event. In this paper we used observation of annual maxima rainfall to investigate the changes in the intensity-duration-frequency (IDF) curves when varying the considered registration period length. Short duration and high intensity rainfall data recorded by eight rain gauges in Lazio region (central Italy) for the period between 1928 to 2017 are available.