On the feasibility of thresholds for the classification of daily precipitation in Lazio region

Daily rainfall series analysis is crucial both for engineering design purposes, freshwater management and it currently used in various types of agriculture management models to evaluate the associated drought risk. More recently the studies of daily rainfall events are used to investigate changes in rainfall occurrence. A basic approach to accomplish this aim is to identify the magnitude of the events and regroup them into categories. Some studies in literature proposed a classification of daily rainfall events based on single thresholds, which are commonly defined for quite large areas. Because the location and seasonality are recognized to be influencing factors for particular precipitation regime, the reliability of classification methods based on single thresholds should be properly assessed for the different locations and time scales. In this paper an investigation on the applicability of single thresholds for daily rainfall events classification for Lazio region is presented. For the case study, results suggest that a classification based on single thresholds is not suitable and therefore the need for a different approach is required.