From Extreme Areal Rainfall to Flood Risk Using a Derived Distribution Approach with Examples of Climate Change Impacts

Abstract

The aim of the report within GEMINA project is to present a methodology to probabilistically derive peak flood distribution from the statistical representation of extreme rainfall at the fixed durations of 1, 3, 6, 12, 24 hours over an area of interest. The methodology provides an analytical approach to derive the flood peak frequency distribution from the statistical characterisation of rainfall using a simplified description of the catchment response (SCS-CN model) to link rainfall and peak flood. The comparison between empirical and derived peak flood distribution evidences that the model performances have to be improved inserting a scaling factor dependent on the return period. The methodology is applied to the Baganza river basin in Emilia Romagna region (North Italy). Furthermore the methodology is used to investigate the effects of a positive and a negative variation of the average rainfall on peak flood distribution. Future applications will be based on climate and rivers discharge generated within the GEMINA project.