Orographic Effects on Extreme Rainfall at Different Durations: A Case Study in Campania Region (Southern Italy)

Long-term probabilistic prediction of extreme rainfall at the regional scale is a significant tool in the mitigation of hydro-geological disasters: it actually provides the starting point in the design of strategic hydraulic infrastructures and emergency plans. A crucial task of regional estimation of extreme rainfall is how to include the complex effects of orographic barriers in a mathematical model for Intensity-Duration-Frequency (IDF) curves. Here, an analysis of how orography can affect extreme rainfall at different durations is presented for three orographic systems that are very relevant for hydrological risk assessment in the Campania Region in Southern Italy. Then, we introduce a power law model to link the amplification factor to the duration, thus allowing a simple and effective enhancement of the IDF model in mountainous areas.