Differential orographic impact on sub-hourly, hourly, and daily extreme precipitation
Authors:Formetta, Giuseppe Marra, Francesco Dallan, Eleonora Zaramella, Mattia Borga, Marco
Volume:159
DOI:10.1016/j.advwatres.2021.104085
Published:2022
Document Type:Article
Abstract:Extreme precipitation of multiple durations is responsible for major natural hazards in mountainous regions, such as flash floods and debris flows. Understanding the orographic impact on the statistics of precipitation extremes is therefore crucial for improving hydrological design and risk management strategies. Here, we use a novel statistical approach for the analysis of extremes based on ordinary events to improve our understanding of the omgraphic impact on extreme precipitation of durations ranging between 5 min and 24 h. We focus on Trentino, a rough omgraphic region in the eastern Italia Alps, and use data from 78 quality-controlled rain gauges with 5-minute resolution. We show that our framework well reproduces the statistical properties of the observed annual maxima (Nash-Sutcliffe 0.82-0.95, Bias from -4% to 7%) as well as their relation with orography. We then exploit the reduced uncertainty of this approach to quantify the omgraphic impact on precipitation right-tail statistics and on extreme return levels using a regression analysis. We identify two main modes of orographic relationship: a reverse orographic effect for hourly and sub-hourly durations (10-20% decrease per 1000 m elevation) and an orographic enhancement for durations of similar to 8 h or longer (7.5-10% increase per 1000 m elevation). We observe that these two modes result from three main precipitation regimes, which show different proportion between extreme and very-extreme events and which emerge at very short durations (similar to 20 min or shorter), mid durations (similar to 30 min-1 hour) and long durations (similar to 2 h or longer). These findings are of interest for risk management applications and climate change impact studies.
Author Information
Corresponding Author:Formetta, G (通讯作者)，Univ Trento, Dept Civil Environm & Mech Engn, Trento, Italy.
Reprint Address:Formetta, G (通讯作者)，Univ Trento, Dept Civil Environm & Mech Engn, Trento, Italy.
Addresses:[Formetta, Giuseppe] Univ Trento, Dept Civil Environm & Mech Engn, Trento, Italy; [Marra, Francesco] Natl Res Council Italy, Inst Atmospher Sci & Climate CNR ISAC, Bologna, Italy; [Dallan, Eleonora; Zaramella, Mattia; Borga, Marco] Univ Padua, Dept Land Environm Agr & Forestry, Padua, Italy
E-mail Addresses:giuseppe.formetta@unitn.it