High-resolution analysis of 1-day extreme precipitation in a wet area centered over eastern Liguria, Italy

Abstract

This study analyses 371 yearly series of 1-day precipitation maxima extracted from a data set of highquality homogenized rain gauge records covering an area of about 25000 km 2 in the western part of northern-central Italy that includes eastern Liguria and northern Tuscany and is very prone to severe floods and shallow landslides. Return levels of 1-day extreme precipitation (corresponding to 10-, 50-and 100-year return periods as predicted by a generalized extreme value distribution (GEV)) are estimated both for station sites and for the nodes of a high-resolution grid (30 arcsec). GEV parameters are estimated by regional frequency analysis using the station-year approach. Grid point index floods are estimated from yearly cumulative precipitation normals exploiting the very high correlation existing at local scale between station index flood and the corresponding yearly precipitation normals. Results clearly show the high vulnerability of this region to extreme precipitation events and highlight the different role played by total annual precipitation normals and by both scale and shape parameters in regulating the longer period return levels. The results presented in this paper allow better estimating the climatology of extreme events in the study area, contributing to a more effective hazard assessment at different spatial and temporal scales.

Daily precipitation variability in the southern Alps since the late 19th century

“…Our analysis of heavy precipitation events extends the results of Scherrer et al () out of the Swiss borders and show that the behaviour of annual precipitation maxima in the southern Alps is more complex than in Switzerland (where an increase is observed everywhere). In particular, there is no detectable increase of annual indices of heavy precipitation events in the south‐eastern Alps, similar to what is found for other regions in Northern Italy (e.g., Brunetti et al, ). The prevalent climatological occurrence of extreme events (late summer/early autumn in the west, late autumn in the east) is arguably one of the factors driving these differences.…”

“…In the Mediterranean basin (which includes the southern Alps), however, signals in extremes are less spatially coherent (Ulbrich et al, ). For instance, no significant trends are observed in the northwestern Apennines (Brunetti et al, ), a region with strong climatic similarities to the southern Alps (Brunetti et al, ).…”

Hillslope degradation in representative Italian areas: Just soil erosion risk or opportunity for development?

“…On average, because of the combined effect of the humidifying action of the sea and the chain effect, the coastal sectors receive somewhat abundant rainfall annually (mean annual value of about 1,040 mm referred to the Levanto rain gauge station and considering a period of 62 years between 1954 and 2016), mainly concentrated in autumn and winter (Figure a; Cevasco et al, ). It is worth to note that heavy and very concentrated rainfall can affect this area during the autumn season, as dramatically evidenced by the October 25, 2011, rainstorm event (Brunetti et al, ; Cevasco et al, ; Galanti, Barsanti, Cevasco, D'Amato Avanzi, & Giannecchini, ).…”

“…Due to land abandonment and land reclamation, hilly and mountainous landscapes have been subject to widespread degradation (García‐Ruiz & Lana‐Renault, ). Slope degradation, together with new scenarios of climate change, has an essential role in increasing erosion and landslide susceptibility (Brunetti, Bertolini, Soldati, & Maugeri, ; Capolongo, Diodato, Mannaerts, Piccarreta, & Strobl, ; Cevasco et al, ; Glade, ; Galve, Cevasco, Brandolini, & Soldati, ; Lesschen, Cammeraat, & Nieman, ; Piccarreta, et al, ; Vergari, Della Seta, Del Monte, Fredi, & Lupia Palmieri, ). Where peculiar geologic (e.g., environments characterized by erodible terrains) and climatic settings exist, slope degradation can favour the development of badlands (Capelli, Miccadei, & Raffi, ; Phillips, ; Clarke & Rendell, ; Faulkner, Alexander, & Wilson, ; Farifteh & Soeters, ; Nadal‐Romero, Latron, Lana‐Renault, Serrano‐Muela, & Regüés, ; Vergari, Della Seta, Del Monte, Fredi, & Lupia Palmieri, ; Vergari, ).…”

Bridging Terrestrial and Marine Geoheritage: Assessing Geosites in Portofino Natural Park (Italy)

“…The meteo-climatic characteristics of this area are linked to the cyclogenesis of the Gulf of Genoa, which causes events of short but intense precipitation (less than 6 h, with rain peaks exceeding 50 mm/h) between mid-summer and mid-autumn [93,102,103]. Consequently, the most common effects at ground level are flash floods, hyper-concentrated fluxes, and debris/mud flows.…”