title: Storminess and geo-hydrological events affecting small coastal basins in a terraced Mediterranean environment.
abstract: This study was prompted by the occurrence of an extreme Damaging geo-Hydrological Event (DHE) which occurred on October 25th 2011 and which affected a wide area of the northern Mediterranean region. After analysing the storm by means of the precipitation time series, the study attempts to relate the October 25th 2011 DHE with a series of other DHEs that occurred in the period 1954-2012, assessed via the use of historical data and classified according to severity, with a Storm Erosivity Indicator (Ra). The annual mean of the Ra value (2582 MJ mm ha(-1) h(-1) y(-1)) confirmed that the study area is one of the European regions with the highest rainfall erosivity level. A shift in storminess during 1991-2012 with respect to 1954-1990 was observed. A return period of 1000 years was calculated for the single storm erosivity of October 25th, which contributed to 84% of the total annual storm erosivity of 2011 A quite good agreement was found comparing DHE distribution and severity with Ra anomalies over time. As a matter of fact, most of the low severity DHEs (62.5%) occurred in years in which the Ra was below the average value. Moreover, almost all DHEs (93%) ranging from medium- to very high-severity occurred in years for which the Ra exceeded the average value. With regard to the occurrence of the most severe DHE classes, a threshold of the Ra and a recurrence time of approximately 3300 MJ mm ha(-1) h(-1) y(-1) and 12 years, respectively, were identified. Finally, some evidences suggest that an increasing frequency of DHEs is expected in the forthcoming years. It is argued that understanding these issues is a major priority for future research in order to improve land and urban planning strategies for preserving people and the environment, leading ultimately to an effective risk reduction.
authors.affiliation: Department of Earth, Environment and Life Sciences, University of Genova, Corso Europa, 26, 16132 Genova, Italy. Electronic address: cevasco@dipteris.unige.it.
authors.forename: Andrea
authors.initials: A
authors.lastname: Cevasco
authors.affiliation: Department of Science and Technology, University of Sannio, 82100 Benevento, Italy; Met European Research Observatory, 82100 Benevento, Italy.
authors.forename: Nazzareno
authors.initials: N
authors.lastname: Diodato
authors.affiliation: Department of Science and Technology, University of Sannio, 82100 Benevento, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Revellino
authors.affiliation: Department of Science and Technology, University of Sannio, 82100 Benevento, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Fiorillo
authors.affiliation: Department of Science and Technology, University of Sannio, 82100 Benevento, Italy.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Grelle
authors.affiliation: Department of Science and Technology, University of Sannio, 82100 Benevento, Italy.
authors.forename: Francesco M
authors.initials: FM
authors.lastname: Guadagno
keywords: Climate change impacts; Extreme precipitation events; Geo-hydrological hazard; Land-use planning; Rainfall intensity; Storm erosivity