Search results for "Debris flow"
showing 10 items of 33 documents
La Franosità diffusa dell'1 Ottobre 2009 nel territorio ionico-peloritano della Provincia di Messina: stato delle indagini e prime considerazioni sul…
2009
A seguito di un evento estremo di pioggia verificatosi il 1 ottobre 2009 in un settore circoscritto del versante ionico della Provincia di Messina, si sono sviluppati numerosi eventi franosi classificabili per la maggior parte come colate di fango e detrito a rapida evoluzione (debris-mud flows). Dai primi sopralluoghi effettuati, in assenza ancora di un censimento sistematico, si sono riconosciuti eventi in numero di oltre 500, che hanno interessato sia nei versanti interni dei bacini idrografici che sversano nello Ionio, sia sui rilievi direttamente prospicienti la costa. L’elevato numero di eventi occorsi ha consentito di dettagliare dal punto di vista morfologico i fenomeni avvenuti e d…
A test of transferability for landslides susceptibility models under extreme climatic events: application to the Messina 2009 disaster
2014
A model building strategy is tested to assess the susceptibility for extreme climatic events driven shallow landslides. In fact, extreme climatic inputs such as storms typically are very local phenomena in the Mediterranean areas, so that with the exception of recently stricken areas, the landslide inventories which are required to train any stochastic model are actually unavailable. A solution is here proposed, consisting in training a susceptibility model in a source catchment, which was implemented by applying the binary logistic regression technique, and exporting its predicting function (selected predictors regressed coefficients) in a target catchment to predict its landslide distribu…
Hyperconcentrated flow and men velocity estimation: a study case
2015
Due to the complexity of the debris-flow process, numerical models to simulate propagation phenomenon are still limited. Different approaches (either monophase or two-phase) have been proposed in literature to solve the set of governing equations. But, the difficulty is due to the fact that these equations require suitable closure relations that should be valid in a very wide range of slope and materials characteristics. The point is that, in order to perform a hazard assessment and/or to design protective measures against debris flows, it is necessary to estimate important parameters such as mean flow velocity, peak discharge and runout distance. Experimental program has been recently cond…
Stage–Discharge Relationship for an Upstream Inclined Grid with Transversal Bars
2016
AbstractCheck dams with grids upgrading upstream are often used in mountain rivers, where intense sediment transport and steep slopes occur. In some cases, sloping grids are used in the construction of debris flow breakers. In this paper, the outflow process of an upstream-inclined grid with transversal bars is studied by using the dimensional analysis and the incomplete self-similarity theory. Next, the theoretical analysis shows that a power equation can be used for establishing the stage-discharge equation. The coefficient of the power equation depends on both the slope angle and the void ratio, whereas the exponent depends only on the slope angle. Finally, this deduced stage–discharge r…
Mapping Susceptibility to Debris Flows Triggered by Tropical Storms: A Case Study of the San Vicente Volcano Area (El Salvador, CA)
2021
In this study, an inventory of storm-triggered debris flows performed in the area of the San Vicente volcano (El Salvador, CA) was used to calibrate predictive models and prepare a landslide susceptibility map. The storm event struck the area in November 2009 as the result of the simultaneous action of low-pressure system 96E and Hurricane Ida. Multivariate Adaptive Regression Splines (MARS) was employed to model the relationships between a set of environmental variables and the locations of the debris flows. Validation of the models was performed by splitting 100 random samples of event and non-event 10 m pixels into training and test subsets. The validation results revealed an excellent (…
Hydrogeological hazards and weather events: Triggering and evolution of shallow landslides
2014
Abstract Landslides are the most intense and serious manifestations of the degradation of slopes and they are the main causes of geological hazard when they, directly or indirectly, involving towns and infrastructures. They are a global environment problem; there are several examples that have produced untold damages and loss of human lives in many parts of the world. In 1920 the landslides mobilization, as a result of a strong earthquake in China, in the province of Kansu, killed 200,000 people; in 1938 fast debris flow, triggered by heavy rainfalls in Japan, caused the death of 600 people; in 1963 in Italy the Vajont disaster caused the death of 1,899 people, as a result of a landslide lo…
Estensione e ciclicità di accumuli debritici tardo-pleistocenici nei bacini di Sibari e Corigliano (Mar Ionio): implicazioni per la tettonica recente…
2013
Corpi sedimentari caratterizzati da facies sismica “trasparente” di notevole spessore (sino a 35 m) sono stati documentati in più livelli della copertura tardo-pleistocenica della Piana Abissale del Mar Ionio ed interpretati come megatorbiditi innescate da megatsunami. Il più recente di questi corpi è stato posto da Autori vari, in relazione ai collassi vulcanici del Santorini o dell’Etna o al sisma distruttivo di Creta del 365 d.C. [Polonia et al., 2013]. Corpi “trasparenti” di notevole spessore (15-30 m) e estensione (> di 100 km2), sono stati segnalati anche nel Mar Ionio nord-occidentale e interpretati come accumuli debritici tardo-pleistocenici-olocenici, presumibilmente sismoindotti […
Experimental Analysis of Velocity Distribution in a Coarse-Grained Debris Flow: A Modified Bagnold’s Equation
2020
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Flow characteristics of a channelized debris-flow and implications in numerical modelling: a study case
2012
As it is known, debris flows are characterized by extreme propagation rapidity and by the ability to move high quantity of fluid mass. Furthermore, debris flows are fluid enough to travel long distances and, thus, to cause damage in vast areas, even far from the trigger ones. Debris-flow runout estimations are important for the delineation of potentially hazardous areas. Especially in recent years, several researches have been conducted in order to define predicitive models. But, existing runout estimation methods need input parameters that can be difficult to estimate. Recent advances in theory and in experimental research have allowed the assessment of the physics of the debris flows. On …