Field Surveys and Numerical Modeling of Pumiceous Debris Flows in Amalfi Coast (Italy)

Papa, Maria Nicolina; Sarno, Luca; Ciervo, Fabio; Barba, Salvatore; Fiorillo, Fausta; Limongiello, Marco

doi:10.13101/ijece.9.179

Cited by 2 publications

(8 citation statements)

References 23 publications

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“…Such a circumstance allowed for a reasonably precise estimation of the total volume of the deposit behind the gabion wall, obtained by the comparison of two digital terrain models (DTM), taken before (27/06/2013) and after (18/10/2013) the event. The DTM were obtained by the terrestrial laser scanner (TLS) survey, employing the instrument TOPCON GLS-1500, and exhibit a very high resolution (of order of ≈1 cm), made possible thanks to the almost complete absence of vegetation inside the gully [30]. By comparing the two DTM, the volume of deposit was estimated equal to 146 During the DF event, the nearest rain gauge, located in the town centre of Tramonti (few kilometers South from the site), recorded a cumulative rainfall of 60 mm in 4 h with a maximum intensity of about 50 mm/h.…”

Section: Study Areamentioning

confidence: 99%

“…1.0.4), which is capable of yielding a high-resolution DTM through an image-based 3D-modelling algorithm. For more details about the photo-modeling survey technique we refer the Reader to our previous work [30].…”

Section: Study Areamentioning

confidence: 99%

“…Analogous to that reported in [30], the input debris flow discharge at the upstream section, S1 (i.e., upper boundary condition) was assumed to be a one-surge triangular hydrograph. The volume of the hydrograph was set equal to the measured volume of deposit, 146 m 3 .…”

Section: Preliminary Analysis For the Choice Of The Resistance Law Anmentioning

confidence: 99%

“…The peak flow rate, set equal to 5.15 m 3 /s, was estimated by imposing the peak flow depth observed in the cross section S1 and assuming the occurrence of the hydraulic critical state. The time length of the hydrograph is 56.7 s. A sensitivity analysis on the peak flow depth, varied within its accuracy range (i.e., between 70 cm and 100 cm), was performed in [30]. It was found that the depths of deposit exhibit negligible variations in the investigated range of input hydrographs.…”

Section: Preliminary Analysis For the Choice Of The Resistance Law Anmentioning

confidence: 99%

“…The digital terrain model (DTM) of the debris fan, before and after the event, was surveyed by terrestrial laser scanner (TLS). Moreover, the entire topography up to the debris flow scars (i.e., the initiation zones) was obtained by photo-modeling analysis of digital pictures, taken by an aerial survey carried out through a drone, i.e., an unmanned aerial vehicle (UAV) [30]. Different possible dam-break scenarios are investigated for the numerical reconstruction of the DF event.…”

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Application of the 2D Depth-Averaged Model, FLATModel, to Pumiceous Debris Flows in the Amalfi Coast

Papa

Sarno

Vitiello

et al. 2018

Water

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Few studies about modelling pumice debris flows are available in literature. An integrated approach based on field surveys and numerical modelling is here proposed. A pumiceous debris flow, which occurred in the Amalfi Coast (Italy), is reconstructed by the numerical code, FLATModel, consisting of a two-dimensional shallow-water model written in curvilinear coordinates. The morphological evolution of the gully and of the alluvial fan was monitored by terrestrial laser scanner and photo-modelling aerial surveys, providing, in a cost-effective way, data otherwise unavailable, for the implementation, calibration and validation of the model. The most suitable resistance law is identified to be the Voellmy model, which is found capable of correctly describing the friction-collisional resistance mechanisms of pumiceous debris flows. The initial conditions of the numerical simulations are assumed to be of dam-break type: i.e., they are given by the sudden release of masses of pumice, whose shape and depths are obtained by reconstruction of the pre-event slopes. The predicted depths and shape of deposits are compared with the measured ones, where a good agreement (average error smaller than 10 cm) is observed for several dam-break scenarios. The proposed cost-effective integrated approach can be straightforwardly employed for the description of other debris flows of the same kind and for better designing risk mitigation measures.2 of 22 meaning that the computational domain is large and, hence, the choice of the mesh size is crucial. From a practical viewpoint this typically involves vertical integration and averaging of the hydraulic variables, leading to models of the shallow-water type [23][24][25][26].Moreover, the evaluation of the energy losses during the flow has to be suitably addressed. Generally speaking, a debris flow is made up of a heterogeneous mixture of solids and liquids. In nature, the fluid is water or a slurry of water and fine sediments (clay and silt), and the solid phase is represented by natural grain soils, with a size ranging from silt to boulders. The physics governing the mixture behaviour at the micro-scale is fully defined by the classical equations of mechanics, taking into account interactions within the solid phase, solid-fluid interactions and the dynamics of the fluid phase. Yet, modelling one by one every single particle in problems at the field scale becomes highly computationally expensive, and, often, is still beyond the capacities of the existing computational resources. Therefore, a macro-scale rheological approach should be selected, moving from the particle-fluid mechanics to the continuum mechanics. The scientific problem of the debris flow rheology is a consequence of this continuum mechanics approach, e.g., [27,28].The code FLATModel, firstly introduced by [20] and subsequently reformulated in curvilinear coordinates in [29], implements a two-dimensional depth-averaged mathematical model of the shallow-water type, specifically designed to describe the propagation of debris fl...

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Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Preliminary Analysis For the Choice Of The Resistance Law Anmentioning

confidence: 99%

Section: Preliminary Analysis For the Choice Of The Resistance Law Anmentioning

confidence: 99%

mentioning

confidence: 99%

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Application of the 2D Depth-Averaged Model, FLATModel, to Pumiceous Debris Flows in the Amalfi Coast

Papa

Sarno

Vitiello

et al. 2018

Water

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Modelling and Terrestrial Laser Scanning Methodology (2009–2018) on Debris Cones in Temperate High Mountains

et al. 2020

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Debris cones are a very common landform in temperate high mountains. They are the most representative examples of the periglacial and nival processes. This work studies the dynamic behavior of two debris cones (Cone A and Cone B) in the Picos de Europa, in the north of the Iberian Peninsula. Their evolution was measured uninterruptedly throughout each August for 10 years (2009–2018) using the Terrestrial Laser Scanning (TLS) technique. The observations and calculations of the two debris cones were treated independently, but both showed the same behavior. Therefore, if these results are extrapolated to other debris cones in similar environments (temperate high mountain), they should show behavior similar to that of the two debris cones analyzed. Material falls onto the cones from the walls, and transfer of sediments follows linear trajectories according to the maximum slope. In order to understand the linear evolution of the two debris cones, profiles were created along the maximum slope lines of the Digital Elevation Model (DEM) of 2009, and these profile lines were extrapolated to the remaining years of measurement. In order to determine volumetric surface behavior in the DEMs, each year for the period 2009–2018 was compared. In addition, the statistical predictive value for position (Z) in year 2018 was calculated for the same planimetric position (X,Y) throughout the profiles of maximum slopes. To do so, the real field data from 2009–2017 were interpolated and used to form a sample of curves. These curves are interpreted as the realization of a functional random variable that can be predicted using statistical techniques. The predictive curve obtained was compared with the 2018 field data. The results of both coordinates (Z), the real field data, and the statistical data are coherent within the margin of error of the data collection.

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Field Surveys and Numerical Modeling of Pumiceous Debris Flows in Amalfi Coast (Italy)

Cited by 2 publications

References 23 publications

Application of the 2D Depth-Averaged Model, FLATModel, to Pumiceous Debris Flows in the Amalfi Coast

Application of the 2D Depth-Averaged Model, FLATModel, to Pumiceous Debris Flows in the Amalfi Coast

Modelling and Terrestrial Laser Scanning Methodology (2009–2018) on Debris Cones in Temperate High Mountains

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