Critical conditions of bed sediment entrainment due to debris flow

Papa, Maria Nicolina; Egashira, Shinji; Itoh, Takahiro

doi:10.5194/nhess-4-469-2004

Cited by 55 publications

(42 citation statements)

References 7 publications

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“…However, recent contributions to the mechanics of debris flow initiation has investigated the influence of the mechanical behaviour of sediments at the onset of a debris flow, particularly analysing the shear resistance variation of a granular soil in relation to the initial densities and to the collapse potential of the soil [20]. Other recent researches have been carried out in Italy on incipient sediment motion at high slopes [23,49,50] but need more applications.…”

Section: Debris Flow Research Perspectivesmentioning

confidence: 99%

“…Other numerical models were developed during the last two decades based on different assumptions [14][15][16][17][18][19]. Studies and researches on critical conditions of bed sediment entrainment due to debris flow, factors triggering debris flow, the determination of rheological characteristics of debris flow, configurations of debris-flow fan and run-out distances, based on flume tests, numerical and dimensional analysis, has also been carried out in Italy by many Authors [20][21][22][23][24][25][26].…”

Section: Hydraulic Studies On Debris Flowsmentioning

confidence: 99%

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Research developments in debris flow monitoring, modelling and hazard assessment in Italian mountain catchments

Lenzi¹

2006

WIT Transactions on Ecology and the Environment, Vol 90

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Debris flows play an important role among natural hazards in the mountainous areas of Italy. This paper provides an overview of the recent research on debris flows conducted in Italy, taking into account both hydraulic and morphological studies. Moreover, the most encouraging research perspectives in this field are briefly presented, such as the monitoring in instrumented basins, the geotechnical analysis of the processes leading to debris flow initiation and modelling. Finally, three study cases are reported, with the aim of outlining the main characteristics of these phenomena and the consequent risk conditions in representative sites in the Italian mountains.

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Section: Debris Flow Research Perspectivesmentioning

confidence: 99%

Section: Hydraulic Studies On Debris Flowsmentioning

confidence: 99%

Research developments in debris flow monitoring, modelling and hazard assessment in Italian mountain catchments

Lenzi¹

2006

WIT Transactions on Ecology and the Environment, Vol 90

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“…This process can lead to a substantial bulking of a debris flow surge, resulting in a significant increase of material transported down to the fan. There are only limited flume and field measurements on channel bed erosion and subsequent bulking of the flow [e.g., Rickenmann et al, 2003;Papa et al, 2004;Berger et al, 2011;McCoy et al, 2012]. Theoretical models for debris-flow entrainment were developed and discussed in some studies Fagents and Baloga, 2006;Iverson, 2012;McCoy et al, 2012].…”

Section: Debris Flow Initiation and Erosion Along The Flow Pathmentioning

confidence: 99%

Debris-Flow Hazard Assessment and Methods Applied in Engineering Practice

Rickenmann

2016

IJECE

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Debris flows constitute a major natural hazard in mountainous regions. The main elements required for a practical hazard assessment include the following steps: (i) estimation of potential initiation zones and sediment sources, (ii) establishment of a relation between the magnitude and frequency of expected future debris-flow events, and (iii) assessment of the flow behavior and delineation of areas potentially endangered by flowing debris. A general overview is presented of the main triggering conditions and initiation mechanisms for debris-flow formation. A brief summary is given of methods to establish a magnitude-frequency relation and to estimate the total volume of sediments transported to the fan during so-called "design" events. To assess the runout distance of debris flows and potentially affected areas, either simple empirical approaches or more physically based numerical simulation models may be used. An example application for a Swiss debris fan illustrates the variability of the results when using three different debris-flow simulation models, even though all three models were first calibrated based on the observed deposition areas of a past event.

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“…Unfortunately, there are only few works regarding the unsteady non-uniform sediment transport, and unsteady flows are usually treated with expressions that have been developed for a uniform flow condition (Papa et al, 2004;Egashira et al, 2001;Franzi, 2001;Correira et al, 1992;Takahashi, 1991) that is often described as the "equilibrium condition" (Seminara, 1998). This approach is incorrect for purely unsteady flows, for which the immediate achievement of transport capacity, which actually occurs in equilibrium conditions, is not ensured (Armanini and Di Silvio, 1988).…”

Section: Introductionmentioning

confidence: 99%

An expression for the water-sediment moving layer in unsteady flows valid for open channels and embankments

Berta

Bianco

2010

Nat. Hazards Earth Syst. Sci.

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Abstract. During the floods, the effects of sediment transport in river beds are particulary significant and can be studied through the evolution of the water-sediment layer which moves in the lower part of a flow, named "moving layer". Moving layer variations along rivers lead to depositions and erosions and are typically unsteady, but are often tackled with expressions developed for steady (equilibrium) conditions. In this paper, we develop an expression for the moving layer in unsteady conditions and calibrate it with experimental data. During laboratory tests, we have in fact reproduced a rapidly changing unsteady flow by the erosion of a granular steep slope. Results have shown a clear tendency of the moving layer, for fixed discharges, toward equilibrium conditions. Knowing the equilibrium achievement has presented many difficulties, being influenced by the choice of the equilibrium expression and moreover by the estimation of the parameters involved (for example friction angle). Since we used only data relevant to hyper-concentrated mono-dimensional flows for the calibration -occurring for slope gradients in the range 0.03-0.20 -our model can be applied both on open channels and on embankments/dams, providing that the flows can be modelled as mono-dimensional, and that slopes and applied shear stress levels fall within the considered ranges.

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Critical conditions of bed sediment entrainment due to debris flow

Cited by 55 publications

References 7 publications

Research developments in debris flow monitoring, modelling and hazard assessment in Italian mountain catchments

Research developments in debris flow monitoring, modelling and hazard assessment in Italian mountain catchments

Debris-Flow Hazard Assessment and Methods Applied in Engineering Practice

An expression for the water-sediment moving layer in unsteady flows valid for open channels and embankments

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