scholarly journals Sedimentological characteristics of debris flow Deposits within ice−cored moraine of Ebbabreen, central Spitsbergen

2015 ◽  
Vol 36 (2) ◽  
pp. 125-144 ◽  
Author(s):  
Krzysztof Pleskot
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Slope Angle ◽  
Parent Material ◽  
Original Structure ◽  
Sediment Layer ◽  
Local Conditions ◽  
Thin Sections ◽  
Sedimentary Characteristics ◽  
Deposition Area

Abstract The Ebbabreen ice−cored moraine area is covered with a sediment layer of up to 2.5 m thick, which mostly consists of massive diamicton. Due to undercutting by lateral streams, debris flow processes have been induced in marginal parts of this moraine. It was recognized that the sedimentology of deposits within the deposition area of debris flows is the effect of: (1) the origin of the sediments, (2) the nature of the debris flow, and (3) post−debris flow reworking. Analysis of debris flow deposits in microscale (thin sections) suggests a common mixing during flow, even though a small amount of parent material kept its original structure. The mixing of sediments during flow leads to them having similar sedimentary characteristics across the deposition area regardless of local conditions (i.e. slope angle, water content, parent material lithology). After the deposition of sediments that were transported by the debris flow, they were then reworked by a further redeposition process, primarily related to meltwater stream action.

scholarly journals The Development of a 1-D Integrated Hydro-Mechanical Model Based on Flume Tests to Unravel Different Hydrological Triggering Processes of Debris Flows

Water ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 950 ◽  
Author(s):  
Theo van Asch ◽  
Bin Yu ◽  
Wei Hu
Keyword(s):  
Debris Flow ◽  
Mechanical Model ◽  
Debris Flows ◽  
Overland Flow ◽  
Slope Angle ◽  
Great Influence ◽  
Flume Experiments ◽  
Triggering Mechanisms ◽  
Bed Material ◽  
Triggering Process

Many studies which try to analyze conditions for debris flow development ignore the type of initiation. Therefore, this paper deals with the following questions: What type of hydro-mechanical triggering mechanisms for debris flows can we distinguish in upstream channels of debris flow prone gullies? Which are the main parameters controlling the type and temporal sequence of these triggering processes, and what is their influence on the meteorological thresholds for debris flow initiation? A series of laboratory experiments were carried out in a flume 8 m long and with a width of 0.3 m to detect the conditions for different types of triggering mechanisms. The flume experiments show a sequence of hydrological processes triggering debris flows, namely erosion and transport by intensive overland flow and by infiltrating water causing failure of channel bed material. On the basis of these experiments, an integrated hydro-mechanical model was developed, which describes Hortonian and saturation overland flow, maximum sediment transport, through flow and failure of bed material. The model was calibrated and validated using process indicator values measured during the experiments in the flume. Virtual model simulations carried out in a schematic hypothetical source area of a catchment show that slope angle and hydraulic conductivity of the bed material determine the type and sequence of these triggering processes. It was also clearly demonstrated that the type of hydrological triggering process and the influencing geometrical and hydro-mechanical parameters may have a great influence on rainfall intensity-duration threshold curves for the start of debris flows.

scholarly journals Sedimentology, dynamics and debris flow potential of Champadevi River, southwest Kathmandu, Nepal

1970 ◽  
Vol 10 ◽  
pp. 9-20
Author(s):  
Naresh Kazi Tamrakar ◽  
Achut Prajapati ◽  
Suman Manandhar
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Alluvial Fan ◽  
Shear Stresses ◽  
Stream Power ◽  
Huge Amount ◽  
Sedimentary Characteristics ◽  
Unconsolidated Material ◽  
Flow Potential ◽  
Headward Erosion

Mountainous and hilly regions are potential for debris flows, one of the major forms of natural disasters, which cause serious damage in downstream areas. The southwestern region of the Kathmandu Valley experienced catastrophic flows in the Champadevi River and its two tributaries (the Aitabare and the Raute Rivers) in July 2002. These rivers were investigated for morphologic, hydraulic and sedimentary characteristics to evaluate potential of debris flow in the area. The Raute and the Aitabare Rivers have tendency of headward erosion due to abrupt drop of gradient down the scarp of the alluvial fan deposit composed of unconsolidated matrix-supported gravel and mud. Because of this tendency, the rivers erode their substrate and banks, and contribute slope movements by sheding a huge amount of clasts and matrix. Therefore, instability condition of rivers and unconsolidated material available in the river courses potentially contribute for debris flow. The tractive shear stresses in the Aitabare, the Raute and the Champadevi Rivers (1.27, 1.60 and 0.48 KPa, respectively) exceeds twice the critical shear stresses required to transport 90th-percentile fraction of the riverbed material (0.14, 0.18 and 0.11 KPa). The stream powers (10.8, 17.2 and 5.1 m-kN/s/m2) of these rivers also greatly exceed the critical stream powers (0.21, 0.35 and 0.18 m-kN/s/m2) required to initiate traction transport. Because the tractive shear stresses and the stream powers that are achieved during bankfull flow are several times larger than the corresponding critical values, even the flow having stream power exceeding the critical stream power may potentially generate debris flow.   doi: 10.3126/bdg.v10i0.1416 Bulletin of the Department of Geology, Tribhuvan University, Kathmandu, Nepal, Vol. 10, 2007, pp. 9-20

scholarly journals Creating a national scale debris flow susceptibility model for Great Britain: a GIS-based heuristic approach

2019 ◽  
Author(s):  
Emma J. Bee ◽  
Claire Dashwood ◽  
Catherine Pennington ◽  
Roxana L. Ciurean ◽  
Katy Lee
Keyword(s):  
Great Britain ◽  
Debris Flow ◽  
Debris Flows ◽  
Methodological Approach ◽  
Slope Angle ◽  
Transport Infrastructure ◽  
Stream Channels ◽  
National Scale ◽  
Susceptibility Model ◽  
Debris Flow Susceptibility

Abstract. Debris flows in Great Britain have caused damage to transport infrastructure, buildings, and disruption to businesses and communities. This study describes a GIS-based heuristic model developed by the British Geological Survey (BGS) to produce a national scale spatial assessment of debris flow susceptibility for Great Britain. The model provides information on the potential for debris flow occurrence using properties and characteristics of geological materials (permeability, material availability and characteristics when weathered), slope angle and proximity to stream channels as indicators of susceptibility. Building on existing knowledge, the model takes into account the presence or absence of glacial scouring. As determined by the team of geologists and geomorphologists, the model ranks the availability of debris material and slope as the two dominant factors important for potential debris flow initiation, however it also considers other factors such as geological controls on infiltration. The resultant model shows that over 90 % of the mapped debris flows in the BGS inventory occurred in areas with the highest potential for instability and approximately 6 % were attributed to areas where the model suggested that debris flows are unlikely or not thought to occur. Model validation in the Cairngorm Mountains indicated a better performance, with 93.50 % in the former and less than 3 % in the latter category. Although the quality of the input datasets and selected methodological approach bear limitations and introduce a number of uncertainties, overall, the proposed susceptibility model performs better than previous attempts, representing a useful tool in the hands of policy-makers, developers and engineers to support regional or national scale development action plans and disaster risk reduction strategies.

Holocene debris flows and environmental history, Hazelton area, British Columbia

1991 ◽  
Vol 28 (10) ◽  
pp. 1583-1593 ◽  
Author(s):  
Allen S. Gottesfeld ◽  
Rolf W. Mathewes ◽  
Leslie M. Johnson Gottesfeld
Keyword(s):  
British Columbia ◽  
Debris Flow ◽  
Oral History ◽  
Environmental History ◽  
Debris Flows ◽  
Plant Macrofossils ◽  
Sediment Layer ◽  
Catastrophic Event ◽  
Outlet Stream ◽  
History Of

Debris flow deposits of Chicago Creek and the sediment, pollen, and macrofossil records of Seeley Lake were studied to elucidate the Holocene history of the northwest flank of the Rocher Déboulé Range near Hazelton, British Columbia.The Chicago Creek drainage has experienced numerous rockfalls, debris slides, and debris flows. A large debris flow covering approximately 300 ha occurred about 3580 ± 150 BP. This flow was two to three orders of magnitude larger than historic debris flows in this drainage. It traveled about 3 km down Chicago Creek and dammed the outlet stream of Seeley Lake. A debris deposit along lower Chicago Creek is interpreted as the product of debris torrents that formed during or soon after the damming of Seeley Lake. Its surface exhibits soil development (rubification and profile development) comparable to that on the large debris flow, suggesting equivalent age.Pollen and plant macrofossils are described from a core taken in Seeley Lake. This core spans the period from ca. 9200 BP to the present. A disturbance event in 3380 ± 110 BP, correlative with the large Chicago Creek debris flow, is recorded by a clastic sediment layer and changes in the microfossil and macrofossil assemblages.The Chicago Creek debris flow and debris torrent ca. 3500 BP may be the catastrophic event recorded in the story of the Medeek, an oral history or "ada'ok" of the Gitksan people of Hazelton.

scholarly journals The Development of a 1-D Integrated Hydro-Mechanical Model Based on Flume Tests, to Unravel Different Hydrological Triggering Processes of Debris Flows

2018 ◽  
Author(s):  
Theo W.J. van Asch ◽  
Bin Yu ◽  
Wei Hu
Keyword(s):  
Debris Flow ◽  
Mechanical Model ◽  
Debris Flows ◽  
Overland Flow ◽  
Slope Angle ◽  
Great Influence ◽  
Flume Experiments ◽  
Triggering Mechanisms ◽  
Bed Material ◽  
Triggering Process

Many studies, which try to analyze conditions for debris flow development, ignore the type of initiation. Therefore this paper deals with the following questions: What type of hydro-mechanical triggering mechanisms for debris flows can we distinguish in upstream channels of debris flow prone gullies? Which are the main parameters controlling the type and temporal sequence of these triggering processes and what is their influence on the meteorological thresholds for debris flow initiation? A series of laboratory experiments were carried out in a flume, 8 m long and with a width of 0.3 m. to detect the conditions for different types of triggering mechanisms. The flume experiments show a sequence of hydrological processes triggering debris flows, namely erosion and transport by intensive overland flow and by infiltrating water causing failure of channel bed material. On the basis of these experiments an integrated hydro-mechanical model was developed, which describes Hortonian and Saturation overland flow, maximum sediment transport, through flow and failure of bed material. The model was calibrated and validated using process indicator values measured during the experiments in the flume. Virtual model simulations, carried out in a schematic hypothetical source area of a catchment show that slope angle and hydraulic conductivity of the bed material determine the type and sequence of these triggering processes. It was also clearly demonstrated that the type of hydrological triggering process and the influencing geometrical and hydro-mechanical parameters may have a great influence on rainfall intensity-duration threshold curves for the start of debris flows.

scholarly journals Predicting the Initiation Area of a Debris Flow Using Geomorphological Characteristics and a Physically-Based Model

2021 ◽  
Vol 21 (2) ◽  
pp. 137-147
Author(s):  
Chang-Ho Song ◽  
Ji-Sung Lee ◽  
Yun-Tae Kim
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Physically Based Model ◽  
Index Analysis ◽  
Geotechnical Characteristics ◽  
Deposition Area ◽  
Significant Damage ◽  
Physically Based ◽  
Error Index ◽  
Success Index

A debris flow is a phenomenon in which sediment matter and water become mixed and flow down to a deposition area, thereby causing significant damage to people and property. In Korea, majority of the past debris flows initiated in the form of shallow landslides during rainfall. To address the hazards associated with debris flows, it is necessary to establish a method for predicting the location of the debris flow initiation. In this study, we propose a method for predicting the source of a debris flow by incorporating geomorphological characteristics and designing a physically-based model. The geomorphological characteristics associated with the initiation area of the debris flow were determined by analyzing previous literature. The physically-based model was developed by incorporating landslide inventory data, rainfall data, and geotechnical characteristics, and the map of safety factor less than 1.2 was thereby established. Furthermore, the region prone to the occurrence of debris flows was identified by the superposition of each unstable pixel obtained from the geomorphological characteristics and the physically-based model. The proposed method was validated through quantitative index analysis. The obtained results indicate that compared to other methods, the proposed method has a high success index and a low error index for predicting the source of a debris flow.

scholarly journals Learning Case Study of a Shallow-Water Model to Assess an Early-Warning System for Fast Alpine Muddy-Debris-Flow

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 750
Author(s):  
Antonio Pasculli ◽  
Jacopo Cinosi ◽  
Laura Turconi ◽  
Nicola Sciarra
Keyword(s):  
Debris Flow ◽  
Shallow Water ◽  
Early Warning ◽  
Debris Flows ◽  
Early Warning System ◽  
Warning System ◽  
Extreme Weather Events ◽  
Water Model ◽  
Computational Time ◽  
Processing Unit

The current climate change could lead to an intensification of extreme weather events, such as sudden floods and fast flowing debris flows. Accordingly, the availability of an early-warning device system, based on hydrological data and on both accurate and very fast running mathematical-numerical models, would be not only desirable, but also necessary in areas of particular hazard. To this purpose, the 2D Riemann–Godunov shallow-water approach, solved in parallel on a Graphical-Processing-Unit (GPU) (able to drastically reduce calculation time) and implemented with the RiverFlow2D code (version 2017), was selected as a possible tool to be applied within the Alpine contexts. Moreover, it was also necessary to identify a prototype of an actual rainfall monitoring network and an actual debris-flow event, beside the acquisition of an accurate numerical description of the topography. The Marderello’s basin (Alps, Turin, Italy), described by a 5 × 5 m Digital Terrain Model (DTM), equipped with five rain-gauges and one hydrometer and the muddy debris flow event that was monitored on 22 July 2016, were identified as a typical test case, well representative of mountain contexts and the phenomena under study. Several parametric analyses, also including selected infiltration modelling, were carried out in order to individuate the best numerical values fitting the measured data. Different rheological options, such as Coulomb-Turbulent-Yield and others, were tested. Moreover, some useful general suggestions, regarding the improvement of the adopted mathematical modelling, were acquired. The rapidity of the computational time due to the application of the GPU and the comparison between experimental data and numerical results, regarding both the arrival time and the height of the debris wave, clearly show that the selected approaches and methodology can be considered suitable and accurate tools to be included in an early-warning system, based at least on simple acoustic and/or light alarms that can allow rapid evacuation, for fast flowing debris flows.

scholarly journals Numerical Simulation of Non-Homogeneous Viscous Debris-Flows Based on the Smoothed Particle Hydrodynamics (SPH) Method

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2314 ◽  
Author(s):  
Shu Wang ◽  
Anping Shu ◽  
Matteo Rubinato ◽  
Mengyao Wang ◽  
Jiping Qin
Keyword(s):  
Debris Flow ◽  
Water Content ◽  
Smoothed Particle Hydrodynamics ◽  
Debris Flows ◽  
Sph Method ◽  
Particle Hydrodynamics ◽  
Sph Model ◽  
Smoothed Particle ◽  
The Impact ◽  
Kinetic And Potential Energies

Non-homogeneous viscous debris flows are characterized by high density, impact force and destructiveness, and the complexity of the materials they are made of. This has always made these flows challenging to simulate numerically, and to reproduce experimentally debris flow processes. In this study, the formation-movement process of non-homogeneous debris flow under three different soil configurations was simulated numerically by modifying the formulation of collision, friction, and yield stresses for the existing Smoothed Particle Hydrodynamics (SPH) method. The results obtained by applying this modification to the SPH model clearly demonstrated that the configuration where fine and coarse particles are fully mixed, with no specific layering, produces more fluctuations and instability of the debris flow. The kinetic and potential energies of the fluctuating particles calculated for each scenario have been shown to be affected by the water content by focusing on small local areas. Therefore, this study provides a better understanding and new insights regarding intermittent debris flows, and explains the impact of the water content on their formation and movement processes.

The Debris Flow Disaster Faster-Than-Early Forecast System (DFS) with Multi-Sensors Integrated Wireless Sensor Networks

2013 ◽  
Vol 347-350 ◽  
pp. 975-979
Author(s):  
Rong Zhao ◽  
Cai Hong Li ◽  
Yun Jian Tan ◽  
Jun Shi ◽  
Fu Qiang Mu ◽  
...  
Keyword(s):  
Wireless Sensor Networks ◽  
Sensor Networks ◽  
Debris Flow ◽  
Real Time ◽  
Debris Flows ◽  
Base Station ◽  
Base Stations ◽  
Wireless Sensor ◽  
Forecast System ◽  
Debris Flow Disaster

This paper presents a Debris Flow Disaster Faster-than-early Forecast System (DFS) with wireless sensor networks. Debris flows carrying saturated solid materials in water flowing downslope often cause severe damage to the lives and properties in their path. Faster-than-early or faster-than-real-time forecasts are imperative to save lives and reduce damage. This paper presents a novel multi-sensor networks for monitoring debris flows. The main idea is to let these sensors drift with the debris flow, to collect flow information as they move along, and to transmit the collected data to base stations in real time. The Raw data are sent to the cloud processing center from the base station. And the processed data and the video of the debris flow are display on the remote PC. The design of the system address many challenging issues, including cost, deployment efforts, and fast reaction.

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