PALAEOENVIRONMENTAL OBSERVATIONS ON A LATE HOLOCENE DEBRIS-FLOW PROCESS IN LAKE ASSOM (ADAMAWA, CAMEROON)

2013 ◽  
pp. 135-154
Keyword(s):  
Debris Flow ◽  
Late Holocene ◽  
Flow Process

scholarly journals A Hydrodynamic-Based Robust Numerical Model for Debris Hazard and Risk Assessment

2021 ◽  
Vol 13 (14) ◽  
pp. 7955
Author(s):  
Yongde Kang ◽  
Jingming Hou ◽  
Yu Tong ◽  
Baoshan Shi
Keyword(s):  
Numerical Model ◽  
Debris Flow ◽  
Finite Volume ◽  
Graphics Processing Unit ◽  
Morphological Changes ◽  
Finite Volume Scheme ◽  
Processing Unit ◽  
Algebraic Equations ◽  
Flow Process ◽  
Computing Technique

Debris flow simulations are important in practical engineering. In this study, a graphics processing unit (GPU)-based numerical model that couples hydrodynamic and morphological processes was developed to simulate debris flow, transport, and morphological changes. To accurately predict the debris flow sediment transport and sediment scouring processes, a GPU-based parallel computing technique was used to accelerate the calculation. This model was created in the framework of a Godunov-type finite volume scheme and discretized into algebraic equations by the finite volume method. The mass and momentum fluxes were computed using the Harten, Lax, and van Leer Contact (HLLC) approximate Riemann solver, and the friction source terms were calculated using the proposed splitting point-implicit method. These values were evaluated using a novel 2D edge-based MUSCL scheme. The code was programmed using C++ and CUDA, which can run on GPUs to substantially accelerate the computation. After verification, the model was applied to the simulation of the debris flow process of an idealized example. The results of the new scheme better reflect the characteristics of the discontinuity of its movement and the actual law of the evolution of erosion and deposition over time. The research results provide guidance and a reference for the in-depth study of debris flow processes and disaster prevention and mitigation.

scholarly journals EDDA: integrated simulation of debris flow erosion, deposition and property changes

2014 ◽  
Vol 7 (6) ◽  
pp. 7267-7316
Author(s):  
H. X. Chen ◽  
L. M. Zhang
Keyword(s):  
Debris Flow ◽  
Yield Stress ◽  
Water Flow ◽  
Large Scale ◽  
Limit Equilibrium ◽  
Flow Density ◽  
Catchment Scale ◽  
Flow Process ◽  
One Dimensional ◽  
Property Changes

Abstract. Debris flow material properties change during the initiation, transportation and deposition processes, which influences the runout characteristics of the debris flow. A quasi-three-dimensional depth-integrated numerical model, EDDA, is presented in this paper to simulate debris flow erosion, deposition and induced material property changes. The model considers changes in debris flow density, yield stress and dynamic viscosity during the flow process. The yield stress of debris flow mixture is determined at limit equilibrium using the Mohr–Coulomb equation, which is applicable to clear water flow, hyper-concentrated flow and fully developed debris flow. To assure numerical stability and computational efficiency at the same time, a variable time stepping algorithm is developed to solve the governing differential equations. Four numerical tests are conducted to validate the model. The first two tests involve a one-dimensional dam-break water flow and a one-dimensional debris flow with constant properties. The last two tests involve erosion and deposition, and the movement of multi-directional debris flows. The changes in debris flow mass and properties due to either erosion or deposition are shown to affect the runout characteristics significantly. The model is also applied to simulate a large-scale debris flow in Xiaojiagou Ravine to test the performance of the model in catchment-scale simulations. The results suggest that the model estimates well the volume, inundated area, and runout distance of the debris flow. The model is intended for use as a module in a real-time debris flow warning system.

scholarly journals Laboratory and field tests and distinct element analysis of dry granular flows and segregation processes

2019 ◽  
Vol 19 (1) ◽  
pp. 181-199 ◽  
Author(s):  
Yung Ming Cheng ◽  
Wing Hong Ivan Fung ◽  
Liang Li ◽  
Na Li
Keyword(s):  
Debris Flow ◽  
Numerical Simulations ◽  
Granular Flow ◽  
Laboratory Tests ◽  
Large Scale ◽  
Distinct Element ◽  
Field Tests ◽  
Flow Process ◽  
Flume Tests ◽  
Dry Granular Flow

Abstract. Natural as well as fill slopes are commonly found in Hong Kong, China, and many other countries, and slope failures with the subsequent debris flows have caused a serious loss of life and property in the past until now. There are various processes and features associated with debris flow which engineers need to know so as to design for the precautionary measures. In this study, experiments on flume tests, friction tests, deposition tests, and rebound tests were carried out for different sizes of balls to determine the parameters required for the modelling of dry granular flow. Different materials and sizes of balls are used in the flume tests, and various flow pattern and segregation phenomena are noticed in the tests. Distinct element modelling (DEM) of dry granular flow is also carried out for the flow process. It is found that for simple cases, the flow process can be modelled reasonably well by DEM, which is crucial for engineers to determine the pattern and impact of granular flow, which will lead to further study in more complicated debris flow. From laboratory tests, large-scale field tests, and numerical simulations of single- and multiple-material tests, it is also found that the particle size will be the most critical factor in the segregation process during granular flow. It is also found from the laboratory tests and numerical simulations that a jump in the flume can help to reduce the final velocity of the granular flow, which is useful for practical purposes.

Comprehensive Research and Outlook of Loose Solid Materials on the Gully System under Hydrodynamic Conditions

2012 ◽  
Vol 212-213 ◽  
pp. 40-45 ◽  
Author(s):  
Shun Yang ◽  
Guo Qiang Ou ◽  
Xian Jun Ji ◽  
Jun Wang
Keyword(s):  
Debris Flow ◽  
Hydrodynamic Effect ◽  
Initial Condition ◽  
Hydrodynamic Conditions ◽  
Slope Surface ◽  
Flume Experiments ◽  
Solid Materials ◽  
Flow Process ◽  
Artificial Rainfall ◽  
The Relationship

The paper reviewed the research and progress of solid materials on the gully system in the world and pointed out the shortage of it. On the condition of hydrodynamics, many papers available concentrated on the relationship between rainfall parameters and debris flow occurrence, rainfall infiltration and surface runoff; while on the solid materials on the gully or slope surface, a lot of researches focused on the flume experiments to analyses the initial condition and debris flow process under hydrodynamic effect together with artificial rainfall. Base on the reviews previous, paper give some prospects of research under hydrodynamic conditions in the futures.

scholarly journals Unraveling the patterns of late Holocene debris-flow activity on a cone in the Swiss Alps: Chronology, environment and implications for the future

2008 ◽  
Vol 60 (3-4) ◽  
pp. 222-234 ◽  
Author(s):  
Markus Stoffel ◽  
Delphine Conus ◽  
Michael A. Grichting ◽  
Igor Lièvre ◽  
Gilles Maître
Keyword(s):  
Debris Flow ◽  
Late Holocene ◽  
Swiss Alps ◽  
The Future ◽  
Flow Activity

Late Holocene geomorphic record of fire in ponderosa pine and mixed-conifer forests, Kendrick Mountain, northern Arizona, USA

2011 ◽  
Vol 20 (1) ◽  
pp. 125 ◽  
Author(s):  
Sara E. Jenkins ◽  
Carolyn Hull Sieg ◽  
Diana E. Anderson ◽  
Darrell S. Kaufman ◽  
Philip A. Pearthree
Keyword(s):  
Debris Flow ◽  
Ponderosa Pine ◽  
Debris Flows ◽  
Late Holocene ◽  
Conifer Forests ◽  
Fire Behaviour ◽  
Mixed Conifer ◽  
Northern Arizona ◽  
Mixed Conifer Forests ◽  
Steep Slopes

Long-term fire history reconstructions enhance our understanding of fire behaviour and associated geomorphic hazards in forested ecosystems. We used 14C ages on charcoal from fire-induced debris-flow deposits to date prehistoric fires on Kendrick Mountain, northern Arizona, USA. Fire-related debris-flow sedimentation dominates Holocene fan deposition in the study area. Radiocarbon ages indicate that stand-replacing fire has been an important phenomenon in late Holocene ponderosa pine (Pinus ponderosa) and ponderosa pine–mixed conifer forests on steep slopes. Fires have occurred on centennial scales during this period, although temporal hiatuses between recorded fires vary widely and appear to have decreased during the past 2000 years. Steep slopes and complex terrain may be responsible for localised crown fire behaviour through preheating by vertical fuel arrangement and accumulation of excessive fuels. Holocene wildfire-induced debris flow events occurred without a clear relationship to regional climatic shifts (decadal to millennial), suggesting that interannual moisture variability may determine fire year. Fire-debris flow sequences are recorded when (1) sufficient time has passed (centuries) to accumulate fuels; and (2) stored sediment is available to support debris flows. The frequency of reconstructed debris flows should be considered a minimum for severe events in the study area, as fuel production may outpace sediment storage.

scholarly journals EDDA 1.0: integrated simulation of debris flow erosion, deposition and property changes

2015 ◽  
Vol 8 (3) ◽  
pp. 829-844 ◽  
Author(s):  
H. X. Chen ◽  
L. M. Zhang
Keyword(s):  
Debris Flow ◽  
Yield Stress ◽  
Water Flow ◽  
Large Scale ◽  
Limit Equilibrium ◽  
Flow Density ◽  
Catchment Scale ◽  
Flow Process ◽  
Runout Distance ◽  
Property Changes

Abstract. Debris flow material properties change during the initiation, transportation and deposition processes, which influences the runout characteristics of the debris flow. A quasi-three-dimensional depth-integrated numerical model, EDDA (Erosion–Deposition Debris flow Analysis), is presented in this paper to simulate debris flow erosion, deposition and induced material property changes. The model considers changes in debris flow density, yield stress and dynamic viscosity during the flow process. The yield stress of the debris flow mixture determined at limit equilibrium using the Mohr–Coulomb equation is applicable to clear water flow, hyper-concentrated flow and fully developed debris flow. To assure numerical stability and computational efficiency at the same time, an adaptive time stepping algorithm is developed to solve the governing differential equations. Four numerical tests are conducted to validate the model. The first two tests involve a one-dimensional debris flow with constant properties and a two-dimensional dam-break water flow. The last two tests involve erosion and deposition, and the movement of multi-directional debris flows. The changes in debris flow mass and properties due to either erosion or deposition are shown to affect the runout characteristics significantly. The model is also applied to simulate a large-scale debris flow in Xiaojiagou Ravine to test the performance of the model in catchment-scale simulations. The results suggest that the model estimates well the volume, inundated area, and runout distance of the debris flow. The model is intended for use as a module in a real-time debris flow warning system.

Late Holocene debris cone evolution in Glen Feshie, western Cairngorm Mountains, Scotland

1989 ◽  
Vol 80 (1) ◽  
pp. 17-24 ◽  
Author(s):  
Vanessa Brazier ◽  
Colin K. Ballantyne
Keyword(s):  
Debris Flow ◽  
Fifteenth Century ◽  
Late Holocene ◽  
Buried Soils ◽  
Lateral Migration ◽  
Flow Units ◽  
Vegetation Disturbance ◽  
River Erosion ◽  
Cone Development ◽  
Debris Cone

ABSTRACTRecent river erosion of three coalescing debris cones in Glen Feshie has exposed a complex sequence of debris flow units. Radiocarbon dating of organic matter from interbedded buried soils reveals that the soil at the base of the sequence was buried at c. 2000 yr BP, but that the bulk of the cones accumulated since the fifteenth century AD. The episodic nature of cone development is attributable to lateral migration of the River Feshie, with periods of cone accumulation when the river occupied the far side of its floodplain alternating with periods of erosion when the river impinged on the cones. There is no evidence to suggest that recent cone accumulation is related to anthropogenic vegetation disturbance, but phases of cone accumulation show a broad temporal correspondence with periods of Late Holocene climatic deterioration. The cones are essentially paraglacial in that their continuing accumulation depends on a supply of sediment derived from glacial and periglacial deposits upslope. The form of debris-flow units indicates that flows at this site were less viscous than most ‘hillslope’ flows, and cone volumes indicate an average annual accumulation of c. 50–60 m3 of sediment over the past c. 300years.

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