scholarly journals Supplementary material to "The effect of debris-flow sediment grain size distribution on fan forming processes"

2021 ◽  
Author(s):  
Haruka Tsunetaka ◽  
Norifumi Hotta ◽  
Yuichi Sakai ◽  
Thad Wasklewicz
Keyword(s):  
Grain Size ◽  
Debris Flow ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Sediment Grain Size ◽  
Supplementary Material

scholarly journals Debris flow sediment control using multiple herringbone water-sediment separation structures

2016 ◽  
Author(s):  
Xiangping Xie ◽  
Fangqiang Wei ◽  
Xiaojun Wang ◽  
Hongjuan Yang ◽  
James S. Gardner
Keyword(s):  
Grain Size ◽  
Debris Flow ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Sediment Grain Size ◽  
Sediment Control ◽  
Separation Rate ◽  
Control Effectiveness ◽  
Separation Ratio ◽  
Opening Width

Abstract. Single herringbone water-sediment separation structures (HWSS) have limited sediment control effectiveness in debris flows. A series of such structures in a debris flow channel to form a multiple structure system (M-HWSS system) should be more effective in debris flow mitigation. Hydraulic model tests reveal that a M-HWSS system does perform better in coarse sediment separation and has better stability in differing debris flow situations. The mean particle size of discharged sediment is gradually and significantly decreased down channel by M-HWSS system. The separated sediments are moderately sorted and this can be improved by optimizing the structure design parameters and increasing structure numbers. The fraction separation ratio (λi), coarse separation ratio (λc) and total sediment separation rate (Pt) are suggested parameters to express the sediment control effectiveness. All are closely related to the herringbone opening width and the input sediment grain size distribution. The quantitative relationships among them are proposed. On the basis of the tests, conclusions and guidelines for effective M-HWSS design include: (1) three structures in the M-HWSS located in succession upstream, midstream and downstream, each with substantially different in sediment control functions, (2) a structure's performance is strongly influenced by that of the preceding one so that every structure is designed to fully implement the sediment control function, especially for those in the upstream and midstream, (3)the suggested herringbone opening width in a structure should be set at the percentile of d50 ~ d84 of the input sediment grain size distribution so that 20 ~ 60 % of the effective separation rate can be achieved.

scholarly journals The effect of debris-flow sediment grain size distribution on fan forming processes

2021 ◽  
Author(s):  
Haruka Tsunetaka ◽  
Norifumi Hotta ◽  
Yuichi Sakai ◽  
Thad Wasklewicz
Keyword(s):  
Grain Size ◽  
Debris Flow ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Flow Characteristics ◽  
Granular Flows ◽  
Spatial Diversity ◽  
Flume Experiments ◽  
Sediment Grain Size ◽  
Average Grain Size

Abstract. Knowledge of the processes driving debris-flow fan evolution are critical in the support of efforts to mitigate related hazards, reduce risk to populations and infrastructure, and reconstruct the history of sediment dynamics in mountainous areas. Research on debris-flow fan development has focused on topographic controls, debris-flow volume and rheology, and the sequence of occurrence of debris flows. While these items have explained a great deal about fan formation and specifically avulsion and runout mechanisms, there is a need to further investigate other properties as they relate to debris-flow fan formative process. Here, we examined the role of debris-flow grain-size distribution on fan formation. Flume experiments were employed to examine the morphology of debris-flow fans that resulted from flows with mono- or multi-granular sediment composition with the same average grain size. All other flow characteristics were held constant. The mono-granular flows formed a symmetric-like fan morphology because there was little avulsion during the formation process. The multi-granular flows produced fans with an asymmetric morphology. Avulsions occurred on both lateral extents of the fan during the early stages of fan development and caused the runout direction to shift produce the fan asymmetry. Grain-size distribution was closely related to spatial diversity in fan morphology and stratigraphy.

Calculating debris flow density based on grain-size distribution

Landslides ◽  
2019 ◽  
Vol 16 (3) ◽  
pp. 515-522
Author(s):  
Taiqiang Yang ◽  
Yong Li ◽  
Qishu Zhang ◽  
Yu Jiang
Keyword(s):  
Grain Size ◽  
Debris Flow ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Flow Density

Study on the downcutting rate of a debris flow dam based on grain-size distribution

Geomorphology ◽  
2021 ◽  
pp. 107891
Author(s):  
Hechun Ruan ◽  
Huayong Chen ◽  
Yong Li ◽  
Jiangang Chen ◽  
Huibin Li
Keyword(s):  
Grain Size ◽  
Debris Flow ◽  
Size Distribution ◽  
Grain Size Distribution

scholarly journals Sediment transport modelling in riverine environments: on the importance of grain-size distribution, sediment density and boundary conditions

2018 ◽  
Author(s):  
Jérémy Lepesqueur ◽  
Renaud Hostache ◽  
Núria Martínez-Carreras ◽  
Emmanuelle Montargès-Pelletier ◽  
Christophe Hissler
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Size Distribution ◽  
Suspended Sediment ◽  
Grain Size Distribution ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Small Scale ◽  
Sediment Grain Size ◽  
Model Based

Abstract. Hydromorphodynamic models are powerful tools to predict the potential mobilization and transport of sediment in river ecosystems. Recent studies even showed that they are able to satisfyingly predict suspended sediment matter concentration in small river systems. However, modelling exercises often neglect suspended sediment properties (e.g. particle site distribution and density), even though such properties are known to directly control the sediment particle dynamics in the water column during rising and flood events. This study has two objectives. On the one hand, it aims at further developing an existing hydromorphodynamic model based on the dynamic coupling of TELEMAC-3D (v7p1) and SISYPHE (v7p1) in order to enable an enhanced parameterisation of the sediment grain size distribution with distributed sediment density. On the other hand, it aims at evaluating and discussing the added-value of the new development for improving sediment transport and riverbed evolution predictions. To this end, we evaluate the sensitivity of the model to sediment grain size distribution, sediment density and suspended sediment concentration at the upstream boundary condition. As a test case, the model is used to simulate a flood event in a small scale river, the Orne River in North-eastern France. The results show substantial discrepancies in bathymetry evolution depending on the model setup. Moreover, the sediment model based on an enhanced sediment grain size distribution (10 classes) and with distributed sediment density outperforms the model with only two sediment grain size classes in terms of simulated suspended sediment concentration.

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