scholarly journals The role of foliar litter-fall in forming channel morphology step-pool of high-gradient streams in Moravskoslezské Beskydy Mts.

Geografie ◽  
2017 ◽  
Vol 122 (1) ◽  
pp. 83-99 ◽  
Author(s):  
Libor Borák
Keyword(s):  
Grain Size ◽  
Woody Debris ◽  
Size Composition ◽  
Channel Morphology ◽  
Large Woody Debris ◽  
Litter Fall ◽  
Retention Capacity ◽  
Water Flows ◽  
The Impact

Channel morphology step-pool represents a morphodynamic complex influenced by large woody debris and litter-fall. The aim of this paper is to determine the impact of litter-fall on the channel morphology step-pool. General conclusions regarding the influence of litter-fall on channel morphology step-pool were based on results of geomorphological analyses. The study showed differences between river segments with or without foliaged steps. The pools following foliaged steps have a finer grain size composition of sediment. They are also larger, shallower and have a higher retention capacity. Foliaged steps help to decrease potential energy of water more effectively. If the litter-fall is permanently preserved at the step, it makes it more resistant to extreme water flows. As a result, it enables the development of a fully functional channel morphology step-pool.

The Role of Large Woody Debris in Beach‐Dune Interaction

2019 ◽  
Vol 124 (12) ◽  
pp. 2854-2876 ◽  
Author(s):  
M. J. Grilliot ◽  
I. J. Walker ◽  
B. O. Bauer
Keyword(s):  
Woody Debris ◽  
Large Woody Debris

scholarly journals Comparison of Large Woody Debris Prototypes in a Large Scale Non-flume Physical Model

2018 ◽  
Vol 40 ◽  
pp. 05010
Author(s):  
Brian Perry ◽  
Colin Rennie ◽  
Andrew Cornett ◽  
Paul Knox
Keyword(s):  
Physical Model ◽  
Flood Control ◽  
Large Scale ◽  
Woody Debris ◽  
Water Levels ◽  
Mitigation Strategies ◽  
Large Woody Debris ◽  
Debris Accumulation ◽  
The Impact ◽  
The City

Due to excessive rainfall in June of 2013, several rivers located in and near the City of Calgary, Canada experienced significant flooding events. These events caused severe damage to infrastructure throughout the city, precipitating a renewed interest in flood control and mitigation strategies for the area. A major potential strategy involves partial diversion of Elbow River flood water to the proposed Springbank Off-Stream Storage Reservoir. A large scale physical model study was conducted to optimize and validate the design of a portion of the new project. The goals of the physical model were to investigate diversion system behaviors such as flow rates, water levels, sediment transport and, debris accumulation, and optimize the design of new flow control structures to be constructed on the Elbow River. In order to accurately represent the behavior of debris within the system due to flooding, large woody debris created from natural sources was utilized in the physical model and its performance was compared to that of debris of the same size fabricated from pressed cylindrical wood dowels. In addition to comparing the performance of these two debris types, the impact of root wads on debris damming was also investigated. Significant differences in damming behavior was shown to exist between the natural debris and the fabricated debris, while the impact of root wad on damming affected the dam structure and formation. The results of this experiment indicate that natural debris is preferred for studies involving debris accumulation.

Grain Size in Mg Alloys: Recrystallization and Mechanical Consequences

2007 ◽  
Vol 558-559 ◽  
pp. 433-440 ◽  
Author(s):  
Matthew R. Barnett ◽  
Dale Atwell ◽  
Aiden G. Beer
Keyword(s):  
Grain Size ◽  
Dynamic Recrystallization ◽  
Grain Refinement ◽  
Magnesium Alloys ◽  
Mechanical Response ◽  
Deformation Twinning ◽  
Simultaneous Increase ◽  
The Impact ◽  
Strength And Ductility

The present paper examines the development of grain size during the recrystallization of magnesium alloys and the influence the grain size has on the mechanical response. In magnesium alloys grain refinement improves the strength-ductility balance. This simultaneous increase in both strength and ductility is ascribed to the impact the grain size has on deformation twinning. The mechanisms by which the grain size is established during hot working are shown to be conventional dynamic recrystallization followed by post-dynamic recrystallization. The role of alloying addition on both of these reactions is briefly considered.

scholarly journals Impact of the degree of grinding of siliceous opoka-like rocks on properties of ceramic products

2018 ◽  
Vol 251 ◽  
pp. 01010
Author(s):  
Julia Terekhina ◽  
Julia Bozhko ◽  
Kira Lapunova ◽  
Lyudmila Postoi
Keyword(s):  
Grain Size ◽  
Size Composition ◽  
Laboratory Research ◽  
Grain Size Composition ◽  
Molding Method ◽  
Bending Resistance ◽  
Application Potential ◽  
Processed Products ◽  
Ceramics Industry ◽  
The Impact

This work presents the results of the laboratory research on the impact of grain size composition of raw mixtures on properties of heat processed products when implementing the compression molding method. We have analyzed opokas of several fields: Zhuravksy, Shevchenkovsky and Bekeshevsky. Grain size composition of ground materials was characterized by a greater grain size of 0,315; 0,63; 1,25 and 2,5 mm. The link between degree of grinding and caking index, water absorption, mean density, compression and bending resistance was established. The conclusions based on the research results revealed the impact of grain size composition on properties of ceramic products and application potential of opokas as a feedstock in the ceramics industry.

scholarly journals Spatial Distribution of Large Woody Debris on the Snake River, Grand Teton National Park

1999 ◽  
Vol 23 ◽  
pp. 119-123
Author(s):  
Richard Marston ◽  
Robin Gray
Keyword(s):  
National Park ◽  
Woody Debris ◽  
Large River ◽  
Large Woody Debris ◽  
Snake River ◽  
Grand Teton National Park ◽  
Stream Morphology ◽  
Channel Bottom ◽  
The Relationship

Large woody debris (LWD) plays a key role in controlling the ecology and geomorphology of streams. Woody debris traps coarse particulate organic matter and sediments (Andersen and Sedell, 1979; Bilby and Likens, 1980; Marston, 1982); provides habitat for aquatic insects (Angermeier and Karr, 1984; Benke et al., 1985); and provides cover in pools and slow water areas (Bisson et al., 1982, 1987; Tschaplinski and Hartman, 1983; Fausch and Northcote, 1992). The role of wood in affecting stream morphology is dependent on the size of the stream (Bilby and Ward, 1989). In smaller streams, woody debris can create step pool sequences (Heede, 1972, 1985; Marston, 1982), increase pool area (Murphy and Hall, 1981; Ralph et al., 1994), and reduce sediment transport (Bilby, 1984). Nakamura and Swanson (1993) noted that the importance of woody debris to the morphology of first order streams can be limited by the size of the debris, which is often large enough to bridge the channel and not interact with the flow. Woody debris plays a larger role when it enters the channel bottom, where it can divert flow and affect erosion and deposition. The scale issues raised by Bilby and Ward (1989) and Nakamura and Swanson (1993) are critical to understanding the role of woody debris. To date, LWD has not been adequately studied at watershed scales in larger rivers. In fact, there is little understanding of the relationship between LWD and the geomorphic pattern of the river channel (Piegay and Marston, 1998; Piegay and Gumell, 1997; Piegay, 1993). The purpose of this study is to document the distribution of LWD jams on the Snake River in Grand Teton National Park, Wyoming in order to understand the effects of LWD on channel morphology in large river systems.

scholarly journals Sedimentological and geomorphological effects of the 1997 and 1998 flood sequence on the Lower Snowy River, Victoria

2016 ◽  
Vol 128 (2) ◽  
pp. 25 ◽  
Author(s):  
Wayne D. Erskine ◽  
Lisa M. Turner ◽  
Teresa A. Rose
Keyword(s):  
Grain Size ◽  
Channel Morphology ◽  
Peak Discharge ◽  
Maximum Depth ◽  
Peak Ratio ◽  
Flood Peak ◽  
Depth Ratio ◽  
Channel Boundary ◽  
Bed Material ◽  
The Impact

Three floods with flood peak ratios (peak discharge/mean annual flood) ranging between 0.65 and 5.35 occurred on the lower Snowy River in Victoria between June 1997 and August 1998. The June 1998 flood was the largest event downstream of the Rodger River junction where the flood peak ratio was >4. Pre- and post-flood investigations were carried out at the three Snowy River benchmarking sites in Victoria (McKillops Bridge, Sandy Point and Bete Bolong) to determine the impact of the floods on channel-boundary sediments and morphology. Few significant changes in graphic grain-size statistics for channel-boundary sediments were found at McKillops Bridge and Sandy Point. At Bete Bolong, there were many significant changes in the grain-size statistics of both the bed material and bank sediment. The variance and mean of a number of benchfull and bankfull channel morphologic parameters (width, area, mean depth, maximum depth, width‒maximum depth ratio) did not change significantly at McKillops Bridge and Sandy Point. At Bete Bolong, benchfull mean depth and area increased significantly due to bed degradation. Floods with a flood peak ratio of at least 4 are important for mobilising channel-boundary sediments and hence modifying channel morphology on the lower Snowy River.

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