Laboratory Flume Experiments on the Formation of Spanwise Large Wood Accumulations: Part II—Effect on local scour

Schalko, Isabella; Lageder, C.; Schmocker, Lukas; Weitbrecht, Volker; Boes, Robert M.

doi:10.1029/2019wr024789

Cited by 61 publications

(63 citation statements)

References 19 publications

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“…During infrequent, high‐magnitude events, floods and debris flows may transport and deposit large quantities of large wood, enhancing the potential for damage to populations and infrastructure (Ruiz‐Villanueva et al ., 2014b, 2018; Lucía et al ., 2015; Steeb et al ., 2017). At narrow sections of river valleys, or bridges, weirs, and dams that have not been properly designed to allow the wood to pass (Lassettre and Kondolf, 2012), the deposition of large wood may cause a significant reduction in channel cross‐sectional area, causing backwater flooding (Ruiz‐Villanueva et al ., 2017), local scour and erosion (Pagliara and Carnacina, 2011; Schalko et al ., 2019), sediment deposition, and bed aggradation or channel avulsion. Therefore, it is not surprising that large wood studies in these regions have focused on wood recruitment, transport, and deposition at short timescales (i.e.…”

Section: Case Studiesmentioning

confidence: 99%

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Reflections on the history of research on large wood in rivers

Swanson

Gregory

Iroumé

et al. 2020

Earth Surf Processes Landf

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Dynamics and functions of large wood have become integral considerations in the science and management of river systems. Study of large wood in rivers took place as monitoring of fish response to wooden structures placed in rivers in the central United States in the early 20th century, but did not begin in earnest until the 1970s. Research has increased in intensity and thematic scope ever since. A wide range of factors has prompted these research efforts, including basic understanding of stream systems, protection and restoration of aquatic ecosystems, and environmental hazards in mountain environments. Research and management have adopted perspectives from ecology, geomorphology, and engineering, using observational, experimental, and modelling approaches. Important advances have been made where practical information needs converge with institutional and science leadership capacities to undertake multi‐pronged research programmes. Case studies include ecosystem research to inform regulations for forest management; storage and transport of large wood as a component in global carbon dynamics; and the role of wood transport in environmental hazards in mountain regions, including areas affected by severe landscape disturbances, such as volcanic eruptions. As the field of research has advanced, influences of large wood on river structures and processes have been merged with understanding of streamflow and sediment regimes, so river form and function are now viewed as involving the tripartite system of water, sediment, and wood. A growing community of researchers and river managers is extending understanding of large wood in rivers to climatic, forest, landform, and social contexts not previously investigated. © 2020 John Wiley & Sons, Ltd.

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Section: Case Studiesmentioning

confidence: 99%

“…Flow conditions leading up to obstructions drive the probability of large wood accumulation (e.g. Schalko, 2018; Schalko et al ., 2019). The design of the structure in terms of bridge deck and pier shape may influence the magnitude of wood blockage (Schmocker and Hager, 2011; Comiti et al, 2012; Gschnitzer et al ., 2017).…”

Section: Case Studiesmentioning

confidence: 99%

Reflections on the history of research on large wood in rivers

Swanson

Gregory

Iroumé

et al. 2020

Earth Surf Processes Landf

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“…i. Overflowing structures such as dam spillways, PK weirs and our closed dam exhibit the smallest h/h 0 values ranging 0 %-50 % (Hartlieb, 2012(Hartlieb, , 2017Schmocker, 2017;Furlan, 2019;Pfister et al, 2013aPfister et al, , b, 2020, with lower values when a rack or protruding piles are set upstream of the spillway (Schmocker, 2017;Furlan, 2019;Pfister et al, 2020).…”

Section: Comparison With Existing Studiesmentioning

confidence: 93%

“…The first question has been addressed for reservoir dams: for ogee crest spillways with piles by Hartlieb (2012Hartlieb ( , 2017, Schmocker (2017) and Pfister et al (2020) and for piano-key weirs (PK weirs) by Pfister et al (2013b). It was also recently thoroughly covered by the hydraulic research team of ETH Zürich for rack structures made of poles (Schalko, 2020;Schalko et al, 2018Schalko et al, , 2019aSchmocker and Hager, 2013;Schmocker and Weitbrecht, 2013;Schmocker et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Open check dams and large wood: head losses and release conditions

Piton¹,

Horiguchi²,

Marchal³

et al. 2020

Nat. Hazards Earth Syst. Sci.

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Abstract. Open check dams are strategic structures to control sediment and large-wood transport during extreme flood events in steep streams and piedmont rivers. Large wood (LW) tends to accumulate at such structures, obstruct their openings and increase energy head losses, thus increasing flow levels. The extent and variability to which the stage–discharge relationship of a check dam is modified by LW presence has so far not been clear. In addition, sufficiently high flows may trigger a sudden release of the trapped LW with eventual dramatic consequences downstream. This paper provides experimental quantification of LW-related energy head loss and simple ways to compute the related increase in water depth at dams of various shapes: trapezoidal, slit, slot and sabo (i.e. made of piles), with consideration of the flow capacity through their open bodies and atop their spillways. In addition, it was observed that LW is often released over the structure when the overflowing depth, i.e. total depth minus spillway elevation, is about 3–5 times the mean log diameter. Two regimes of LW accumulations were observed. Dams with low permeability generate low velocity upstream, and LW then accumulates as floating carpets, i.e. as a single floating layer. Conversely, dams with high permeability maintain high velocities immediately upstream of the dams and LW tends to accumulate in dense complex 3D patterns. This is because the drag forces are stronger than the buoyancy, allowing the logs to be sucked below the flow surface. In such cases, LW releases occur for higher overflowing depth and the LW-related head losses are higher. A new dimensionless number, namely the buoyancy-to-drag-force ratio, can be used to compute whether (or not) flows stay in the floating-carpet domain where buoyancy prevails over drag force.

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“…As one such material being transported in rivers, driftwood has recently received considerable attention in various research and engineering studies (e.g., [1,2]). This is because the large pieces of wood have many roles in river systems; they can provide a large variety of flow and sediment transport fields thereby creating rich habitats for many aquatic species [3], have a non-negligible effect on the landscapes [4,5], and increase flood risks [6][7][8]. A better understanding of wood recruitment, transport, deposition, and remobilization is therefore an important research topic in the fields of environmental and engineering research [9].…”

Section: Introductionmentioning

confidence: 99%

The Role of Large-Scale Bedforms in Driftwood Storage Mechanism in Rivers

Okitsu

Iwasaki

Kyuka

et al. 2021

Water

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The quantification of driftwood deposition in rivers is important for understanding the total budget of driftwood at the watershed scale; however, it remains unclear how such driftwood storage in rivers contributes to the overall system because of the difficulties in undertaking field measurements. Herein, we perform numerical simulations of driftwood deposition within an idealized river reach with a sand-bed, to describe the role of large-scale bedforms, more specifically, alternate bars, multiple bars, and braiding, in driftwood storage in rivers. The numerical model we propose here is a coupling model involving a Lagrangian-type driftwood model and an Eulerian two-dimensional morphodynamic model for simulating large-scale bedforms (i.e., bars and braiding). The results show that the channel with a braiding pattern provides a wide area with enhanced capacity for deposition of driftwood, characterized by exposed mid-channel or in-channel bars, leading to high driftwood storage. The alternate bar is also a large bedform representing a sediment depositional element in rivers; however, because of the narrow exposed bar area and its downstream-migrating feature during floods, the alternate bars seem to contribute less to driftwood deposition in rivers. This suggests that the role of multiple bars and braiding is critically important for the driftwood deposition in rivers.

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Laboratory Flume Experiments on the Formation of Spanwise Large Wood Accumulations: Part II—Effect on local scour

Cited by 61 publications

References 19 publications

Reflections on the history of research on large wood in rivers

Reflections on the history of research on large wood in rivers

Open check dams and large wood: head losses and release conditions

The Role of Large-Scale Bedforms in Driftwood Storage Mechanism in Rivers

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