Impacts of an extreme flood on large wood recruitment and transport processes

2021 ◽  
pp. 1-29
Author(s):  
Derek J. Martin ◽  
Robert T. Pavlowsky ◽  
Jacob Bendix ◽  
Toby Dogwiler ◽  
Josh Hess
Keyword(s):  
Transport Processes ◽  
Large Wood ◽  
Extreme Flood

scholarly journals Modelling Spatiotemporal Dynamics of Large Wood Recruitment, Transport, and Deposition at the River Reach Scale during Extreme Floods

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1134 ◽  
Author(s):  
Andreas Zischg ◽  
Niccolo Galatioto ◽  
Silvana Deplazes ◽  
Rolf Weingartner ◽  
Bruno Mazzorana
Keyword(s):  
Simulation Model ◽  
Transport Model ◽  
Large Wood ◽  
Flow Paths ◽  
Extreme Floods ◽  
Reliable Assessment ◽  
Extreme Flood ◽  
Floodplain Inundation ◽  
Irregular Meshes ◽  
River Reach

Large wood (LW) can lead to clogging at bridges and thus cause obstruction, followed by floodplain inundation. Moreover, colliding logs can cause severe damage to bridges, defense structures, and other infrastructure elements. The factors influencing spatiotemporal LW dynamics (LWD) during extreme floods vary remarkably across river basins and flood scenarios. However, there is a lack of methods to estimate the amount of LW in rivers during extreme floods. Modelling approaches allow for a reliable assessment of LW dynamics during extreme flood events by determining LW recruitment, transport, and deposition patterns. Here, we present a method for simulating LWD on a river reach scale implemented in R (LWDsimR). We extended a previously developed LW transport model with a tree recognition model on the basis of Light Detection and Ranging (LiDAR) data for LW recruitment simulation. In addition, we coupled the LWD simulation model with the hydrodynamic simulation model Basic Simulation Environment for Computation of Environmental Flow and Natural Hazard Simulation (BASEMENT-ETH) by adapting the existing LW transport model to be used on irregular meshes. The model has been applied in the Aare River basin (Switzerland) to quantify mobilized LW volumes and the associated flow paths in a probable maximum flood scenario.

scholarly journals Brief communication: The curious case of the large wood-laden flow event in the Pocuro stream (Chile)

2017 ◽  
Vol 17 (11) ◽  
pp. 2053-2058 ◽  
Author(s):  
Diego Ravazzolo ◽  
Luca Mao ◽  
Bruno Mazzorana ◽  
Virginia Ruiz-Villanueva
Keyword(s):  
Initial Phase ◽  
Large Wood ◽  
Flood Events ◽  
Additional Source ◽  
Good Opportunity ◽  
Mountain Environments ◽  
Direct Observations ◽  
Extreme Flood ◽  
Large Wood Transport ◽  
Wood Transport

Abstract. Large wood transported during extreme flood events can represent a relevant additional source of hazards that should be taken into account in mountain environments. However, direct observations and monitoring of large-wood transport during floods are difficult and scarce. Here we present a video of a flood characterised by multiple phases of large-wood transport, including an initial phase of wood-laden flow rarely described in the literature. Estimations of flow velocity and transported wood volume provide a good opportunity to develop models of large-wood-congested transport.

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

2020 ◽  
Vol 20 (12) ◽  
pp. 3293-3314
Author(s):  
Guillaume Piton ◽  
Toshiyuki Horiguchi ◽  
Lise Marchal ◽  
Stéphane Lambert
Keyword(s):  
Drag Force ◽  
Dimensionless Number ◽  
Large Wood ◽  
Low Velocity ◽  
Head Losses ◽  
Drag Forces ◽  
Check Dams ◽  
Flow Surface ◽  
Extreme Flood ◽  
Relationship Of

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.

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

2020 ◽  
Author(s):  
Guillaume Piton ◽  
Toshiyuki Horiguchi ◽  
Lise Marchal ◽  
Stéphane Lambert
Keyword(s):  
Energy Dissipation ◽  
Single Layer ◽  
Bedload Transport ◽  
Dimensionless Number ◽  
Large Wood ◽  
Low Velocity ◽  
Head Losses ◽  
Drag Forces ◽  
Check Dams ◽  
Extreme Flood

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 against such structures, to obstruct their openings and to increase energy dissipation and thus, flow levels. To which extent open check dams' stage-discharge relationships are consequently modified by LW presence was not clear so far. This question is key (i) to estimate how much bedload transport might be trapped in the related backwater areas and (ii) to estimate how high is the overflowing depth atop the structure. These flows, when sufficiently high, might trigger a sudden release of the previously trapped LW with eventual dramatic consequences downstream. This paper provides experimental quantification of LW-related energy dissipation 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), including flow capacity through their open body and atop the spillway. It was additionally observed that LW is often released over the structure when the overflowing depth, i.e., depth above the spillway, is about 3–5 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 floating single layer. Conversely, dams with high permeability maintain high velocities close to the dams and LW tends to jam them in dense complex 3D patterns because drag forces are stronger than buoyancy and logs are sucked below the flow surface. In such cases, LW releases occur for higher overflowing depth and LW-related head losses are higher. A new dimensionless number, namely the ratio buoyancy to drag force, enables to compute whether or not flows stay in the floating carpet domain where buoyancy prevails.

scholarly journals Brief communication: The curious case of the large wood-laden flow event in the Pocuro stream (Chile)

2017 ◽  
Author(s):  
Diego Ravazzolo ◽  
Luca Mao ◽  
Bruno Mazzorana ◽  
Virginia Ruiz-Villanueva
Keyword(s):  
Flow Velocity ◽  
Initial Phase ◽  
Large Wood ◽  
Flood Events ◽  
Additional Source ◽  
Good Opportunity ◽  
Mountain Environments ◽  
Extreme Flood ◽  
Large Wood Transport ◽  
Wood Transport

Abstract. Large wood transported during extreme flood events can represent a relevant additional source of hazards that should be taken into account in mountain environments. However, direct observation and monitoring of large wood transport during floods are difficult and scarce. Here we present a video of a flood characterized by multiple phases of large wood transport, including an initial phase of wood-laden flow, rarely described in literature. Estimations of flow velocity and transported wood volumes provide a good opportunity for developing models of large wood congested transport.

scholarly journals Displacement length and velocity of tagged logs in the tagliamento river

2013 ◽  
Vol 44 (2s) ◽  
Author(s):  
Diego Ravazzolo ◽  
L. Mao ◽  
B. Garniga ◽  
L. Picco ◽  
M.A. Lenzi
Keyword(s):  
Cross Sections ◽  
Positive Relationship ◽  
Transport Processes ◽  
Large Wood ◽  
Flood Events ◽  
Gravel Bed ◽  
North East ◽  
High Magnitude ◽  
Tagliamento River ◽  
Gravel Bed Rivers

Large wood enhance the dynamics of geomorphic processes in river systems, increases the morphological complexity of the channel bed, and provides habitats for fish and invertebrates. On the other side, if transported during high-magnitude events, large wood pieces can increase flood risks in sensitive places such as bridges and narrow cross sections prone to outbank flows. However, the dynamics and mobility of logs in rivers is poorly understood, especially in wide gravel-bed rivers. Recent studies have employed fixed video cameras to assess logs velocity, but little evidence is still available about travel length during flood events of different magnitude. This study was conducted in a valley reach of the Tagliamento river, located in the North East of Italy. The Tagliamento river is approximately 800 m wide in the study area, and is characterized by relatively high natural conditions and complex fluvial dynamics. Log mobility have been studied from June 2010 to October 2011, a period characterized by a relatively high magnitude flood in November 2010. Log mobility and displacement during floods have been measured by implanting active radio transmitters (RFID) in 113 logs and GPS track devices in 42 logs. The first devices allow to recover the log after flood events by using a portable antenna, and to derive the displacement length over the monitoring period, whereas the second devices allows to calculate instantaneous (1 sec) and average log velocity of moving logs. Recovery rate of logs equipped with RFID and GPS was about 50% and 60%, respectively. A preliminary analysis of the data collected indicates that there is a positive relationship between displacement length and the peak of flood events, as well as a positive relationship between log velocity and the flood magnitude. Also, a critical flow rate over which logs stranded on active bars can be transported has been identified. The ability to predict wood mobility in gravel-bed rivers could allow to define better strategies of river management and restoration, by improving the ability to understand wood transport processes and calibrate budgets of wood in rivers.

Large wood recruitment processes and transported volumes in Swiss mountain streams during the extreme flood of August 2005

Geomorphology ◽  
2017 ◽  
Vol 279 ◽  
pp. 112-127 ◽  
Author(s):  
Nicolas Steeb ◽  
Dieter Rickenmann ◽  
Alexandre Badoux ◽  
Christian Rickli ◽  
Peter Waldner
Keyword(s):  
Mountain Streams ◽  
Large Wood ◽  
Extreme Flood

Saturn's E, G and F rings: modulated by the plasma sheet

1984 ◽  
Vol 75 ◽  
pp. 597
Author(s):  
E. Grün ◽  
G.E. Morfill ◽  
T.V. Johnson ◽  
G.H. Schwehm
Keyword(s):  
Solar Wind ◽  
Direct Contact ◽  
Transport Processes ◽  
Time Variable ◽  
Dust Particles ◽  
Spatial Diffusion ◽  
Drag Forces ◽  
Orbit Perturbation ◽  
Time Variations ◽  
F Ring

ABSTRACTSaturn's broad E ring, the narrow G ring and the structured and apparently time variable F ring(s), contain many micron and sub-micron sized particles, which make up the “visible” component. These rings (or ring systems) are in direct contact with magnetospheric plasma. Fluctuations in the plasma density and/or mean energy, due to magnetospheric and solar wind processes, may induce stochastic charge variations on the dust particles, which in turn lead to an orbit perturbation and spatial diffusion. It is suggested that the extent of the E ring and the braided, kinky structure of certain portions of the F rings as well as possible time variations are a result of plasma induced electromagnetic perturbations and drag forces. The G ring, in this scenario, requires some form of shepherding and should be akin to the F ring in structure. Sputtering of micron-sized dust particles in the E ring by magnetospheric ions yields lifetimes of 102to 104years. This effect as well as the plasma induced transport processes require an active source for the E ring, probably Enceladus.

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