Logjam Characteristics as Drivers of Transient Storage in Headwater Streams

Water Resources Research, Journal Year: 2023, Volume and Issue: 59(3)

Published: Feb. 23, 2023

Abstract Logjams in a stream create backwater conditions and locally force water to flow through the streambed, creating zones of transient storage within surface subsurface stream. We investigate relative importance logjam distribution density, permeability, discharge on simplified experimental channel. use physical flume experiments which we inject salt tracer, monitor fluid conductivity breakthrough curves water, determine breakthrough‐curve skewness characterize storage. then develop companion numerical model HydroGeoSphere reveal paths (or hyporheic zone) that contribute some longest transient‐storage timescales. In both simulations, observe formation an increase exchange at logjams. Observed complexities behavior depend largely zone. As expected, multiple successive logjams provide more pervasive by distributing head drop each jam, leading distributed but shallow paths. Decreasing permeability or increasing facilitate greater volumetric rate exchange. Understanding how characteristics affect solute transport channel zone has important management implications for rivers forested, historically environments.

Language: Английский

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Large Wood Transport and Accumulation Near the Separation Zone of a Channel Confluence

Water Resources Research, Journal Year: 2024, Volume and Issue: 60(3)

Published: March 1, 2024

Abstract Fallen trees enter the adjacent stream and are carried away downstream by current. As joins another one, complex hydrodynamics near their confluence make movement of wood hard to predict. These woods may accumulate resulting in backwater subsequent potential flooding. A laboratory study was conducted investigate accumulation behavior individual pieces confluence. The characteristics (i.e., length, diameter, density) hydraulic conditions discharge ratio release distance) were varied this investigation. It found that wooden released from tributary got occasionally trapped flow separation zone confluence, whereupon they mainly a clockwise vortex continued stay driven reverse cluster currents within zone. probability related its distance. effect diameter density tested parameters negligible. increased with an increase as well decrease longer had higher being trapped, whereas for those exceeding some critical value, nearly same, or dropped sharply. generalized model developed practical application. findings carry significant implications river management, particularly preventing risk flooding caused blockage.

Language: Английский

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Blockage of box-shaped and circular culverts under flood event conditions: a laboratory investigation

International Journal of River Basin Management, Journal Year: 2022, Volume and Issue: 21(4), P. 607 - 616

Published: April 10, 2022

Culverts are used to allow runoff pass through roads, railways, and embankments. Accumulation of debris during flood events reduces the culvert flow capacity hence overtopping results in failure both hydraulically structurally. This paper presents an experimental study temporal variations blockage upstream culverts due woody under unsteady conditions. To simulate conditions, a synthetic hydrograph was produced laboratory. Cylindrical wooden dowels with two different diameters were carrying events. Two shapes including box circular pipe examined here. The showed that maximum percentage occurs falling limb hydrograph. Although feeding rate smaller diameter into is considerable importance blockage, not influenced by large debris. It also found more susceptible than box-shaped culvert. Using regression analysis, predictive equations suggested estimate

Language: Английский

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Bridge obstruction caused by debris flow: A practical procedure for its management in debris-flow simulations

E3S Web of Conferences, Journal Year: 2023, Volume and Issue: 415, P. 05031 - 05031

Published: Jan. 1, 2023

Bridge clogging due to a debris flow is phenomenon scarcely studied but critical in hazard mapping the mountain area. Since rational and systematic approach still missing, we propose practical method deal with this numerical framework. We tested methodology by using, as model, two-phase, mobile-bed model TRENT2D and, site test case, village of Voueces north-west part Italian Alps. The application shows reasonable results highlights importance approach.

Language: Английский

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Physical modelling of large wood (LW) processes relevant for river management: Perspectives from New Zealand and Switzerland

Earth Surface Processes and Landforms, Journal Year: 2021, Volume and Issue: 47(1), P. 32 - 57

Published: June 30, 2021

Abstract In the last 30 years, work on large wood (LW) has expanded and matured considerably, river scientists, managers practitioners now have a better appreciation of role LW in maintaining ecosystems, forming or stabilizing riverine landforms, interacting with morphodynamics. We gained understanding hazards posed by recruitment transport channel associated infrastructure. While dynamics traditionally been studied natural environment, innovations laboratory techniques enabled important advances process dynamics, using physical scale models, new sensors, scanners sophisticated model boundary conditions. Current trends research focus (1) mobilization logs, (2) trapping deposition sediment presence (3) contribution to hydraulic flow resistance. Ultimately, combined is needed assess impacts upon infrastructure erodible boundaries, such as bridge piers retention racks. this review, we present critical analysis emerging experimental obtained through modelling studies. put recent context global management challenges. particular, set our environmental engineering issues that confront catchment resource Switzerland New Zealand. show how improved models incorporating transport, accumulation scouring processes are contribute more reliable hazard risk assessment LW‐prone systems.

Language: Английский

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Current progress in quantifying and monitoring instream large wood supply and transfer in rivers

Earth Surface Processes and Landforms, Journal Year: 2024, Volume and Issue: 49(1), P. 256 - 276

Published: Jan. 1, 2024

Abstract Large wood drives both the form and function of gravel‐bed rivers draining forested basins. Previously overlooked benefits in are now widely recognized. Together with flow sediment regimes, regime controls rivers' physical ecological integrity. Yet large quantities transported during floods can pose additional hazards, potentially damaging infrastructures like bridges or dams exacerbating flooding. However, unlike water regimes intensively studied over past decades, instream budgeting has been only recently defined thus is still rarely quantified. The budget describes cascading processes from supply recruitment, entrainment, transport to deposition, storage decay (i.e., fragmentation decomposition). These show high spatial temporal variability but be characterized by magnitude, frequency, timing, duration mode. Instream challenging, primarily because lack observations, monitoring stations, standardized protocols acquire data. This contribution reviews most recent advances quantify different components, notably supply, transfer. Case studies showing applications biogeochemistry, videography, artificial intelligence, numerical modelling tracking illustrate current progress. Because critical challenges remain, we identify describe some them discuss how riverine sciences may develop future.

Language: Английский

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Large wood fluctuation and longitudinal connectivity conditions along a segment of the Blanco River (Chilean Patagonia)

Geomorphology, Journal Year: 2024, Volume and Issue: 452, P. 109114 - 109114

Published: Feb. 27, 2024

Language: Английский

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The Effect of Large Wood Accumulations With Rootwads on Local Geomorphic Changes

Water Resources Research, Journal Year: 2022, Volume and Issue: 58(5)

Published: May 1, 2022

Abstract Large wood (LW) can be transported along a river during floods, increasing flood‐associated hazards, particularly when it accumulates at river‐spanning infrastructures such as bridges and weirs. While most flume studies have explored LW movement with simple wooden elements (dowels), only few used more complex geometries, rootwads, under unsteady flow conditions. Quantitative assessment of interactions amongst has rarely been attempted the effect this additional complication even ignored, in both field laboratory studies. In study, experiments were conducted to assess rootwads on local scour deposition mobile gravel‐bed. The experiment was conditions, constricted segment reach, recreating conditions accumulations blockage. Results revealed that tends generate stable than without leading formation porous loosely packed accumulations. initial set experiments, patterns quite variable, but average, showed spatially extensive disturbance bed. led development pits reached bottom quickly rootwads. mean accumulated bedload volumes similar magnitude overall, however, highlighting many contingencies chain processes between dam resultant bed scour.

Language: Английский

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Impacts of Channel‐Spanning Log Jams on Hyporheic Flow

Water Resources Research, Journal Year: 2023, Volume and Issue: 59(11)

Published: Nov. 1, 2023

Abstract In‐stream wood structures, such as single logs, river steps, and debris dams, are known to drive hyporheic flow, defined the flow that goes into subsurface region then back free‐flowing surface water. The plays an important role in regulating water quality biogeochemical cycles rivers. Here, we investigated impact of a channel‐spanning porous log jam, representing piles on through combination direct visualization theories. Specifically, developed method using refractive index‐matched sediment directly visualize around below formed by cylindrical rods, laboratory flume. We tracked velocity fluorescent dye moving transparent underneath jam. In addition, measured profile spatially varying near Our results show normalized jam‐induced flux remained smaller than 10% at Froude numbers () 0.06 increased factor five with increasing . combined mass momentum conservation equations Darcy's equation explain dependency Further, observed , dropped noticeably turbulent kinetic energy immediately downstream side These findings will facilitate future quantification caused jams.

Language: Английский

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Erosion and Deposition around Porous Engineered Log Jams: Flume Experiments and Improved Predictive Formulas

Journal of Hydraulic Engineering, Journal Year: 2024, Volume and Issue: 151(2)

Published: Dec. 23, 2024

Language: Английский

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