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

Ravazzolo, Diego; Mao, Luca; Mazzorana, Bruno; Ruíz-Villanueva, Virginia

doi:10.5194/nhess-17-2053-2017

Cited by 17 publications

(12 citation statements)

References 17 publications

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“…Pioneering observations described wood as an important component in debris flow deposits (Swanson and Lienkaemper, 1978;Nakagawa et al, 1994;May, 2002;Lancaster et al, 2003;Shrestha et al, 2012), but flows in which wood is the main solid fraction (both in terms of mass and volume) have Table S1. Examples have been recently reported for mountain streams in Chile and Switzerland (Ravazzolo et al, 2017;Ruiz-Villanueva et al, 2017). We follow here the nomenclature of particle-laden flows (Delannay et al, 2017) to define woodladen flows (WLFs) as a class of two-or three-phase flow.…”

Section: Introductionmentioning

confidence: 90%

“…The main phase consists of wood pieces of different sizes, that might be transported in water (second phase), in which inorganic sediment (both suspended and bedload) can be present (third phase). Examples have been recently reported for mountain streams in Chile and Switzerland (Ravazzolo et al, 2017;Ruiz-Villanueva et al, 2017).…”

Section: Introductionmentioning

confidence: 90%

“…WLFs might be powerful agents of morphodynamic change in river corridors and can pose grave hazards to people and property, as evidenced by past events in which the transport of wood during floods and debris flows enhanced the negative consequences of such events (Ruiz- Villanueva et al, 2013Villanueva et al, , 2014bComiti et al, 2016;Ravazzolo et al, 2017;Steeb et al, 2017).…”

Section: Implications For Hazards and River Managementmentioning

confidence: 99%

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Characterization of wood‐laden flows in rivers

Ruíz-Villanueva

Mazzorana

Castellet

et al. 2019

Earth Surf Processes Landf

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Inorganic sediment is not the only solid‐fraction component of river flows; flows may also carry significant amounts of large organic material (i.e. large wood), but the characteristics of these wood‐laden flows (WLFs) are not well understood yet. With the aim to shed light on these relatively unexamined phenomena, we collected home videos showing natural flows with wood as the main solid component. Analyses of these videos as well as the watersheds and streams where the videos were recorded allowed us to define for the first time WLFs, describe the main characteristics of these flows and broaden the definition of wood transport regimes (adding a new regime called here hypercongested wood transport). According to our results, WLFs may occur repeatedly, in a large range of catchment sizes, generally in steep, highly confined single thread channels in mountain areas. WLFs are typically highly unsteady and the log motion is non‐uniform, as described for other inorganic sediment‐laden flows (e.g. debris flows). The conceptual integration of wood into our understanding of flow phenomena is illustrated by a novel classification defining the transition from clear water to hypercongested, wood and sediment‐laden flows, according to the composition of the mixture (sediment, wood, and water). We define the relevant metrics for the quantification and modelling of WLFs, including an exhaustive discussion of different modelling approaches (i.e. Voellmy, Bingham and Manning) and provide a first attempt to simulate WLFs. We draw attention to WLF phenomena to encourage further field, theoretical, and experimental investigations that may contribute to a better understanding of flows in river basins, leading to more accurate predictions, and better hazard mitigation and management strategies. © 2019 John Wiley & Sons, Ltd.

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Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 90%

Section: Implications For Hazards and River Managementmentioning

confidence: 99%

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Characterization of wood‐laden flows in rivers

Ruíz-Villanueva

Mazzorana

Castellet

et al. 2019

Earth Surf Processes Landf

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“…() used two video cameras to monitor the passage of wood during floods and ice‐breakup events in the Saint‐Jean River in Canada. As for flood discharge data (Le Coz et al ., ), web‐crowdsourced home movies have been recently used to define and characterize wood‐laden flows (Ravazzolo et al ., ; Ruiz‐Villanueva et al ., ) (Figure C). Automatic and semi‐automatic wood detection procedures have been developed to track and quantify the wood discharge in the images (Benacchio et al ., ), but the systematic application still requires further research (Piégay et al ., ).…”

Section: Remote Sensing To Identify Patterns and Acting Processesmentioning

confidence: 99%

Remotely sensed rivers in the Anthropocene: state of the art and prospects

Piégay

Arnaud

Belletti

et al. 2020

Earth Surf Processes Landf

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103

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The rivers of the world are undergoing accelerated change in the Anthropocene, and need to be managed at much broader spatial and temporal scales than before. Fluvial remote sensing now offers a technical and methodological framework that can be deployed to monitor the processes at work and to assess the trajectories of rivers in the Anthropocene. In this paper, we review research investigating past, present and future fluvial corridor conditions and processes using remote sensing and we consider emerging challenges facing fluvial and riparian research. We introduce a suite of remote sensing methods designed to diagnose river changes at reach to regional scales. We then focus on identification of channel patterns and acting processes from satellite, airborne or ground acquisitions. These techniques range from grain scales to landform scales, and from real time scales to inter-annual scales. We discuss how remote sensing data can now be coupled to catchment scale models that simulate sediment transfer within connected river networks. We also consider future opportunities in terms of datasets and other resources which are likely to impact river management and monitoring at the global scale. We conclude with a summary of challenges and prospects for remotely sensed rivers in the Anthropocene.

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“…logs are transported in bulk) [4], or hypercongested (i.e. not saturated logs are transported in bulk at the front) [5]. Congested or hypercongested LW transport can result in enormous accumulations at river infrastructures during a flood event.…”

Section: Introductionmentioning

confidence: 99%

Hazards due to large wood accumulations: Local scour and backwater rise

et al. 2018

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Large wood (LW) in rivers increases the flow variability and provides habitats for various species. During flood events, transported logs can accumulate at river infrastructures and increase the flood hazard. LW accumulations result in an upstream backwater rise and may increase local scour, for instance at bridge piers. Consequently, estimates of the resulting backwater rise and local scour are necessary to improve the flood hazard assessment. This study presents the findings of flume experiments with a movable bed on local scour and backwater rise due to LW accumulations. The approach flow conditions and the bed material were varied systematically for a specific LW accumulation volume. For all experiments, the initial condition for the bed material was defined as weak transport, since the bed shear stress was slightly below the critical bed shear stress for incipient motion. The inflow Froude number was identified as the governing parameter for backwater rise due to LW accumulations. The present study confirms the hypothesis that the resulting local scour reduces backwater rise. For the local scour, the unit discharge and the grain size diameter are the decisive parameters.

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

Cited by 17 publications

References 17 publications

Characterization of wood‐laden flows in rivers

Characterization of wood‐laden flows in rivers

Remotely sensed rivers in the Anthropocene: state of the art and prospects

Hazards due to large wood accumulations: Local scour and backwater rise

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