Virginia Ruiz-Villanueva

University of Lausanne | UNIL · Institute of Earth Surface Dynamics (IDYST)

Mountain rivers are prone to flash floods, and in forested basins, large quantities of wood can be moved and transported long distances downstream during such events. Under certain circumstances, congested transport of wood may result in wood-laden flows in which a large number of logs form a mass moving together with the flow and thus alter its dy...

Large wood is an important physical component of woodland rivers and significantly influences river morphology. It is also a key component of stream ecosystems. However, large wood is also a source of risk for human activities as it may damage infrastructure, block river channels, and induce flooding. Therefore, the analysis and quantification of l...

The transport of wood material in rivers has been the subject of various studies in recent years. Most research has focused on the ecological and geomorphologic role of wood, its recruitment processes and spatial distribution in streams. In this study, we focused on wood transport dynamics, and we have developed a numerical model to simulate wood t...

Floods can mobilize large amounts of unconsolidated material, which also includes large wood in forested river basins. Yet, the influence of the shape and volume of flood hydrographs on wood dynamics in rivers remains poorly understood. Quantitative data on this relation are, however, critically needed to properly address management strategies and...

Large wood tends to be deposited in specific geomorphic units within rivers. Nevertheless, predicting the spatial distribution of wood deposits once wood enters a river is still difficult because of the inherent complexity of its dynamics. In addition, the lack of long-term observations or monitored sites has usually resulted in a rather incomplete...

Large wood (LW) is an integral component of watercourses. However, we still need to gain more knowledge of the geomorphic processes related to LW in large lower-energy, meandering rivers due to the limited number of field studies dealing with LW transport and retention in these widespread fluvial systems. This study aims to detect the predictors of...

Different models have been used in science and practice to identify instream large wood (LW) sources and to estimate LW supply to rivers. This contribution reviews the existing models proposed in the last 35 years and compares two of the most recent GIS-based models by applying them to 40 catchments in Switzerland. Both models, which we call here e...

Instream large wood increases biodiversity in river systems. However, due to wood-related damages to villages and infrastructure during floods, river managers are posed a question: leave it in or take it out? To better understand the process of wood transport in rivers, we have developed an automatic instream wood detection system, based on a machi...

Accumulation of instream large wood (i.e., fallen trees, trunks, branches, and roots) at bridges during floods may exacerbate scour and cause structural failure. Yet, explaining and predicting the likelihood of a bridge trapping wood remains challenging. Quantitative data regarding wood accumulation at bridges are scarce, and most studies have been...

Large wood (LW) accumulations can cause several damages, especially if the recruited wood is transported during floods down to urban areas, like Lourdes (France). One of the most serious problems concerning bridges and weirs all around the world is the formation of LW accumulations, that might be responsible for the structure’s failure. However, th...

Mountain rivers can convey significant amounts of coarse sediment (gravel, cobble), and large wood pieces; both recruited from river margins and valley slopes. The erosion, transport, and deposition of this material may endanger human infrastructures, such as bridge piles, canals, or weirs, notably increasing flood hazards and potential damages. Th...

Integrating flow-sediment and wood regimes in the design of e-flows (i.e., environmental or experimental flows, floods, or releases) is of great importance, particularly in forested rivers with unregulated tributaries and /or active hillslopes affected by mass movements processes. In such cases, large quantities of sediment and wood can be supplied...

Accumulated driftwood (i.e., floating trunks, downed trees, branches, and roots) upstream from dams may create obstructions, reduce spillway capacity, and cause undesired higher water levels in the reservoir. To minimize these issues, some dam managers must remove the driftwood mechanically regularly. This is the case at the Génissiat dam in the Rh...

Large wood (10cm diameter & 1m long) gets recruited into a mountain river system from surrounding forested areas. Instream large wood positively influences the diversity of the river system, creating habitats for terrestrial and aquatic species. However, the corresponding risk to the presence of instream large wood is a more controversial topic in...

Within the field of dendrochronology, different sub-disciplines arise using the information stored in the wood for a variety of purposes. In this study, we use dendroprovenance to develop a methodology that allows us to infer the source area of instream large wood (LW) at the river basin scale applying fingerprinting techniques. LW is mainly suppli...

Large wood (LW) has earned increased attention as a component of fluvial systems as its ecological and physical benefits, as well as its contributions to damages during flood events, have been realized. As LW found in river networks had originated from outside of the channel corridor, significant efforts have been made to identify recruitment proce...

Floods and intense surface runoff are recurring hazards known for triggering erosion processes at the channel and the catchment slope scales, respectively. Whilst the firsts determine the removal of streambank material, also referred to as hydraulic streambank erosion (e.g., Ruiz-Villanueva et al., 2014), the seconds are typically responsible for d...

Many geomorphologists who are mothers find it challenging to balance field research alongside pregnancy and early motherhood. The barriers presented by carrying out fieldwork during pregnancy or as a mother of preschool-aged children can adversely affect the career progress of women and Early Career Scientists at a point that is critical for their...

Large and relatively immobile sediment particles (i.e., boulders, usually defined with a diameter greater than 256 mm) are naturally delivered to rivers from hillslopes, transported by extreme floods, or produced by processes such as bed armouring. Boulder placement is also used as an artifical method for stabilizing channel beds and banks in river...

This work was completed prior to my first year review at UNIL. It features preliminary findings and the general workflow to how the project plans to be completed.

Driftwood in river catchments might pose a hazard for the safety of infrastructures, such as dams and river dwellers, and thus is often removed. Génissiat dam in France presents a case study where annually approximately 1300 tons of driftwood are removed to prevent driftwood sinking and to protect the dam infrastructure. Collected river driftwood i...

Producing hard carbon from lignocellulosic biomass has been the focus of recent studies as a promising source of anode material for Na-ion batteries. Woody biomass is a potential source, but it is already well valorised. Consequently, river driftwood can be an excellent alternative, especially since it is a disturbing waste for dam regulators. It c...

Many geomorphologists who are mothers find it challenging to balance field research alongside pregnancy and caring for young children. We offer perspectives on the challenges to conducting fieldwork as mothers and possible solutions, as a means of promoting conversations and highlighting issues that are less commonly considered in field‐based geomo...

In forested mountain catchment areas, both bedload and large wood (LW) can be transported during ordinary flows. Retention structures such as sediment traps or racks are built to mitigate potential hazards downstream. Up to now, the design of these retention structures focuses on either LW or bedload. In addition, the majority of LW retention racks...

In the last 30 years, work on large wood (LW) has expanded and matured considerably, and river scientists, managers and practitioners now have a better appreciation of the role of LW in maintaining ecosystems, forming or stabilising riverine landforms, and interacting with river morphodynamics. We have gained a better understanding of the hazards p...

Large wood (LW) accumulations can cause several damages, especially if the recruited wood is transported during floods down to urban areas, like Lourdes (France). One of the most serious problems concerning bridges and weirs all around the world, is the formation of LW accumulations, that might be responsible for the structure's failure. However, t...

2D numerical modelling indicated that backwater fluctuations of the Czorsztyn Reservoir increase floodwater depth (up to 255%) and decrease flow velocity (up to 72%) and bed shear stress (up to 80%) in the backwater zone of the mountainous Dunajec River. They also trigger further morphological changes, which additionally modify the initial river hy...

The cover image is based on the Original Article Reflections on the History of Research on Large Wood in Rivers by Frederick J. Swanson et al., https://doi.org/10.1002/esp.4814. The cover image depicts Large wood in Lookout Creek, H.J. Andrews Experimental Forest, western Cascade mountains, Oregon, USA, which is the location of studies of effects o...

Water-related problems affect several billion people’s lives and represent an annual challenge assessed at multitrillion US dollars, which substantiates their core role in the UN Sustainable Development Goals. Preventing direct and indirect impacts associated with water excess or water scarcity events requires expert judgement based on reliable inf...

Floods are caused by the interaction of several physical processes and factors including meteorological conditions, the soil moisture state of the catchment, the type of the dominant runoff generation processes, and river routing. Detailed knowledge of the synoptic-scale and meso-scale meteorological conditions leading to the triggering of flood-pr...

Upstream from a dam reservoir, river hydrodynamics may be directly changed by temporary inundation driven by the reservoir. This triggers morphological river changes which may additionally modify the initial hydrodynamics, even at the time when backwater inundation does not occur (indirect effects of backwater). We verified these hypotheses, applyi...

Lecture at the River University organized by the Coalition Clean Baltic (CCB): https://ccb.se/?event=river-university&event_date=2020-10-20 Video (live recording) available at: https://bit.ly/3m2D95l

Coarse particulate organic matter (CPOM, i.e., particles such as leaves, wood fragments, twigs, branches, flowers, seeds and fruits) in aquatic systems influences the flow, provides an important food source, and at the catchment scale, may significantly contribute to total carbon export. CPOM exports have rarely been quantified in subtropical, broa...

Keynote lecture at the 10th International Conference on Fluvial Hydraulics (River Flow 2020) When a tree falls in a river triggers a sequence of physical and ecological processes that can be defined as a process cascade. The interaction between flow, sediment and wood contributes to maintain and restore both the physical and ecological integrity o...

Large wood promotes fundamental changes in river hydraulics and morphology, playing a relevant role in river ecology but also in flood hazard. Accurate predictions of large wood dynamics in terms of deposition patterns and travel distance are still lacking and only recently have numerical models been developed to this end. In this work we enhance t...

The Flood Hazard and Risk Science has undergone a revolution over the last decade driven by the dramatically growing capabilities for monitoring and modelling Earth processes. Data are increasingly available from the extensive use of unmanned aerial vehicles equipped with diferent sensors, ground based imagery, the development of active remote-sens...

Explosive volcanic eruptions generate a range of physical processes with great hazard potential. Subsequent fluvial processes have major effects on channel and valley-floor geometry, potentially resulting in extreme sediment and large wood (LW) yields. The associated impacts can be severe, both immediately and in the longer term as river channels a...

Streamwood accumulation at bridges exerts additional forces to bridge structures and may aggravate flooding, local scouring, and eventually may lead to bridge collapse. However, the important ecological role of streamwood in fluvial systems calls for a compromise between preservation of river ecosystems and prevention of streamwood‐related hazards...

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 US in the early 20th century, but did not begin in earnest until the 1970s. Research has increased in in...

The overall goals of this report were (a) to synthesize the main results of flood change studies for Swiss rivers and place them in the context of flood changes in Europe and globally, (b) to describe the state-of-the-art methods used in flood change research and provide methodological guidance to readers, and (c) to systematically present and disc...

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....

Fluvial wood is recognized as one of the key elements of riverine environments. Its importance, role, and potential related risks are widely considered and analysed. Still, to characterize and measure wood elements in the field, a large investment in terms of time and cost is normally required. These activities are often carried out in complex and...

During the past three years the WoodFlow project (2015-2019, funded by the Federal Office for the Environment) aimed to develop the knowledge and methods to analyse instream large wood dynamics and to mitigate potential wood-related hazards in Swiss rivers. This paper presents part of the relevant results related to the analysis of the spatial and...

The natural wood regime forms the third leg of a tripod of physical processes that supports river science and management, along with the natural flow and sediment regimes. The wood regime consists of wood recruitment, transport, and storage in river corridors. Each of these components can be characterized in terms of magnitude, frequency, rate, tim...

Extreme precipitation events with high local precipitation intensities, heavy snowfall or extensive freezing rain can have devastating impacts on society and economy. Not only is the quantitative forecast of such events sometimes difficult and associated with large uncertainties, also are the potential consequences highly complex and challenging to...

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 (WLF) are not well understood yet. With the aim to shed light on these relatively unexamined phenomena, we collected home videos showing...

La mayor parte de los ríos de nuestro entorno, especialmente en Europa, están en mayor o menor medida alterados. Siglos de gestión de los ríos y sus cuencas han resultado en ríos con regímenes de caudales modificados, abundantes canalizaciones y estructuras hidráulicas que modifican su trazado natural, y escasa o nula vegetación de ribera. Como con...

On 24 July 2014, an exceptionally large flood (recurrence interval ca. 150 years) caused large-scale inundations, severe overbank sedimentation, and damage to infrastructure and buildings along the Emme River (central Switzerland). Widespread lateral bank erosion occurred along the river, thereby entraining sediment and large wood (LW) from alluvia...

The compound hazard effects of multiple process cascades severely affect Chilean river systems and result in a large variety of disturbances on their ecosystems and alterations of their hydromorphologic regimes leading to extreme impacts on society, environment and infrastructure. The acute, neo-tectonically pre-determined susceptibility to seismic...

Natural disasters are responsible for fatalities and economic losses worldwide, and among them, floods are the most widespread and cause the highest damages. A significant amount of the damages related to floods are caused by the associated geomorphic processes (e.g. bank erosion and channel widening). River response to floods can vary significantl...

Natural disasters are responsible for fatalities and economic losses worldwide, and among them, floods are the most widespread and cause the highest damages. A significant amount of the damages related to floods are caused by the associated geomorphic processes (e.g. bank erosion and channel widening). River response to floods can vary significantl...

Organic material (i.e., trees, branches, wood in general) is commonly neglected among the classical criteria to distinguish flow types, mostly due to the lack of direct observations of flows in which this load is significant. However, in forested basins, large amounts of wood can be transported. Here we define and characterize, for the first time,...

On July 24, 2014, an exceptionally large flood (recurrence interval ca. 150 years) caused large-scale inundations, severe overbank sedimentation and damage to infrastructures and buildings along the Emme river (central Switzerland). Widespread lateral bank erosion occurred along the river, thereby entraining sediment and large wood (LW) from alluvi...

Unmanned aerial vehicles provide a powerful approach to obtain high resolution aerial imagery. This information is used to analyse different aspects of the fluvial ecosystem. We present a method to measure and quantify fluvial wood deposits in rivers .

The quantification of large wood dynamics within river networks is crucial for managing rivers under contemporary human pressures, but still we need a better understanding of the factors controlling wood mobility, especially in large multithread rivers.

Physical and numerical modelling are powerful tools to understand wood dynamics. However, models that assume logs as cylinders, simplify the real shape of logs. This work aims to fill this gap adapting the Iber-Wood model to simulate logs with roots.

The identification of large organic matter (wood) recruitment processes and sources, and the prediction of potential wood delivery are key to support river basin planning and management, both from an ecological point of view and from a flood hazard and risk perspective.

En Espagne, où les bois morts tombés dans les cours d'eau ont été systématiquement retirés des rivières pendant des décennies, les gens sont habitués aux rivières avec peu ou pas de bois mort. Des études antérieures ont indiqué que la perception négative du bois en rivières est liée au manque de connaissances de base sur l'écologie des cours d'eau...

The effect of instream wood on stream hydraulics and geomorphic processes depends on wood and channel dimensions. We investigated abundance and characteristics (i.e., wood orientation, proportion of spanned channel width, stability and decay classes) of large wood (LW; defined here as having a length ≥1 m and a diameter ≥0.1 m) and small wood (SW;...

In-channel wood is a key component in fluvial ecosystems; however, transport of in-channel wood during floods can create hazards in urbanized areas. Among the main problems is wood accumulation at bridges, which reduces flow openings, causes blockage and inundation of nearby areas and, eventually, results in structures collapsing. Increasing awaren...

Understanding large wood (LW, ≥ 1 m long and ≥ 10 cm in diameter) dynamics in rivers is critical for many disciplines including those assessing flood hazard and risk. However, our understanding of wood entrainment and deposition is still limited, mainly because of the lack of long-term monitoring of wood related processes. The dataset presented her...

Instream large wood (LW) is widely perceived as a source of hazard that should be avoided. This is also the case of Spain, where wood has been systematically removed from rivers for decades. Consequently, people are accustomed to rivers with minimal or no LW at all. However, the presence and transport of wood is natural and has positive ecological...

Periglacial areas are shaped by very active geomorphic processes resulting in a highly dynamic landscape. In this context, the hillslope-channel coupling plays a fundamental role in controlling catchment sediment dynamics. The sediment produced on hillslopes may reach the channel network and downstream propagation may have important effects on the...

We analyzed instream wood depletion or breakdown in terms of wood breakage (defined as the reduction in length) and decay (reduction in diameter) on channel segments of three low-order mountain streams located in southern Chile. We used a unique database, composed of 1049 individually tagged logs, which were measured and their position was georefer...

Rivers do not only carry clear water during floods, in particular in mountain areas, significant volumes of sediment (both suspended and bedload inorganic sediment), and in forested basins, large amounts of organic sediment (i.e., instream wood) can be also entrained and transported. At critical sections such as bridges or narrow sections, the tran...

The assessment and mitigation of floods in mountain streams, when large wood (LW) is transported, pose several challenges. The process chain consisting of flood propagation, large wood recruitment, entrainment, transport and entrapment triggers, at critical sections such as bridges, unexpected and exacerbated impacts to the exposed built environmen...