Andrés Iroumé

• Doctor of Forest Sciences
• Professor (Full) at Universidad Austral de Chile

Wood is crucial in river systems, influencing both ecological and physical dynamics. Understanding its behaviour in relation to fluvial morphology is essential for effective watershed management, especially after extreme events. The tendency of wood to accumulate into wood jams (WJs) adds complexity, as these dynamics remain challenging to assess....

Chaitén, a city in Chilean Patagonia, was hit by lahar flows from the Blanco River in May 2008 following a massive volcanic eruption. This cascade process resulted in the avulsion of the active channel of the Blanco River, dividing the city into two sectors, destroying built environments, and causing displacement of the local population. Hydrodynam...

Forestry operations and climate variability affect hydrologic response and sediment transport. Management of forested catchments under intense forestry activity in areas under climatic stress is critical. This study analyzes the impact of forest operations (thinning and clearcutting) on runoff (Q) and suspended sediment loads (SSL) in three small c...

The coastal temperate rainforests (CTRs) of Chilean Patagonia are a valuable forest biome on Earth given their prominent role in biogeochemical cycling and the ecological value and dynamics of surface processes. The Patagonian CTRs are amongst the most carbon-rich biomes on Earth. Together with frequent landscape disturbances, these forests potenti...

Data collected between 2015 and 2022 was utilised to assess longitudinal connectivity and explain the temporal and spatial fluctuation of large wood (LW) along the Blanco River, which was severely affected by the 2008 eruption of the Chaitén Volcano in southern Chile. The study was performed along a ~ 10.6-km long segment, which was divided into tw...

Large wood (LW, wood pieces with diameter ≥ 10 cm and length ≥ 1 m) is present in rivers as individual elements or forming accumulations. During the 1970s, the study of LW in rivers began to be massified in the USA, mainly in the assessment of its effect on fish (Swanson et al., Earth Surface Processes and Landforms 46:55–66, 2021). It is essential...

Chile is frequently affected by different natural hazards that are constantly reshaping the landscape. Particularly, Large and Infrequent Disturbances (LIDs) such as wildfires and volcanic eruptions are capable of affecting entire river catchments by altering the hydrological cycle, reducing the land cover, and boosting sediment remobilization. Giv...

The eruption of the Calbuco volcano on April 22, 2015 presented three eruptive pulses, the second eruptive pulse being the main responsible for the most considerable impacts both in the natural and anthropic environment. This pulse generated several lahars due to the interaction of pyroclastic flows with glaciers and snow close to the summit of the...

Gravel-bed rivers are fluvial systems featuring highly complex morphological and evolutionary patterns because of their configuration characterized by the contemporary presence of many distinct morphological units. Complexity can also be observed in the response of gravel-bed rivers to flow conditions, which can be highly varied. This work aims to...

The Coastal Temperate Rainforests (CTRs) of Chilean Patagonia are a valuable forest biome on Earth given its prominent role for biogeochemical cycling, ecological value and dynamic of surface processes. The Patagonian CTRs are amongst 20 the most carbon rich biomes on Earth. Together with frequent landscape disturbances, these forests potentially a...

Volcanic eruptions can disrupt entire river basins by affecting the hydro-geomorphic characteristics of channel networks and hillslopes. Reports suggest a pulsed and delayed increase in landslide activity following the eruptions, which, depending on the degree of linkage between hillslopes and channels, i.e. sediment connectivity, can represent a m...

Volcanic eruptions can dramatically alter river basins and channel networks by delivering huge amounts of sediments into the channels and affecting the surrounding vegetated area. These disturbances modify the process chain of large wood (LW) recruitment, storage, and transport. We investigated the effects of the 2015 Calbuco volcanic eruption in s...

This paper reviews the current knowledge of hydrological processes in Chilean temperate forests which extend along western South America from latitude 29° S to 56° S. This geographic region includes a diverse range of natural and planted forests and a broad sweep of vegetation, edaphic, topographic, geologic, and climatic settings which create a un...

The effect of Eucalyptus plantations on water balance is thought to be more severe than for commercial alternatives such as Pinus species. Although this perception is firmly entrenched, even in the scientific community, only four direct comparisons of the effect on the water balance of a Eucalyptus species and a commercial alternative have been pub...

Large wood (LW, log at least 1 m-long and 0.1 m in diameter) in river channels has great relevance in fluvial environments. Historically, the most used approach to estimate the volume of LW has been through field surveys, measuring all the pieces of wood, both as single elements and those forming accumulation. Lately, the use of aerial photographs...

The effect of Eucalyptus plantations on water balance is thought to be more severe than for commercial alternatives such as Pinus species. Although this perception is firmly entrenched, even in the scientific community, only four direct comparisons of the effect on the water balance of a Eucalyptus species and a commercial alternative have been pub...

Study region Eight rivers regulated by large dams located in three hydro-climatic zones along the Chilean latitudinal gradient. Study focus We performed a multi-temporal scale analysis of flow records and we used data from official gauging stations to characterise the non-altered and the altered river regimes to determine the magnitude and persist...

Land cover change and its effect on water resources has been a continuous concern in south-central Chile. In this regard, we use two methodologies to study the effect of different land covers on the hydrological processes in several experimental catchments (<100km2) located between 36°S to 39°S. These experimental catchments include native forest a...

An extensive programme of commercial afforestation in south‐central Chile provides a unique opportunity to extend the field‐based understanding of forest impact on floods to the large catchment scale (100‐1000 km2). Until now, much of that understanding has been limited to small catchments (< 10 km2). Data for an approximately 50‐year period are an...

Sudden avulsions, unexpected channel migrations and backfilling phenomena are autogenic phenomena that can considerably change the propagation patterns of sediment-laden flows on alluvial fans. Once the initial and boundary conditions of the hazard scenario with a given return period are determined, the assessment of the associated exposed areas is...

We analyzed the abundance of benthic algae in nine forested headwater watersheds in south-central Chile to study the relationship between the variability of the abundance of benthic algae and physicochemical parameters and forest cover factors. Between 10 November 2015 and 18 August 2016, we sampled benthic algae and physicochemical parameters in t...

There are more than 4 billion hectares of forests in the world, which corresponds to 31 % of the surface of our planet. In Chile, 17 million ha of forests cover the country where more than 3 million correspond to plantations. The role of vegetation cover in the dynamics of precipitation, in the generation of runoff and in the protection and conserv...

We studied the recovery of the woody vegetation in a segment of the Rayas River, that drains the Chaitén Volcano, in southern Chile. Data collection in the river corridor was performed to assess the regeneration rates of the colonizing vegetation within the river corridor, to investigate the site-specific regeneration modes (i.e., with respect to t...

Autogenic processes, such as sudden avulsions, unexpected channel migrations and backfilling phenomena, can considerably alter the propagation of sediment-laden flows on alluvial fans. Once the initial and boundary conditions of the hazard scenario with a given return period are determined, the delineation of the associated exposed areas is based o...

Few long-term studies have explored how intensively managed short rotation forest plantations interact with climate variability. We examine how prolonged severe drought and forest operations affect runoff in eleven experimental catchments on private corporate forest land near Nacimiento in south central Chile over the period 2008 to 2019. The catch...

In central Chile, many communities rely on water obtained from small catchments in the coastal mountains. Water security for these communities is most vulnerable during the summer dry season and, from 2010 to 2017, rainfall during the dry season was between 20% and 40% below the long‐term average. The rate of decrease in stream flow after a rainfal...

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...

Fingerprinting techniques were incorporated into a paired catchment investigation in southern Chile to quantify the contribution of three fine sediment sources (catchment surfaces, forest roads and stream channels) to catchment suspended sediment yields during forest harvesting and replanting operations. Optimum composite fingerprints for use in se...

The importance of monitoring and analysing wood fluxes in mountain environments is widely recognized. However, there is a lack of information related to the long-term fluctuations in wood load and associated to the changes in large wood (LW) characteristics. The main aims of the research were to analyse (i) changes in wood characteristics, (ii) flu...

Wildfires are able to kill large amounts of trees that can be recruited into the drainage network. Contrary to other large disturbances, most of these woody elements can be classified as "potential LW" since they are not necessarily recruited into the channels during or immediately after the disturbance. Our research deals with this topic, improvin...

Gravel-bed rivers exhibit remarkable dynamics and distinctive morphological patterns which influence the biological processes, as well as the river ecosystem resilience to human impacts. Classifications of river ecosystems into groups with morphologically distinct patterns are therefore of paramount importance for a better understanding of their dy...

In this study, we analysed the morphological evolution of a channel segment in the Blanco River in southern Chile that was affected by the Chaitén Volcano eruption occurred in 2008–2009. Through a series of high-resolution satellite images from 2005 to 2019 that represents the entire pre- and post-eruptive dynamics and land covers, we tracked the g...

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...

This study analyses the changes in the runoff of forested experimental catchments in south-central Chile, to determine to what extent observed trends can be attributed to effects of intensive forestry and/or climate change. For this, we applied the distributed TETIS® model to eight catchments (7.1−413.6 ha) representative of the land uses and fores...

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...

The extent to which forests, relative to shorter vegetation, mitigate flood peak discharges remains controversial and relatively poorly researched, with only a few significant field studies. Considering the effect purely of change of vegetation cover, peak flow magnitude comparisons for paired catchments have suggested that forests do not mitigate...

Chilean territory is recurrently affected by severe wildfires, which drastically reduce the forest cover and promote runoff, soil erosion and slope instabilities. To understand how the geomorphic system responds to wildfires in terms of sediment dynamics, the assessment of sediment connectivity, i.e. the property describing the relationships betwee...

Wildfire-related impacts on the hydrogeomorphic properties of river basins is scarcely studied in South American sites. Fire affects river systems by altering the forest cover, decreasing the soil infiltration capacity, modifying the sediment yields and leading to channel instability. To study the effect of the disturbance in the sediment routing,...

The eco‐hydro‐geomorphic significance of large wood (LW) and its potential for increasing downstream hazards during extreme floods have been widely recognised. We used LW data collected for 10‐year period from the two low‐order streams of Pichún (Pi) and Vuelta de Zorra (VZ) in Southern Chile, to a) determine if the abundance and dimensions of indi...

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...

Sustainable Development Goals: Their Impacts on Forests and People - edited by Pia Katila December 2019

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...

River systems are continuously affected by multiple natural and anthropogenic phenomena. Among major natural disturbances, volcanic eruptions have the capability to overthrow the forms and to modify dramatically the morphological setting and sediment connectivity of the system. Moreover, the input of sediments in the channel network can lead to act...

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...

Our work analyses the intra‐annual variability of the volume of water stored in fifteen forested headwater catchments from south‐central Chile, aiming at understanding how forest management, hydrology, and climate influence the dynamic components of catchment storage. Thus, we address the following questions: (i) How does the annual water storage v...

The paired watershed approach is the most popular tool for quantifying the effects of forest watershed management on water sustainability. But this approach does not often address the critical factor of water stored in the landscape. Future work needs to quantify storage in paired watershed studies to inform sustainable water management.

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 .

We propose a quantitative approach to quantify large wood budget in highly disturbed stream channels. This approach accounts for changes in channel geometry and additional recruitment processes which characterise streams affected by volcanic eruptions.

This work aims at analysing variations in sediment connectivity induced by geomorphological changes in a Chilean volcanicimpacted environment. To this end a multitemporal analysis has been carried out.

Temporal variation of wood dynamic was investigated in the Blanco Este River, a Chilean watercourse affected by volcanic eruption. This preliminary study shows strong differences in LW abundance from

Characterizing river corridors from a hydro-morphological standpoint is a fundamental requisite for the analysis of their past evolution and for the plausible prediction of how rivers may adjust to changing climatic conditions and to increasing human impacts. The River Baker (Chilean Patagonia) is a highly dynamic fluvial system with relatively lim...

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...

In this paper we analyse the recent geomorphological evolution of the River Ñuble, an unmodified wandering river in the Mediterranean region of Chile, highlighting the relation between the observed hydroclimatic trends in the region and the morphology of the river. The work documents the recent changes (2003–2016) in channel morphology (i.e., narro...

Two recent studies help to define the extent to which forest cover, compared with a cover of shorter vegetation, can reduce flood peaks and sediment yields at the catchment scale as part of an integrated flood control programme. First, field data analysis and model analysis tested the hypothesis that, as the size of the rainfall event increases, th...

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...

Fjords and old-growth forests store large amounts of organic carbon. Yet the role of episodic disturbances, particularly volcanic eruptions, in mobilizing organic carbon in fjord landscapes covered by temperate rainforests remains poorly quantified. To this end, we estimated how much wood and soils were flushed to nearby fjords following the 2008 e...

The aim of this study is to analyze the temporal variation in abundance and transport of in-channel wood along a river affected by a volcanic eruption, considering the mobility and retention rates in detail. The 2008 eruption of Chaitén Volcano (Southern Chile) severely affected the Blanco River basin, causing changes in channel morphology and larg...

Alluvial fans are privileged settlement areas in many mountain regions of the world. From a geomorphological perspective, however, these landforms are particularly dynamic being episodically affected by distributary processes generated by extreme flood events. The accurate quantification, both with respect to space and time, of the exposure to such...

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...

River managers are aware that river restoration entails addressing and effectively solving wicked social-ecological problems. Contemporary river corridor management is characterized by a variety of actors with different perspectives and interests, and by complex institutional settings and legal landscapes. Additionally, at the intersection between...

Trees have been around for more than 370 million years, and today there are about 80 thousand species of them, occupying 3.5 billion hectares worldwide, including 250 million ha of commercial plantations. While forests can provide tremendous environmental, social, and economic benefits to nations, they also affect the hydrologic cycle in different...

Natural disasters can strongly and rapidly affect a wide array of environments. Among these, volcanic eruptions can exert severe impacts on the dynamic equilibrium of riverine environment. The production and subsequent mobilization of large amounts of sediment all over the river basin, can strongly affect both hydrology and sediment and large wood...

Trees have been around for more than 370 million years, and today there are about 80 thousand species of them, occupying 3.5 billion hectares worldwide, including 250 million ha of commercial plantations. While forests can provide tremendous environmental, social, and economic benefits to nations, they also affect the hydrologic cycle in different...

Hazards assessments at explosive volcanoes commonly focus on primary phenomena such as debris avalanches, pyroclastic density currents, lahars, and airfall tephra. Although primary processes can be devastating and far reaching, secondary hydrologic and geomorphic (hydrogeomorphic) processes to eruptions-such as flooding; sediment redistribution; an...

South America is experiencing rapid change in forest cover, of both native and planted forest. Forest cover loss is primarily attributable to fire, logging, and conversion of native forest to agriculture, pasture, and forest plantations, and types of change vary within and among the many diverse types of forests in South America. Major changes in f...

Dead trees in rivers can significantly affect their morphological and ecological properties by increasing flow resistance, affecting sediment transport, and storing organic matter. Logs are usually recruited from banks or along the entire upstream basin. Although it is generally acknowledged that forested headwater streams feature higher volumes of...

The 10 day explosive phase of the 2008-2009 eruption of Chaitén volcano, Chile, draped adjacent watersheds with a few cm to >1 m of tephra. Subsequent lava-dome collapses generated pyroclastic flows that delivered additional sediment. During the waning phase of explosive activity, modest rainfall triggered an extraordinary sediment flush which swif...

After several years of decreased annual rainfall and water shortages, the Chilean society is demanding that forest plantations take accountability of their role in consuming scarce water resources. Evidence has shown that interception losses are considerable when determining water production in watersheds. The aim of this study was to determine if...

To date, the study of in-stream wood in rivers has been focused mainly on quantifying wood pieces deposited above the ground. However, in some particular river systems, the presence of buried dead wood can also represent an important component of wood recruitment and budgeting dynamics. This is the case of the Blanco River (Southern Chile) severely...

Wood in riverine environments exerts different functions on ecological and geomorphic settings, influencing morphological processes, and increasing risks for sensitive structures. Large wood (LW) is defined as wood material, dead or alive, larger than 10 cm in diameter and 1 m in length. Natural hazards can strongly increase the presence of LW in w...

The calculation of differences between subsequent DEMs (difference of DEMs, DoD) is a commonly applied method to analyze and quantify morphological changes occurred along a riverine environment. The higher levels of uncertainty in the DoD computation are, typically, localized in area with low point density, steepest slopes and highest roughness val...

Volcanic explosive activity can strongly affect the riverine environments. Deposition of tephra, pyroclastic and hyperconcentrated flows along both the valley bottom and hillslopes can radically change the environmental morphology. Accumulation and transport of pyroclastic material can increase hazards and risks for anthropic activities. The aims o...

Bedload transport assessment is important for geomorphological, engineering, and ecological studies of gravel-bed rivers. Bedload can be monitored at experimental stations that require expensive maintenance or by using portable traps, which allows measuring instantaneous transport rates but at a single point and at high costs and operational risks....

The 2008 eruption of Chaitén volcano in southern Chile severely impacted several densely forested river catchments by supplying excess pyroclastic sediment to the channel networks. Our aim is to substantiate whether and howchannel geometry and forest stands changed in the Rayas River following the sudden input of pyroclastic sediment. We measured t...

The processes associated with the 2008 eruption of the Chaitén Volcano (south of Chile) generated morphological, ecological, and social disturbances. These disturbances were changes in the channel widths, vegetated islands and riparian forests. Changes in the river systems continued to occur years after the eruption due to hydrological processes in...

The 2008 Chaitén volcanic eruption generated significant changes in the channel morphology and large wood (LW) abundance along the fluvial corridor of the Blanco River, southern Chile. Comparisons of remote sensing images from the pre-eruption (year 2005) and post-eruption (years 2009 and 2012) conditions showed that in a 10.2 km long study segment...

Previous research on large wood (LW) entrainment and mobility has shown that in small rivers most mobile pieces are shorter and thinner than bankfull width and depth, and are deposited perpendicular or oblique to the flow as individual pieces. LW size, quantity and position were investigated over several years in channel segments of four mountain e...

The ecologic influence of in-stream large wood (LW) was evaluated at reach scale in a third-order channel located in the Coastal Mountain Range, southern Chile. The tested hypotheses were that Coarse Particle Organic Matter (CPOM) retention is higher and benthic macro-invertebrates are more diverse in channel reaches storing higher volumes of LW. T...

The ecologic influence of in-stream large wood (LW) was evaluated at reach scale in a third-order channel located in the Coastal Mountain Range, southern Chile. The tested hypotheses were that Coarse Particle Organic Matter (CPOM) retention is higher and benthic macro-invertebrates are more diverse in channel reaches storing higher volumes of LW. T...

Published data for temperate forests across the world are analyzed to investigate the potential for generalized quantitative expressions of catchment sediment yield impact in the years immediately following logging. Such generalizations would be useful in a variety of forestry and engineering tasks and would aid the spread of knowledge amongst both...

Volcanic eruptions drastically affect fluvial systems, modifying channel morphology and processes of supply and transport of sediment and wood material, destroying vegetation and reducing infiltration rates on hillsides. This work aims to study the morphological changes and the distribution of large wood (LW) material along the Blanco River after t...