Oscar Link

• Professor
• Professor (Full) at University of Concepción

This study presents an analysis of the convective storms occurring in the Atacama Region of Chile, which produce damaging floods in populated areas. These convective storms are rarely recorded with gauges due to their spatially bounded character, challenging traditional measuring methods and approaches for their analysis. Precipitation data gained...

Nature based solutions (NbS) for flood regulation (e.g., forest restoration) need to be informed by the analysis of climate change and land-use/cover change (LUCC) effects on floods, but these effects are still poorly understood. In this study, it is hypothesized that effects of climate change and LUCC on floods exhibit an abrupt change at a thresh...

Accurate numerical simulations of floods provide precise hazard estimations and can improve risk management strategies. Unfortunately, flood events of extraordinary magnitude -needed for risk assessment- are rare and difficult to measure. Hence, numerical models are typically calibrated and validated using a few measured scenarios of moderate magni...

Quantifying drought's economic impacts has been key for decision-making to build future strategies and improve the development and implementation of proactive plans. However, climate change is changing drought frequency, intensity, and durability. These changes imply modifications of their economic impact, as longer droughts result in greater cumul...

Bridges crossing rivers wider than 50 m are typically supported by piers. In a mobile riverbed, scour occurs around bridge piers, and it is the main cause of bridge collapses worldwide, especially during floods. While bridge pier scour has been extensively studied, there is still a lack of measuring systems for scour monitoring in the field. In thi...

The recurrent colonization of freshwater habitats and subsequent loss of diadromy is a major ecological transition that has been reported in many ancestrally diadromous fishes. Such residency is often accompanied by a loss of tolerance to seawater. The amphidromous Galaxias maculatus has repeatedly colonized freshwater streams with evidence that fr...

Concrete is one of the most widely used construction materials all around the globe. Associated with urban expansion, concrete pavements increase the impermeable surfaces that affect the hydrological cycle and generate urban heat islands. Cement is one of the main components of concrete, and its production is one of the main sources of worldwide CO...

Bridge failures due to scour occur more frequently than expected, although bridge design considers conservative scenarios, evidencing a stochastic scour behaviour and the need for improvements in current design procedures. In this paper, a new method for determination of design local scour depth at bridge piers is proposed. The results show that pe...

Bridge failures due to scour occur more frequently than expected, although bridge design considers conservative scenarios, evidencing a stochastic scour behaviour and the need for improvements in current design procedures. In this paper, a new method for determination of design local scour depth at bridge piers is proposed. The results show that pe...

Exact knowledge of the physical structures of different river sections that govern their ecological structure and function is essential for the efficient conservation and management of riverine ecosystems. Eleven Andean river basins (Maipo, Rapel, Mataquito, Maule, Itata, Biobío, Toltén, Valdivia, Bueno and Puelo) comprise large scale latitudinal a...

Native forest deforestation has been identified as one of the main land cover changes affecting flood risk specially during small and moderate storm events. In this regard, forest protection and reforestation are considered a nature-based solution (NbS) for flood regulation. However, there is a lack of knowledge about the effects of different defor...

Under a flow in supercritical regime, depending on the pier width to water depth ratio, the flow pattern around a bridge pier can take the form of a wall-jet-like bow wave or a detached hydraulic jump. The present work aims at analysing the maximum scour depth at piers in both flow patterns. A dedicated experimental set-up was used to produce the l...

Fluid Mechanics courses comprise both theoretical and laboratory modules. In developing nations, computer‐assisted techniques are not commonly applied in Fluid Mechanics instruction. Forced by the COVID‐19 pandemic, South American universities are, however, using them for online teaching. This contribution presents an 8‐semester (2016–2019) educati...

The new toolbox ScourApp is presented and applied for analysis of the complex interactions between local scour and sediment deposition at bridges during floods and to determine the relative importance of the controlling parameters on scour depth. ScourApp represents the time-dependent sediment transport processes through modern empirical formulatio...

Microplastics (MPs) have been recognized as as one of the most ubiquitous environmental pollutants globally. They have been found in all ecosystems studied to date, threatening biological diversity, ecosystem functioning and human health. The present study aimed to elucidate the environmental and anthropogenic drivers of MP dynamics in the whole ca...

Preparedness against floods in nearly pristine socio-hydrological systems The relations between preparedness and psycho-social attributes of people and communities exposed to river floods in a nearly pristine socio-hydrological system were investigated, applying hydrological-hydraulic analysis of flood risk in combination with results from a survey...

An experimental analysis of the dynamics of avalanches for different stages of development and turbulent flow conditions is introduced. Experiments were conducted in a laboratory flume using clear-water conditions and a video camera placed within an acrylic cylinder. The results of a proper orthogonal decomposition of the pre-processed image sequen...

ScourAPP es un software de código abierto que modela la evolución temporal de la socavación local ante condiciones hidráulicas complejas. El software es gratuito y puede ser descargado, usado y modificado por cualquier usuario. Tiene una interfaz gráfica y códigos que pueden emplearse con objetivos de diseño, simulación de escenarios y/o docencia u...

Description and characterization of bed forms in different environmental settings requires an assessment of three-dimensionality. This is related to the irregularity of the bed form shape and the degree of dissimilarity from strictly 2D bed forms, those bed forms that are straight, continuous, lack of defects and are arranged in groups with an alig...

Complete hydrological time series are crucial for water and energy resources management and modelling in a changing climate. The reliability of the non-parametric stochastic machine learning algorithm MissForest was assessed for gap-filling of daily streamflow time series in a data-scarce region with strong climatic variability. A total of 1,586 re...

Morphodynamic experiments are still essential for the prediction and prognosis of morphodynamic processes. But, scaling of sediment characteristics from nature to laboratory experiment are restricted and scaling laws recently propose a scaling of nature sieve curve to a uniform lightweight synthetic pellet. Thus, sieve curve properties from nature...

Bridge destruction occur under high flow intensities with sediment transport conditions. In a hydraulic flume with sediment recirculation, physical model tests were carried out on scour formation on bridge piers under clear-water conditions, during bedload transport and suspension load transport. Polystyrene granulate was used as sediment. Flow vel...

High mountain reservoirs receive sediments from sources located in watersheds with scarce vegetation cover, especially during highly erosive events. The sediments entering reservoirs in such regions, are typically composed by a mixture of gravels and sands and to a lesser portion silts and clays. The gravel is transported mainly as bed-load and for...

In Fließgewässern und in küstennahen Bereichen sowie Offshore werden Bauwerke gegründet, die der Strömung ausgesetzt sind. An der Bauwerksgründung kann es durch die Strömung zu lokalen Erosionen, den sogenannten Auskolkungen, kommen. Dabei wird im Bereich der Bauwerksgründung die Gewässersohle erodiert. Bei der Planung der Bauwerksgründung stellt s...

Estimation of the maximum scour depth is important for defining the size and depth of building foundations in order to avoid failure during a tsunami event (Jayaratne, et al 2016). Traditionally, tsunami scour has been studied in laboratory experiments that use solitary waves. However, it has been demonstrated that this type of wave does not repres...

Connectivity plays a crucial role in maintaining the structural and functional attributes of river networks. Therefore, the loss of connectivity (fragmentation) alters the functioning and diversity patterns of the biota at local and regional scales. The global hydropower boom is one of the main drivers of river network fragmentation, with significa...

En este estudio se analiza el efecto de la vegetación arbórea ribereña sobre la sedimentación en barras durante crecidas fluviales. Para ello, se realizó un estudio en el río Carampangue. Se caracterizó la vegetación ribereña. Se midió la sedimentación en 27 sitios con vegetación y 9 sin vegetación. Los resultados obtenidos muestran que la presenci...

Diadromy is known for having major effects on the distribution and richness of aquatic species, and so does its loss. The loss of diadromy has led to the diversification of many species, yet research focusing on understanding its molecular basis and consequences are limited. This is particularly true for amphidromous species despite being the most...

In recent decades, the role of vegetation on river morphodynamics become evident and in certain cases, riparian trees are recognized as a promising alternative for a more sustainable river management. In this study we analyse the interaction between riparian trees and sedimentation in a sandy river reach located in the central part of Chile. Introd...

Scour, which represents a fascinating and complex engineering problem involving a number of physical mechanisms and interactions, has motivated a vast amount of research following different but complementary methodological approaches such as experimental, numerical, and field methods. Far from being completely understood, scour remains one of the m...

Las pérdidas económicas de los desastres en las últimas décadas se han incrementado como resultado del desarrollo económico y probablemente con el aumento del número de eventos meteorológicos extremos (Haer, 2017). En tal sentido, los sistemas de alerta temprana son una herramienta para fortalecer los niveles de preparación vinculados a la gestión...

Massive exploitation of freshwater systems for hydropower generation in developing countries is challenging sustainability due to cumulative environmental impacts in regions with high endemism. Habitat fragmentation is recognized as a major impact on river ecosystems. The nature and magnitude of connectivity loss depend on characteristics of the hy...

The local scour and sediment deposition at a bridge pier during flood waves is analyzed to investigate the effects of different flow and sediment regimes (regulated and unregulated discharges with or without excess sediment supply). Concurrent field measurements of scour and streamflow were performed during six days at the Rapel Bridge, over the Ra...

Comprehensive flood risk assessment requires enhanced understanding of the coevolution of the river and its floodplain occupation. Paleoflood analysis to determine flood prone areas in combination with numerical simulations to estimate flood hazard and a historical analysis of urban development to consider the evolution of exposure to floods is a p...

The scour at bridge foundations caused by supercritical flows is reviewed and knowledge gaps are analyzed focusing on the flow and scour patterns, available measuring techniques for the laboratory and field, and physical and advanced numerical modeling techniques. Evidence suggests that the scour depth caused by supercritical flows is much smaller...

To achieve sustainable development of hydroelectric resources, it is necessary to understand their availability, variability, and the expected impacts of climate change. Current research has mainly focused on estimating hydropower potential or determining the optimal locations for hydropower projects without considering the variability and historic...

Hydroelectricity is the most widely used renewable electricity generation source worldwide. In Chile, about 29% of the installed capacity in the National Electric System corresponds to hydroelectric power. Hydroelectric plants are characterized by being a mature technology, with low investment and operating costs, as well as having conversion effic...

Background: Fragmentation (establishment of barriers e.g., hydropower dams, reservoirs for irrigation) is considered one of the greatest threats to conservation of river systems worldwide. In this paper we determine the fragmentation status of central Chilean river networks using two indices, namely Fragmentation Index (FI) and Longest Fragment (LF...

Inundaciones fluviales y anegamientos son procesos recurrentes en la comuna de San Pedro de la Paz, detonados principalmente por la ocurrencia de precipitaciones intensas. Las zonas de inundación fueron delimitadas mediante modelación hidráulica, mientras que las áreas susceptibles de presentar anegamientos fueron determinadas mediante 3 factores f...

Based on recent contributions regarding the treatment of unsteady hydraulic conditions in the state-of-the-art scour literature, theoretically derived probability distribution of bridge scour is introduced. The model has been derived assuming a rectangular hydrograph shape with a given duration, and a random flood peak, following a Gumbel distribut...

The magnitude of hydropower developments in emerging regions threatens the sustainability of their riverine landscapes. Fragmentation of river networks by multiple barriers and the imposition of new hydrological regimes influences the ability of these river ecosystems to absorb and adapt to these developments and other stressors. Direct transfer of...

Climate variability is one of the most determining elements in the availability of water. In Chile, the largest hydroelectric development is in the Biobío river basin. This study analyzes the relationship between temporal variability of streamflow and climate indices from the method of empirical mode decomposition and cross-correlation. It was foun...

Based on recent contributions regarding the treatment of unsteady hydraulic conditions into the state-of-the-art of scour literature, the theoretically derived probability distribution of bridge scour is introduced. The model is derived assuming a rectangular hydrograph shape with a given duration, and random flood peak following a Gumbel distribut...

The feasibility of physical modelling techniques for quantification of prototype bridge pier scour in reduced scale models is investigated through 17 ad-hoc designed experiments which were conducted in three flumes with different widths and depths, using three sediments, and two other materials of different size and density. Experiments covered cle...

Scour is responsible for the failure of many bridges worldwide. In many situations, the scour hole at the bridge foundations may result from the incremental erosion caused by successive floods of low-medium and high intensity. The accumulated scour caused by a series of floods may produce critical scour depth not attained during a single extraordin...

The construction of fishways for upstream and downstream connectivity is seen as the preferred mitigation measure for hydropower dams and other riverine barriers. Yet empirical evidence for effective design criteria for many species is not available. We therefore assembled a group of international fishway design experts and combined their knowledge...

Hydraulics, specifically the engineering related to river infrastructure, has had always to deal with issues as floods, erosion debilitating important civil infrastructure (bridges, etc.). In recent years it has been shown that there is predictive value for hydraulics in studying and analyzing these phenomena at a reduced scale. For this reason the...

Bedforms-ATM (Bed forms analysis toolkit for multiscale modeling) is a software designed to hierarchize and quantify the dimensionality of natural bed forms fields. It comprises four modular applications, namely: (1) wavelet analysis, (2) Hovmöller analysis, (3) multiscale discrimination, and (4) three-dimensionality analysis. Bedforms-ATM also pro...

Scales involved in bridge pier scour include the Reynolds number, the Froude number, and the ratio of the pier to the sediment diameter, among others. Consequently, it is not possible to achieve perfect similitude, and thus scale effects between model and prototype arise. In fact, these scale effects distort the scour estimations typically used in...

Hydropower is experiencing a development boom worldwide. However, at the same time, challenge sustainability, mainly due to synergistic effects of several projects in the species distribution area. What and how hydroelectric projects will affect species, depends on a number of attributes. We analysed Chilean freshwater species distributed over 10 m...

The goal of this paper is to introduce the first clear-water scour model based on both the informational entropy concept and the principle of maximum entropy, showing that a variational approach is ideal for describing erosional processes under complex situations. The proposed bridge–pier scour entropic (BRISENT) model is capable of reproducing the...

Longitudinal river fragmentation through physical barriers is a major issue for the conservation of aquatic species in regions with intense hydropower development, such as Chile. The construction of fishways is the main mitigation strategy for maintaining connectivity for fish but development of designs suitable for a broad range of species is chal...

Bridges are important for society because they allow social, cultural and economic connectivity. Flood events can compromise the safety of bridge piers up to the complete collapse. The Bridge Scour phenomena has been described by empirical formulae deduced from hydraulic laboratory experiments. The range of applicability of such models is restricte...

Bridges are important for society because they allow social, cultural and economic connectivity. Flood events can compromise the safety of bridge piers up to the complete collapse. The Bridge Scour phenomenon has been described by empirical formulae deduced from hydraulic laboratory experiments. The range of applicability of such models is restrict...

The pier scour caused by flood waves is analyzed, introducing the dimensionless effective work by the flow on the sediment bed around the pier, W*. The three-parameter exponential function is adopted to relate the normalized scour depth Z* with W*. A novel experimental installation able to reproduce any hydrograph with high precision in the laborat...

The time-dependent bridge pier scour during flood waves is analysed. Scour experiments were conducted in a novel installation able to produce complex hydrographs with high precision. Experimental data were used to test scour formulas including a new mathematical model. Results confirm the reliability and superior performance of the proposed dimensi...

A global level more than half of the water generated through the process of runoff is used by man. In south-central Chile the watersheds have been subjected to intensive processes of land use changes, including expansion of forest plantations with exotic species. This study evaluates the hydrological effects of future scenarios for forest expansion...

El fenómeno de socavación local es analizado bajo condiciones hidráulicas estacionarias y no estacionarias a escala de laboratorio. Series experimentales de literatura fueron consideradas en el análisis, donde parte de los ensayos no estacionarios fueron realizados en una instalación experimental capaz de reproducir ondas de crecidas fluviales con...

Hydropower barriers are among the most conspicuous anthropogenic alterations to natural riverine connectivity, resulting in species-specific effects linked to dispersal abilities, especially swimming performance. They may present a particular problem for small-bodied 'non-sport fish', such as those that characterize the freshwater communities of te...

The decline of freshwater fish biodiversity is proceeding at an alarming and persistent rate. Given that most fish must undertake some form of migration in order to complete their life-cycle, of particular concern is the proliferation of hydropower schemes that block migration routes, as well as a variety of other barriers such as weirs and culvert...

Hydrodynamics;Turbulence;Sediment transport;Rivers

Experiments on scour at bridge piers were carried out in a sediment recirculating flume with a bed of polystyrene particles. The focus of the research reported in this paper was given to live-bed experiments. All experiments were run until equilibrium conditions with flow velocities u ranging from 0.8–8.5 times the critical velocity for the incipie...

The mesoscale (10⁰–10² m) of river habitats has been identified as the scale that simultaneously offers insights into ecological structure and falls within the practical bounds of river management. Mesoscale habitat (mesohabitat) classifications for relatively large rivers, however, are underdeveloped compared with those produced for smaller stream...

The finite volumes method is applied to solve 2D Saint Venant equations with source terms that determine runoff of shallow water, in order to calculate flows caused by dam breaks. The model is verified by calculating six cases with known solutions: (1) establishing normal flow based on a horizontal free surface; (2) establishing flow that is gradua...

The finite volumes method is applied to solve 2D Saint Venant equations with source terms that determine runoff of shallow water, in order to calculate flows caused by dam breaks. The model is verified by calculating six cases with known solutions: (1) establishing normal flow based on a horizontal free surface; (2) establishing flow that is gradua...

Most artificial fish passes have been developed in Northern temperate rivers and are designed to serve large, migratory sport fish species (mostly salmonids). Experience in construction and maintenance of fish passes show that salmon-criteria are not adequate for flat-land rivers and non-sport fishes. Consequently, over the last decade, design crit...

Bedforms in alluvial river beds can often be identified as 2D- or 3D-forms. A complete description of bedforms, and even a full description of the riverbed topography, should distinguish between 2D and 3D bedforms; nonetheless, an objective and general method to assess bedform 3-dimensionality is not available. The paper presents a method for a mea...

Scour at piers embedded in a bed of cohesive sediment mixture is investigated to quantify the effects of bed compaction. Experiments were conducted in a large rectangular laboratory flume with natural clay sediment collected from a stream located at the Chilean coastal range. Non-intrusive and high-resolution topographic measurements of scoured bed...

The diel variation of temperature in mesoscale river reaches (catchment area > 1000 km2) is analysed using concurrent measurements of water temperature and of those meteorological (incident short-wave radiation, air temperature, relative humidity and wind speed variables) and hydraulic variables (streamflow, top width, channel slope and flow depth)...

Despite of the importance of temperature in the fluvial ecosystems, the knowledge of its spatial and temporal variability in Andean rivers is limited, thus it is necessary to clarify the relative importance of site-specific factors in controlling the temperature of rivers. The aim of this research was to characterize the thermal regime of five Ande...

Experimental results on the nature-like fishway induced flow field and its relation to fish behaviour are presented. A rocky-ramp with 5% slope was built along a 8.9 m × 0.9 m × 0.6 m laboratory flume, and acoustic Doppler velocity measurements were taken in a grid with 186 points for low, middle, and high discharges. The flow is characterized appl...

Thermal behavior of Mediterranean Andean streams in South-Central Chile Despite of the importance of temperature in the fluvial ecosystems, the knowledge of the spatial and temporal variability in Andean rivers is limited being necessary to clarify the relative importance of site-specific factors in controlling the temperature of rivers. The aim of...

Galaxias platei is the most broadly distributed fish specie in the Chilean Patagonia that inhabits in rivers and mainly in lakes systems. It occurs on varied habitats from clay platforms to thin substrates with presence of macrophytes, large woody debris and big boulders substrata. In this work we experimentally analyzed the microhabitat use of G....

Recent investigations on the dynamics of the turbulent horseshoe vortex system (THV) around cylindrical piers have shown that the rich coherent dynamics of the vortical structures is dominated by low-frequency bimodal fluctuations of the velocity field. In spite of these advances, many questions remain regarding the changes of the flow and sediment...

Galaxias platei is the most broadly distributed fish specie in the Chilean Patagonia that inhabits in rivers and mainly in lakes systems. It occurs on varied habitats from clay platforms to thin substrates with presence of macrophytes, large woody debris and big boulders substrata. In this work we experimentally analyzed the microhabitat use of G....

The finite volumes method is applied and the ultimate strategy is generalized to solve the advection-diffusion-reaction equation with variable parameters, in order to obtain results with negligible numeric diffusion. The model is verified through calculations with known analytical solutions, showing its capability to simulate diffusive and advectiv...

The finite volumes method is applied and the ultimate strategy is generalized to solve the advection-diffusion-reaction equation with variable parameters, in order to obtain results with negligible numeric diffusion. The model is verified through calculations with known analytical solutions, showing its capability to simulate diffusive and advectiv...

The manuscript refl ects the opinion of the authors about the need for a hydromorphological approach for the management of Chilean rivers. A brief state-of-the-art of the recent scientifi c advances on hydromorphological approach to river management is presented, as well as a general overview of the conditions of Chilean rivers and the mayor distur...

The manuscript reflects the opinion of the authors about the need for a hydromorphological approach for the management of Chilean rivers. A brief state-of-the-art of the recent scientific advances on hydromorphological approach to river management is presented, as well as a general overview of the conditions of Chilean rivers and the mayor disturba...