Tracking swimming Lefua echigonia to assess the impact of crayfish introduction

Lefua echigonia is an endangered freshwater species in Japan, whose habitats are decreasing due to urbanization and modernization of agriculture. In addition, invasion by non-native crayfish, Procambarus clarkii, is known to be a threat to L. echigonia. Whereas we observed P. clarkii at L. echigonia habitats such as large gravels, little is known about the impact of P. clarkii invasions on L. echigonia. In this study, we conducted a laboratory experiment using a 25-cm cylinder to observe swimming behaviour of L. echigonia with varying number of P. clarkii individuals and the presence/absence of a rectangular obstacle at the center. Swimming trajectories were obtained from a series of images taken 30 frames per second, based on which swimming speed, acceleration, and distance between individuals were calculated for the assessment of behavioural changes with P. clarkii introduction. No feed was given for both species during experiment. While both species moved along the wall during experiment under no obstacle condition, L. echigonia was more active than P. clarkia. Behavioural changes were observed when the obstacle was placed in the center. Foraging by P. clarkii was expected but no such a behaviour was observed even under the condition where more P. clarkii individuals were put together. Whereas no foraging behaviour was observed, some L. echigonia individuals stayed around the brick which is similar to P. clarkia. This suggests potential habitat overlaps between the two species. Further study can reveal species competition under more complex, dynamic instream conditions for which image analysis with high-speed/high-resolution cameras can be used as a tool for reliable assessment

Computer vision applications using multispectral UAS imagery: comparing pixel and object-based methods for automatic classification of river landscapes

The use of unmanned aerial system (UAS) imagery in environmental sciences has rapidly increased due to the ease of use and low cost [1]. In general, the ecological informatics community widely uses spatial data analyses, especially via GIS. A growing number of applications now include UAS imagery, which can provide centimetre scale multispectral data [2]. Processing this information requires the application of image-based remote sensing techniques. Specifically, the differences between unsupervised and supervised image classification methods are discussed, with a focus on pixel and object-based computational methods [3]. Examples relevant to ecological studies are presented using multispectral imagery collected of river landscapes to illustrate how UAS data can be used to classify complex spatial features such as vegetation and submerged regions of different depths, including turbulent flows and complex lighting and shade conditions. REFERENCES: 1. Arif, M.S.M., Gülch, E., Tuhtan, J.A., Thumser, P., Haas, C., 2016. An investigation of image processing techniques for substrate classification based on dominant grain size using RGB images from UAV. Int. J. Remote Sens. 0, 1–23. https://doi.org/10.1080/01431161.2016.1249309 2. Hugenholtz, C.H., Whitehead, K., Brown, O.W., Barchyn, T.E., Moorman, B.J., LeClair, A., Riddell, K., Hamilton, T., 2013. Geomorphological mapping with a small unmanned aircraft system (sUAS): Feature detection and accuracy assessment of a photogrammetrically-derived digital terrain model. Geomorphology 194, 16–24. https://doi.org/10.1016/j.geomorph.2013.03.023 3. Black, M., Carbonneau, P., Church, M., Warburton, J., 2014. Mapping sub-pixel fluvial grain sizes with hyperspatial imagery. Sedimentology 61, 691–711. https://doi.org/10.1111/sed.1207

Numerische Untersuchungen des Turbinendurchganges von Fischen

Aufsatz veröffentlicht in: "Wasserbau-Symposium 2021: Wasserbau in Zeiten von Energiewende, Gewässerschutz und Klimawandel, Zurich, Switzerland, September 15-17, 2021, Band 2" veröffentlicht unter: https://doi.org/10.3929/ethz-b-00049975

Digitalization and real-time control to mitigate environmental impacts along rivers: Focus on artificial barriers, hydropower systems and European priorities

Hydropower globally represents the main source of renewable energy, and provides several benefits, e.g., water storage and flexibility; on the other hand, it may cause significant impacts on the environment. Hence sustainable hydropower needs to achieve a balance between electricity generation, impacts on ecosystems and benefits on society, supporting the achievement of the Green Deal targets. The implementation of digital, information, communication and control (DICC) technologies is emerging as an effective strategy to support such a trade-off, especially in the European Union (EU), fostering both the green and the digital transitions. In this study, we show how DICC can foster the environmental integration of hydropower into the Earth spheres, with focus on the hydrosphere (e.g., on water quality and quantity, hydropeaking mitigation, environmental flow control), biosphere (e.g., improvement of riparian vegetation, fish habitat and migration), atmosphere (reduction of methane emissions and evaporation from reservoirs), lithosphere (better sediment management, reduction of seepages), and on the anthroposphere (e.g., reduction of pollution associated to combined sewer overflows, chemicals, plastics and microplastics). With reference to the abovementioned Earth spheres, the main DICC applications, case studies, challenges, Technology Readiness Level (TRL), benefits and limitations, and transversal benefits for energy generation and predictive Operation and Maintenance (O&M), are discussed. The priorities for the European Union are highlighted. Although the paper focuses primarly on hydropower, analogous considerations are valid for any artificial barrier, water reservoir and civil structure which interferes with freshwater systems.Digitalization and real-time control to mitigate environmental impacts along rivers: Focus on artificial barriers, hydropower systems and European prioritiespublishedVersio

Ein Modellierungsansatz für Schwall und Sunk beeinflusste Fließgewässer unter Berücksichtigung des zweiten Hauptsatzes

An outcome of daily electrical energy consumption is that storage hydropower releases must match the changes in daily demand. These local, high intensity fluctuations are commonly called hydropeaking. Due to their large departure from natural flow rates, the river ecosystems downstream of hydro operations are forced to react. This causes a large shift in the dissipative regime of the river, affecting the entire food web from Sparganium emersum to Salmo trutta. Although the cause of hydropeaking in alpine rivers is obvious, assessing its ecological effects is not an easy task. The study of hydropeaking impacts on river ecology demands a great deal of new theoretical and phenomenological investigation. Complicating such studies is the fact that river ecosystems themselves are not stable systems but are evolving over time, even under steady flow conditions. Although ecological models of aquatic ecosystems have been present for several decades, it is currently not possible to model a fish’s response to the short-term fluctuations in the flow field caused by hydropeaking with the same degree of accuracy which has been achieved under steady flow conditions. The use of numerical models to assess the impacts of hydropeaking on aquatic ecosystems is still in its infancy. The challenge of this dissertation is to construct a theoretical framework that can be used to study abiotic-biotic interactions under highly unsteady conditions. The model is constructed through the lens of thermodynamics, by looking at system interactions in terms of the contributions of the relative equilibrium states: mechanical, chemical, and thermal. The objectives of this dissertation are: 1. Incorporate thermodynamic principles into an aquatic habitat model which can be effectively applied for highly unsteady flow regimes. 2. Evaluate the model in terms of performance, ease of application and theory. This work proposes a new kind of fish habitat model using thermodynamic concepts for use in European alpine rivers affected by hydropeaking. Ecosystem states may be found which allow for optimal systems in which animate components such as fish are able to participate. Furthermore, we show that a ‘first law’ approach which invokes only the conservation of energy is not sufficient to understand the energetics of the alpine river ecosystem. It is necessary to view the ecosystem in terms of its free energy and its entropy as well. This ‘second law’ methodology provides powerful insight and results in a more objective modeling approach to assess hydropeaking impacts on fish considering real-world conditions.Die Wasserabgabe von Speicherwasserkraftwerken zur Stromerzeugung muss an den Stromverbrauch angepasst werden, der im Laufe eines Tages starken Schwankungen ausgesetzt ist. Der daraus folgende Betrieb mit stark schwankender Wasserabgabe wird als Schwallbetrieb (Schwall-Sunk-Betrieb) bezeichnet. Wegen der hohen Unterschiede des Abflusses im Schwallbetrieb im Vergleich mit natürlichen Abflussmengen und Abflussschwankungen müssen sich unterstromige Ökosysteme an die neuen Bedingungen anpassen. Die gesamten Auswirkungen des Schwallbetriebs von Speicherwasserkraftwerken auf unterstrom liegende Ökosysteme zu quantifizieren ist jedoch keine einfache Aufgabe. Zur Beurteilung der gewässerökologischen Auswirkungen müssen eine Vielzahl von theoretischen und phänomenologischen Untersuchungen durchgeführt werden. Erschwert werden diese Untersuchungen durch die Fließgewässerökosysteme selbst, da diese keine stabilen Systeme darstellen, sondern sich fortgehend verändern, sogar unter stationären Strömungsbedingungen. Die Benutzung Modelle zur Quantifizierung der Auswirkungen des Schwallbetriebs auf aquatische Ökosysteme befindet sich noch ganz am Anfang ihrer Entwicklung. Dabei ist die Herausforderung dieser Arbeit die Erstellung eines theoretischen Rahmens zur Untersuchung von abiotisch-biotischen Wechselwirkungen unter stark instationären Strömungsverhältnissen. Das vorgestellte Modell wird basierend auf thermodynamischen Gesetzen entwickelt. Dazu bildet die Energieerhaltung die Grundlage, insbesondere die Wechselwirkungen zwischen mechanischer, chemischer und thermischer Energie. Die Ziele dieser Dissertation sind: 1. Die Einbindung thermodynamischer Grundsätze/Gesetze in ein aquatisches Habitatmodell, welches auch bei stark instationären Strömungsverhältnissen effektiv eingesetzt werden kann. 2. Die Bewertung des Modells bezüglich theoretischer Grundlagen, Anwendbarkeit, und Leistung. In der vorliegenden Arbeit wird basierend auf thermodynamischen Grundsätzen ein neuartiges Fischhabitatmodell entwickelt. Dieses wird bei der Untersuchung alpiner Fließgewässer in Europa eingesetzt, die vom Schwallbetrieb betroffen sind. Des Weiteren wird gezeigt, dass ein erster Ansatz der nur auf die Energieerhaltung aufbaut, nicht ausreicht,um die Bioenergetik von Ökosystemen alpiner Fließgewässer ausreichend zu beschreiben. Daher ist es notwendig, in einem darauf aufbauenden Ansatz das Ökosystem zusätzlich bezüglich Entropie und Freier Enthalpie zu betrachten. Dieser zweite Ansatz (nach dem zweiten Hauptsatz) ermöglicht eine neue Darstellung von aquatischen Ökosystemen und stellt einen allgemein gültigeren Modellansatz dar, um die Auswirkungen auf Fische durch Schwall-Sunk-Betrieb unter realen Bedingungen abzuschätzen

Hydroacoustic and Pressure Turbulence Analysis for the Assessment of Fish Presence and Behavior Upstream of a Vertical Trash Rack at a Run-of-River Hydropower Plant

The spatial distribution of fish upstream of a vertical trash rack was investigated at the hydropower plant Kirchbichl in the alpine River Inn (Tyrol, Austria). The objective of the research project “FIDET” was to establish a non-invasive methodology to study fish presence and flow characteristics at large hydro power sites. A new monitoring approach was developed combining hydroacoustic observations of fish locations with multivariate hydrodynamic data. This was accomplished by utilizing complementary observations from multiple underwater sensor technologies: First, an array of echosounders were deployed at a fixed cross-section upstream of the trash rack for long-term monitoring. Afterwards, detailed underwater surveys with “acoustic cameras” (DIDSON and ARIS) revealed that the spatial distributions of fish in front of the trash rack were highly heterogeneous. The spatial distribution of the flow field was assessed via the time-averaged velocity fields from acoustic Doppler current profiler (ADCP). Finally, a custom pressure-based flow turbulence probe was developed, providing spatial estimates of flow turbulence immediately upstream of the trash rack. The significant contribution of this work is to provide a multi-modal monitoring approach incorporating both fish position data and hydrodynamic information. This forms the starting point for a future objective, namely to create an automated, sonar-based detection and control systems to assist and monitor fish protection operations in near real-time

Wearable technologies for monitoring aquatic exercises: A systematic review

Objective: To review methods for aquatic exercise monitoring using wearables. Data sources: Database search of PubMed, IEEEXplore, Scopus and Web of Science based on keywords, considering articles from the year 2000. The last search was performed on 26 October 2022. Review methods: Following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) protocol, eligible articles on water exercises were selected and summarized. Further screening process concentrated on studies exploiting wearable devices, organized according to demographics, purpose, protocols, outcomes and methods. A custom critical appraisal questionnaire was applied. Results: Out of the 1062 articles identified, 572 were considered eligible and subjected to preliminary synthesis. The final review focused on 27 articles featuring wearable devices applied to aquatic exercises. Four studies were disregarded as they applied wearable devices to determine daily physical activity or for sleep monitoring after training. Summary tables of 23 studies exploiting wearable devices for underwater motion analysis are provided, specifying the investigated parameters, major outcomes and study quality. This review identified four research gaps: (a) the absence of clinical protocols for underwater motion studies, (b) a deficit of whole-body studies, (c) the lack of longitudinal studies monitored via wearable devices and (d) the reliance of underwater studies on measurement and assessment methods developed for land-based investigations. Conclusions: This review emphasizes the need for both technological and methodological improvements for underwater motion analysis studies using wearables. We advocate for longitudinal clinical investigations with wearables to substantiate water exercise as an addition or replacement for land-based physical activity