David F. Vetsch


Last Name

Vetsch

First Name

David F.

ORCID

0000-0003-3293-5831

Organisational unit

03820 - Boes, Robert / Boes, Robert

Search Results

Publications 1 - 10 of 109
  • Analysis And Optimization of Hydraulic Characteristics at Fish Guidance Structures Using CFD
    Item type: Conference Paper
    Leuch, Claudia; Beck, Claudia; Albayrak, Ismail; et al. (2022)
    Proceedings 39th IAHR World Congress
    Mechanical behavioural fish guidance racks (FGR) with vertical bars are a promising technical solution for the safe downstream movement of fish at run-of-river hydropower plants (HPP) and water intakes. They do not pose a physical barrier to most fish but rather create flow patterns that deter fish from passing the bar rack and guide them towards a bypass system. Current knowledge of flow parameters that induce this avoidance behaviour is limited. Furthermore, FGR may impair the energy production and operation of HPP as they generate additional head losses and affect the turbine admission flow through deflection of the current. In order to provide a widely applicable and robust solution, a balance between effective fish guidance and minimal hydraulic losses needs to be found. In this study, a computational fluid dynamics (CFD) approach is used to efficiently test and compare different bar shapes and their impact on the flow field both upstream and downstream of the FGR. The results show that the use of hydro-dynamically shaped bars significantly improves the hydraulic performance of the rack. Furthermore, the study proves that CFD modelling is a valuable tool for this kind of analysis as parameters can easily be adapted and the results can be obtained in high spatial and temporal resolution.
  • Integrated hazard assessment of lake tsunamis triggered by subaqueous and subaerial landslides
    Item type: Conference Paper
    Strupler, Michael; Bürgler, Matthias; Vetsch, David F.; et al. (2023)
    Proceedings of the 9th International SUT Offshore Site Investigation and Geotechnics: Innovative Geotechnologies for Energy Transition
    Historical chronicles together with geophysical, geotechnical, and sedimentological investigations have demonstrated that both subaqueous and subaerial landslides can lead to tsunamis on lakes. Previous work has shown that lakes in the alpine and peri-alpine settings in Switzerland provide prime preconditions for subaqueous mass movements, due to the glacially excavated basin geometry, the continuous sediment supply, and the related mechanical characteristics of the slopes. In addition, steep alongshore topography favours subaerial mass movements. The increasing settlement and infrastructure development along the shores and the lake tsunami history emphasize that assessing the tsunami hazard on Swiss peri-alpine lakes is essential. In a holistic approach that combines limnogeological, geomorphological, seismological, geotechnical, geospatial techniques with hydrodynamic simulations, we construct a workflow for the assessment of the landslide-tsunami hazard on peri-alpine lakes. GPU-accelerated numerical simulation using the freely available software BASEMENT allows for a rapid calculation of various inundation parameter distributions, considering uncertainties in landslide parameters. In the workflow, tsunami generation can be simulated both for subaqueous and subaerial mass movements. Hence, the hazard of lake tsunamis can be assessed comprehensively. Next to presenting the workflow, we provide recommendations for future work.
  • Tsunamis ausgelöst durch Unterwasserrutschungen in Seen
    Item type: Conference Paper
    Fuchs, Helge; Evers, Frederic M.; Razmi, Amir; et al. (2018)
    Wasserbausymposium Graz 2018: Wasserwirtschaft - Innovation aus Tradition. Tagungsband
  • BASEveg: A python package to model riparian vegetation dynamics coupled with river morphodynamics
    Item type: Journal Article
    Caponi, Francesco; Vetsch, David F.; Vanzo, Davide (2023)
    SoftwareX
    River morphology is closely linked with riparian vegetation dynamics, because of the interwoven interactions between plants, flow, and sediment transport. However, open-source tools that model such interactions are currently missing. Here we present BASEveg, a python package to simulate riparian vegetation dynamics coupled with BASEMENT, a river hydro-morphodynamic simulator. BASEveg calculates plant growth based on water table fluctuations during low flow and incorporates the resulting plant properties affecting water flow and sediment transport on the computation of riverbed changes during floods. This new tool empowers scientists from different disciplines and fluvial managers to explore eco-morphodynamic processes at various spatial and temporal scales.
  • Systematic comparison of 1D and 2D hydrodynamic models for the assessment of hydropeaking alterations
    Item type: Journal Article
    Bürgler, Matthias; Vetsch, David F.; Boes, Robert; et al. (2023)
    River Research and Applications
    Numerical hydrodynamic models enable the simulation of hydraulic conditions under various scenarios and are thus suitable tools for hydropeaking related assessments. However, the choice of the necessary model complexity and the consequences of modelling choices are not trivial and only few guidelines exist. In this study, we systematically evaluate numerical one-dimensional (1D) and two-dimensional (2D) hydrodynamic models with varying spatial resolution regarding their suitability as input for hydropeaking-sensitive, ecologically relevant hydraulic parameters (ERHPs), and their computational efficiency. The considered ERHPs include the vertical dewatering velocity, the wetted area variation between base and peak flow and the bed shear stress as a proxy for macroinvertebrate drift. Furthermore, we quantified the habitat suitability of brown trout for different life stages. The evaluation is conducted for three channel planforms with morphological characteristics representative for regulated Alpine Rivers, ranging from alternating bars to a braiding river morphology. For the prediction of habitat suitability and bed shear stress, a 1D model appears to be always insufficient, and a highly resolved 2D model is suggested. Reducing the spatial resolution of 2D models leads to computational efficiency similar to 1D, while providing more accurate results. Thus, our results suggest, that while a highly resolved 1D model is sufficient for accurate predictions of the dewatering velocity and wetted area in the less complex alternating bar morphology, a 2D model is recommended for more complex wandering or braiding morphologies. This study can serve as guideline for researchers and practitioners in the selection and setup of hydrodynamic models for hydropeaking.
  • Sedimentation in a narrow reservoir under climate change and sediment bypass tunnel operation scenarios
    Item type: Conference Paper
    Dahal, Sudesh; Evers, Frederic M.; Boes, Robert; et al. (2024)
    Proceedings of the 10th International Symposium on Hydraulic Structures (ISHS 2024)
    Reservoir sedimentation is one of the main issues interfering with the sustainable operation of many hydropower reservoirs as it causes a reduction of storage capacity and may also affect dam safety. The rate of sedimentation is anticipated to change due to changes in flow following climate change. Although quantifying the variation of sedimentation is subject to high uncertainty, sediment yield is mainly expected to increase for Alpine catchments due to retreating glaciers and thawing permafrost. Sediment Bypass Tunnels (SBTs) are hydraulic structures to counteract sedimentation problems as they allow for bypassing incoming sediment (bedload and parts of the suspended load) around the dam into the tailwater reach. This study deals with the SBT in Solis reservoir (Switzerland) where an SBT has been operating for more than a decade to counteract sedimentation. The aim is to evaluate the performance of the Solis SBT under climate scenarios by conducting 1D numerical simulations. The HydroCH2018-Runoff ensemble is referred for the future projection of river inflows into the Solis reservoir. In absence of quantified impact on the sediment input, it is computed from calibrated sediment transport equations based on monitored data. The model is found useful to simulate future sedimentation and to compare scenarios of SBT operation during flood events. Considering the impact of SBT operation on energy generation due to water losses, SBT operation during two different floods is more effective than its operation in a single flood for a given total duration of operation.
  • Composite Modeling to Detect Scale Effects in Embankment Dam Breaching due to Overtopping
    Item type: Conference Paper
    Halso, Matthew Christopher; Knüsel, C.L.; Vetsch, David F.; et al. (2024)
    Proceedings of the 10th International Symposium on Hydraulic Structures (ISHS 2024)
    The failure of a dam can have catastrophic consequences for populations and infrastructure downstream. The processes of dam failure are typically studied with small to medium scale laboratory physical model investigations. Findings from laboratory scale studies should inform decision making for prototype scale dams, but upscaling introduces uncertainties and complexity. Detailed numerical models can simulate complex breach processes and depict larger dams, allowing for investigations at larger scale. But with increasing detail and numerical refinement comes increasing computational cost, making modeling of prototype systems potentially prohibitive. Parametric numerical models allow for efficient simulation at prototype scale, but with simplified geometries and limited erosion processes. These numerical options could connect findings from smaller scale studies to prototype scale, if the effect of scale in each method is accounted for. In this study, the effect of scale is investigated with medium laboratory scale (dam height = 0.5 m) and large laboratory scale (dam height = 1.0 m) breach modeling. Laboratory experiments, detailed numerical modeling, and parametric numerical modeling (with the Macchione and Peter methods) are performed at both scales. During initial breach formation (while reservoir head was constant), the laboratory experiments showed no effect of scale. Later, as the reservoir head fell, a faster increase in breach discharge occurred at large scale, leading to an earlier peak discharge. Detailed numerical modeling showed the effect of scale on breach growth, but with limited reproduction of the effect on breach discharge. Both parametric methods replicated the discharge hydrographs well, but only the Peter model adequately reproduced the effect of scale on timing of peak discharge.
  • Flow around an isolated boulder-like obstacle: effects of modeling approach and Reynolds number
    Item type: Conference Paper
    Marschall, Yannick; Constantinescu, George; Boes, Robert; et al. (2024)
    Proceedings of the 10th International Symposium on Hydraulic Structures (ISHS 2024)
    We conducted unsteady Reynolds-Averaged Navier Stokes (URANS) and detached eddy simulations (DES) to simulate the flow around a boulder-like obstacle placed at the bottom of an open channel at laboratory scale (obstacle width B=7 cm) and at a larger scale (B=21 cm), while keeping the channel Froude number constant. The obstacle shape was generated from a three- dimensional scan of a stone. The study discusses the effects of the turbulence modelling approach (URANS vs. DES) and scale effects. An increase of the drag coefficient of around 10-15% was observed for the simulations conducted at larger scale. Part of this difference can be attributed to differences in the fully developed velocity profiles in the approach flow which are a function of the Reynolds number. Maintaining the boulder size, the drag coefficient predicted by URANS is about 15% smaller than the DES value. URANS overestimates the wake recirculation region leading to a slightly higher pressure acting on the downstream side of the boulder. The results of this investigation show that URANS methods, which are widely used for practical applications in hydraulic engineering, can predict reasonably well the mean flow field and the quantities of engineering interest. Computationally more expensive methods like DES, that resolve a large part of the energetically important eddies in the flow, provide more accurate predictions of the mean quantities and allow investigating the flow physics based on the simulated dynamics of the large-scale coherent structures.
  • Impact of bed level changes on overflow at lateral diversion structures using different numerical modelling approaches
    Item type: Conference Paper
    Frei, Seline; Boes, Robert; Vetsch, David F. (2024)
    Proceedings of the 10th International Symposium on Hydraulic Structures (ISHS 2024)
    Lateral diversion structures in rivers, such as side weirs or overflow embankments, are common measures to divert a part of the discharge into a lateral retention area or into a flood corridor during larger flood events. The lateral overflow reduces discharge and thus bedload transport capacity in the main channel, leading to local deposition near the lateral diversion structure and sediment aggradation downstream of the structure. The bed level rise may lead to considerably increased lateral overflow compared to the situation without bedload deposition. This should be considered in the design of lateral diversion structures. Systematic morphodynamic 1D, 1D-2D coupled and 2D simulations with the BASEMENT software were carried out to analyse the interaction between lateral overflow and changes in bed level. All modelling approaches are able to reproduce the sediment aggradation downstream of the lateral diversion structure and show increased lateral overflow compared to a simulation without bed level changes. The choice of modelling approach to simulate the lateral overflow depends on the model requirement, data availability and objectives.
  • Notentlastung des Linthkanals im Überlastfall
    Item type: Conference Paper
    Seitz, Peter; Berchtold, Thomas; Weitbrecht, Volker; et al. (2012)
    Wasserbausymposium 2012: Wasser - Energie, global denken - lokal handeln. Tagungsband
Publications 1 - 10 of 109