scholarly journals LARGE SCALE TESTS ON FORESHORE EVOLUTION DURING STORM SEQUENCES AND THE PERFORMANCE OF A NEARLY VERTICAL STRUCTURE

2018 ◽  
pp. 13 ◽  
Author(s):  
Riccardo Briganti ◽  
Rosaria Ester Musumeci ◽  
Jentsje Van der Meer ◽  
Alessandro Romano ◽  
Laura Maria Stancanelli ◽  
...  
Keyword(s):  
Large Scale ◽  
Water Levels ◽  
Beach Sand ◽  
Swash Zone ◽  
The European Union ◽  
Large Wave ◽  
Wave Flume ◽  
Wave Conditions ◽  
Almost All ◽  
Large Scale Tests

This work presents the results of an experimental investigation on the effects of a sequence of storms on wave overtopping at a nearly vertical battered seawall at the back of a sandy foreshore. The experiments were carried out in the Large Wave Flume (GWK) at Leibniz Universität Hannover (Germany), as part of the research project ICODEP (Impact of Changing fOreshore on flood DEfence Performance), within the European Union programme Hydralab+. The layout consisted of a 10/1 battered seawall and a natural sandy foreshore with an initial 1:15 slope. The beach sand had a nominal diameter of 0.30 mm. Three storm sequences were simulated, where each consisted of three individual storms. Each storm was divided into six steps in which the wave conditions and still water level were varied to represent the peak of an actual storm. The six sea states were based on a JONSWAP spectral shape, with wave heights roughly between 0.6 m and 0.8 m. Two still water levels were tested. For the central two steps the level was such that the freeboard was only 0.14 m and almost all waves were overtopping. In the remaining steps low still water levels were employed, leaving a narrow swash zone. Two storm profiles were considered, the first one with a lower level of energy and the second one with a higher one. These were combined in the three different sequences. All the tested wave conditions were designed to be erosive for the beach, with no recovery in between. Each sequence started from a plain beach configuration and the beach was not restored in between storms. The measurements included waves, pressure and forces, sediment concentrations and flow velocity together with overtopping. The profile of the beach was measured after each sea state tested.

Observations of wave attenuation, scour, and subsurface pore pressures acrossbthree marsh restoration sill structures on a sandy bed

Shore & Beach ◽  
2020 ◽  
pp. 14-30
Author(s):  
Jordan Converse ◽  
Meagan Wengrove ◽  
Pedro Lomonaco
Keyword(s):  
Sediment Transport ◽  
Large Scale ◽  
Wave Attenuation ◽  
Oyster Shell ◽  
Water Levels ◽  
Structure Stability ◽  
Large Wave ◽  
Sea Levels ◽  
Wave Flume ◽  
Living Shoreline

With rising sea levels and more frequent exposure to extreme storms, coastlines worldwide are vulnerable to increased erosion and loss of natural marsh lands. In an effort to lessen these impacts, there is a growing practice of adapting hard or “gray” coastline protection techniques to more nature-based features that promote habitat and ecosystem health. Living shoreline marsh restorations utilize natural and naturebased materials to protect marsh shores from erosion while also allowing intertidal flushing to promote the health and diversity of the marsh. Our study investigates three types of living shoreline sill designs exposed to average and storm-energy wave conditions at varying water levels. The sills were designed to mimic constructed sills in practice (rock, oyster shell, tree root wads), but more generally vary in structure porosity and material dissipation potential. Large-scale laboratory experiments were conducted in the large wave flume at the O.H. Hinsdale Wave Research Laboratory. Wave transmission and reflection are used to demonstrate wave attenuation capability of each sill structure. Scour of the sill, bedload sediment transport rates on the seaward and shoreward sides of the sill, and sediment pore-water vertical hydraulic gradients were used to demonstrate the potential for sediment transport and liquefaction. Results will contribute to understanding the effect of sill material porosity and mass on structure stability, and the effectiveness of using green living shoreline sill structures in the continued effort to establish design criteria for living shoreline implementation.

scholarly journals High-resolution, large-scale laboratory measurements of a sandy beach and dynamic cobble berm revetment

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Chris E. Blenkinsopp ◽  
Paul M. Bayle ◽  
Daniel C. Conley ◽  
Gerd Masselink ◽  
Emily Gulson ◽  
...  
Keyword(s):  
Large Scale ◽  
Sandy Beach ◽  
Wave Transformation ◽  
Intermediate Water ◽  
Swash Zone ◽  
Laboratory Measurements ◽  
Large Wave ◽  
Water Level Rise ◽  
Wave Flume ◽  
Spatio Temporal

AbstractHigh quality laboratory measurements of nearshore waves and morphology change at, or near prototype-scale are essential to support new understanding of coastal processes and enable the development and validation of predictive models. The DynaRev experiment was completed at the GWK large wave flume over 8 weeks during 2017 to investigate the response of a sandy beach to water level rise and varying wave conditions with and without a dynamic cobble berm revetment, as well as the resilience of the revetment itself. A large array of instrumentation was used throughout the experiment to capture: (1) wave transformation from intermediate water depths to the runup limit at high spatio-temporal resolution, (2) beach profile change including wave-by-wave changes in the swash zone, (3) detailed hydro and morphodynamic measurements around a developing and a translating sandbar.

scholarly journals Large-Scale Laboratory Experiments on Mussel Dropper Lines in Ocean Surface Waves

2020 ◽  
Vol 9 (1) ◽  
pp. 29
Author(s):  
Rebekka Gieschen ◽  
Christian Schwartpaul ◽  
Jannis Landmann ◽  
Lukas Fröhling ◽  
Arndt Hildebrandt ◽  
...  
Keyword(s):  
Large Scale ◽  
Laboratory Experiments ◽  
Blue Mussel ◽  
Farming Systems ◽  
Quality Parameter ◽  
Large Wave ◽  
Marine Aquaculture ◽  
Ocean Surface Waves ◽  
Wave Flume ◽  
Waves And Currents

The rapid growth of marine aquaculture around the world accentuates issues of sustainability and environmental impacts of large-scale farming systems. One potential mitigation strategy is to relocate to more energetic offshore locations. However, research regarding the forces which waves and currents impose on aquaculture structures in such conditions is still scarce. The present study aimed at extending the knowledge related to live blue mussels (Mytilus edulis), cultivated on dropper lines, by unique, large-scale laboratory experiments in the Large Wave Flume of the Coastal Research Center in Hannover, Germany. Nine-months-old live dropper lines and a surrogate of 2.0 m length each are exposed to regular waves with wave heights between 0.2 and 1.0 m and periods between 1.5 and 8.0 s. Force time histories are recorded to investigate the inertia and drag characteristics of live mussel and surrogate dropper lines. The surrogate dropper line was developed from 3D scans of blue mussel dropper lines, using the surface descriptor Abbott–Firestone Curve as quality parameter. Pull-off tests of individual mussels are conducted that reveal maximum attachment strength ranges of 0.48 to 10.55 N for mussels that had medium 3.04 cm length, 1.60 cm height and 1.25 cm width. Mean drag coefficients of CD = 3.9 were found for live blue mussel lines and CD = 3.4 for the surrogate model, for conditions of Keulegan–Carpenter number (KC) 10 to 380, using regular wave tests.

Environmentally driven escalation of host egg rejection decimates success of an avian brood parasite

2020 ◽  
Vol 31 (6) ◽  
pp. 1316-1325 ◽  
Author(s):  
John M Eadie ◽  
Bruce E Lyon
Keyword(s):  
Large Scale ◽  
Ecological Factors ◽  
Water Levels ◽  
Environmental Drivers ◽  
Egg Rejection ◽  
Vital Rates ◽  
Brood Parasite ◽  
Parasitic Lifestyle ◽  
Almost All ◽  
Rejection Rates

Abstract The black-headed duck (Heteronetta atricapilla) of South America is the only known avian obligate brood parasite with precocial offspring. In Argentina, it relies on two species of coots as primary hosts, which typically reject 35–65% of duck eggs. We show that environmentally driven increases in host egg rejection behavior lead to substantial reductions in the reproductive success of the brood parasite. Episodes of flooding and vegetation loss caused dramatic shifts in host egg-rejection behavior, resulting in rejection (85–95%) of almost all duck eggs. Coots respond to fluctuating water levels by building up their nest, raising their own eggs but leaving duck eggs behind. Coots can apparently recognize parasitic duck eggs, but large-scale rejection is triggered only when hosts must actively make a choice. We use a simple population model to illustrate the unique demographic challenges that black-headed ducks face with their parasitic lifestyle and to explore the potential impact of environmentally induced escalation of egg rejection. Using the best available estimates for key vital rates, we show that obligate parasitism may provide a demographically precarious existence for black-headed ducks, even under benign environmental conditions. Environmentally mediated increases in egg rejection rates by hosts could impact significantly the viability of this enigmatic species of brood parasitic duck. Our results demonstrate that egg rejection rates are not fixed properties of host populations or individuals but are strongly influenced by social and ecological factors. Shifts in these environmental drivers could have important and unforeseen demographic consequences for brood parasites.

scholarly journals BREAKING AND WASH UP OF SOLITARY WAVES ON A COMPOSITE BEACH

2020 ◽  
pp. 29
Author(s):  
Hajo von Hafen ◽  
Jacob Stolle ◽  
Nils Goseberg ◽  
Ioan Nistor
Keyword(s):  
Solitary Waves ◽  
Horizontal Plane ◽  
Large Scale ◽  
Propagation Path ◽  
Rock Falls ◽  
Damage Potential ◽  
Large Wave ◽  
Beach Slope ◽  
Wave Flume ◽  
Run Up

Hazardous events, such as landslides, rock slides, rock falls or avalanches often generate extreme, impulsive waves when entering water bodies (Fuchs & Hager, 2015). These waves are approximated by solitary waves and researchers investigate their damage potential when inundating built environment. Deepening the understanding of solitary waves running up a uniform beach slope and propagating over a subsequent horizontal plane can help to reduce and mitigate damage and the number of casualties caused by such a hazardous event. So far, few authors addressed this specific setting near-shore (Fuchs & Hager, 2015; Zelt & Raichlen, 1991). In this study, large scale solitary waves propagate about 200 m in in the Large-Wave Flume (GWK, 307 m 5 m 7 m) at the Coastal Research Center in Hannover, Germany then they run up a beach slope and subsequently break, generating a bore which advances onto a subsequent, initially dry, horizontal surface. Unlike previous studies, the generated solitary waves broke close to the edge between the beach slope and the horizontal plane section. The overall aim of this study is to investigate the characteristics of the broken waves' dynamics. In addition, their surge profile and front celerity are compared to those of the non-breaking solitary waves. Subsequently, the differences between the velocity regimes along the bore propagation path are presented and linked to the fundamental physical processes behind.

scholarly journals LOADING OF VERTICAL WALLS BY OVERTOPPING BORES USING PRESSURE AND FORCE SENSORS - A LARGE SCALE MODEL STUDY

2012 ◽  
Vol 1 (33) ◽  
pp. 44 ◽  
Author(s):  
Karunya Ramachandran ◽  
Rebeca Roldan Genzalez ◽  
Hocine Oumeraci ◽  
Stefan Schimmels ◽  
Matthias Kudella ◽  
...  
Keyword(s):  
Large Scale ◽  
Vertical Wall ◽  
Pressure Sensors ◽  
Scale Model ◽  
Force Sensors ◽  
Research Project ◽  
Joint Research ◽  
Large Wave ◽  
Wave Flume ◽  
Joint Research Project

This study is based on the data obtained from tests carried out in the Large Wave Flume (Grosser Wellenkanal (GWK)) in Hannover in the frame of a joint research project of Ghent University (Belgium) and Forschungszentrum Küste (FZK, Germany). The goal of the research project is to determine the wave induced loads on vertical storm walls located at the end of overtopped dike, which are designed to protect coastal cities from overtopping and floods. The loads resulting from waves overtopping the dike and impacting the vertical wall as a bore are measured by means of both force and pressure sensors. This paper describes the results of pressure and force records at the vertical wall, including a comparative analysis of the overall forces obtained by pressure integration and force sensors for two different wall setups: Fully blocked wall and partially blocked wall.

Small and Large Scale Experimental Investigations of Wave Loads on a Slender Pile Within Closely Spaced Neighbouring Piles

2014 ◽  
Author(s):  
Lisham Bonakdar ◽  
Hocine Oumeraci
Keyword(s):  
Laboratory Tests ◽  
Large Scale ◽  
Model Tests ◽  
Scale Model ◽  
Research Centre ◽  
Experimental Investigations ◽  
Small Scale ◽  
Wave Loads ◽  
Large Wave ◽  
Wave Flume

Wave loads on a slender pile within a group of piles are studied by means of (i) large-scale laboratory tests carried out in the Large Wave Flume (GWK) of the Coastal Research Centre (FZK) in Hannover, and (ii) small scale experiments performed in 2 m-wide wave flume of Leichtweiss-Institute for Hydraulic Engineering and Water Resources (LWI), in Braunschweig, Germany. The small scale model tests (LWI) were scaled down (1:6.5) by Froude law from the large scale model tests (GWK). Scale and model effects are examined by comparing the results of small and large scale laboratory tests.

scholarly journals NUMERICAL STUDY OF WAVE RUN-UP AT PERMEABLE FIXED REVETMENT SLOPE

2017 ◽  
pp. 32
Author(s):  
Izmail Kantarzhi ◽  
Sergii Kivva ◽  
Natalia V Shunko
Keyword(s):  
Porous Medium ◽  
Numerical Model ◽  
Large Scale ◽  
Numerical Study ◽  
Water Filtration ◽  
Wave Surface ◽  
Natural Conditions ◽  
Wave Flume ◽  
Run Up ◽  
Large Scale Tests

The numerical model of wave surface elevation and water filtration in the saturated-unsaturated porous medium is developed. The model uses to define the parameters of the wave run-up at the slope protected by the permeable fixed layer. The model shows the wave surface in the different times, including the wave run-up height at the slope and wave run-down. Also, the velocities in the upper protected layer as well in the soil body of the slope are defined. Model is verified with using of the published large-scale tests with the slopes protected by Elastocoast technology layers. The tests were carried out in the wave flume of Technical University Braunschweig. The numerical model may be applied to calculate the maximal waves run-up at the protected engineering and beach slopes in natural conditions.

scholarly journals CROSS-SHORE SEDIMENT TRANSPORT IN THE SWASH ZONE: LARGE-SCALE LABORATORY EXPERIMENTS

2020 ◽  
pp. 18
Author(s):  
Sara Dionisio Antonio ◽  
Jebbe van der Werf ◽  
Bart Vermeulen ◽  
Ivan Caceres ◽  
Jose M. Alsina ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Large Scale ◽  
Surf Zone ◽  
Transport Processes ◽  
Sand Transport ◽  
Swash Zone ◽  
Flume Experiments ◽  
Wave Flume ◽  
Shoreline Evolution

The swash zone is a highly dynamic boundary between the beach and the surf zone. Swash processes determine whether sediment is either stored on the upper beach or is transported offshore, and thus strongly affect shoreline evolution. The present research focuses on the hydrodynamics, sand transport processes and net sediment transport in the swash zone through a series of large-scale wave flume experiments. This research aims to improve the understanding of swash zone sand transport processes, in particular the role of cross-shore sand advection and wave-swash interactions, and bring new detailed insights into the relation between intra-swash processes and net sand transport rates.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/tYvJ0pML-kU

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