Journal of Coastal and Hydraulic Structures 2022-04-13T16:24:58+00:00 JCHS Open Journal Systems <p>The Journal of Coastal and Hydraulic Structures (JCHS) is a completely free and open access community-based journal. All papers are rigorously peer-reviewed research in a double-blind fashion. Its mission is to publish high level engineering science results focused on the field of coastal and hydraulic structures.</p> Admissible post-wave overtopping flow for persons on a horizontal surface 2022-03-17T20:10:21+00:00 Jentsje Van der Meer Gosse Jan Steendam Tom Bruce Mark Klein Breteler <p>Admissible wave overtopping is a key parameter in design specifications and also in safety assessments of the crest level of many coastal structures. This paper considers the hazard to people/pedestrians by post-wave overtopping flow over a horizontal surface, like a dike or breakwater crest, or a boulevard. Such flow is given by a flow velocity and a flow thickness. The most recent guideline is given in EurOtop (2018), where a maximum overtopping wave volume of 600 l/m is seen as the admissible or tolerable maximum. But no flow velocities or flow thicknesses are given.</p> <p>Previous work has been summarised by Sandoval and Bruce (2017) who brought existing fluvial tests on people or human subjects together with data derived from videos of actual overtopping hazard events available from the internet. A graph was developed with stable and unstable combinations of flow velocity and flow depth or thickness.</p> <p>The paper describes first tests in the Delta Flume of Deltares with a volunteer exposed to wave overtopping hazard on the crest of a dike with wave heights up to 1.8 m. Analysis determines flow velocities and flow thicknesses for stable and unstable situations. Additional tests with the wave overtopping simulator on the crest of a dike are described. In these tests, flow velocities and flow thicknesses were accurately recorded as well as the reaction of a volunteer, guarded by a safety line, on the crest of the dike as well as on the landward slope. These tests gave also stable and unstable situations with known flow velocities and flow thicknesses.</p> <p>The new data were added to the work of Sandoval and Bruce (2017) and a physically based as well as a simple guideline has been proposed for the transition between stable and unstable situations for people/pedestrians. In general overtopping velocities are allowed of 4 m/s with a flow thickness of 0.2 m, but also a large velocity of 7 m/s with only a flow thickness of 0.1 m. Flow thicknesses are always given without air entrainment.</p> 2022-07-05T00:00:00+00:00 Copyright (c) 2022 Jentsje Van der Meer, Steendam, Prof. Bruce, Klein Breteler Assessment of maintenance efforts and probabilities of failure at German inland waterways to advance the design of bank revetments 2022-03-14T08:31:43+00:00 Julia Sorgatz Jan Kayser <p class="JCHSMaintext"><span lang="EN-US">Revetments protect waterways or flood defenses against erosion from waves and currents. In Germany a high percentage of about 7235 km of waterways is secured by revetments. Like many stakeholders of various infrastructures, the German Federal Waterways and Shipping Administration increasingly aims for a more economic and ecological design and maintenance strategy. Thus, new methodologies must be introduced that relate the structural condition of the revetment to resulting consequences such as required maintenance. In this paper we investigate the correlation of maintenance and revetment stability. Using the example of German inland waterways, maintenance measures conducted over at least six years are correlated with a deterministic and a probabilistic stability assessment. To account for realistic traffic loads, the stability assessment employs field measurements which provide data on ship-induced waves. It was found that at least a linear correlation between revetment stability and maintenance must be assumed. A comparison between the deterministic and the probabilistic stability assessment and thereby obtained correlations shows that less maintenance is predicted with the deterministic stability assessment. Particularly for small sample sizes and small probabilities of failure, the probabilistic approach should be favored over the deterministic approach to account for various uncertainties. In the case that only maintenance is of relevance for design considerations, the results of the probabilistic approach indicate that β = 1.3 (p<sub>f</sub> ≈ 10<sup>-1</sup>) may be a suitable annual target reliability.</span></p> 2022-06-23T00:00:00+00:00 Copyright (c) 2022 Julia Sorgatz, Jan Kayser Loads and effects of ship-generated, drawdown waves in confined waterways - A review of current knowledge and methods 2022-02-01T20:21:25+00:00 León-Carlos Dempwolff Gregor Melling Christian Windt Oliver Lojek Tobias Martin Ingrid Holzwarth Hans Bihs Nils Goseberg <p>A ship in motion generates a complex wave field consisting of several superimposed wave systems. The relevance of the wave systems' components varies, depending on individual ship and waterway parameters. This review work is specifically concerned with the long-period, primary wave system, large-volume ships travelling through confined waterways, generate, as it may exert intensive wave and current loading on the banks, affecting local morphology, engineering structures and ecology</p> <p>So far, the effect of ship-generated waves on waterway embankments has yet only routinely been considered for inland waterways with a constant cross-section. Less attention has been payed to the ship-induced wave and current loading in more complex bathymetries like coastal waterways and estuaries, as naturally occurring loads had been thought to dominate. However, the hydrodynamic loads induced by ships grow and become increasingly relevant in coastal waterways, due to continuously growing dimensions of sea-going ships.</p> <p>At the same time, requirements rise to allow for restoring the ecological value of of inland and coastal waterways, leading to spatially more diverse bathymetries and embankment structures. Hence, the prediction of ship-generated primary wave magnitudes at banks becomes increasingly complex, due to deformation processes of the propagating waves in shallow water. Knowledge on ship-generated waves characteristics and methods to predict induced loads are thus essential for the assessment of bank stability and the dimensioning of engineering structures to resist present-day and prospective ship-induced loads.</p> <p>This review paper compiles, analyzes and assesses the findings of previous research quantifying the relevance of primary waves for the surrounding waterways and shows interconnections to the questions studied within naval hydrodynamics for confined waterways. Commonly applied methods for wave prediction are reviewed, highlighting their relevance and limitations. Finally, a concept for coupled numerical model development is suggested, based on the success of different modelling approaches presented previously.</p> 2022-05-10T00:00:00+00:00 Copyright (c) 2022 León-Carlos Dempwolff, Gregor Melling, Christian Windt, Oliver Lojek, Tobias Martin, Ingrid Holzwarth, Hans Bihs, Nils Goseberg Magnification of Tsunami Risks Due to Sea Level Rise Along the Eastern Coastline of Japan 2022-01-19T14:45:26+00:00 Kentaro Koyano Tomoyuki Takabatake Miguel Esteban Tomoya Shibayama <p class="JCHSAbstractText"><span lang="EN-US">Sea level rise is likely to increase the risks of inundation due to coastal hazards in the course of the 21st century. To understand how different sea level rise (SLR) scenarios will affect the disaster risk management of tsunamis in Japan, the authors applied the Probabilistic Tsunami Hazard Assessment (PTHA), using a logic tree approach, to the eastern coastline of Japan. Considering a similar generation zone as the 2011 Tohoku Earthquake and Tsunami, a number of tsunami propagation simulations were conducted. In the logic tree construction, different branches of magnitude ranges, positions of asperity, recurrence intervals, standard deviations of log-normal distribution and truncations of log-normal distribution were set. The results indicate that the maximum water levels at output points increased according to the different SLR scenarios that were considered. It was also found that the effects that SLR has on expected tsunami heights and 90% confidence intervals are nonlinear and could vary according to location. Such results highlighted the importance of considering the effects of SLR to improve emergency response capacity.</span></p> 2022-04-14T00:00:00+00:00 Copyright (c) 2022 Kentaro Koyano Analytical Models for Determining the Propagation of Rectangular Surface Jets for Fishway Attraction Flow 2022-04-13T16:24:58+00:00 Veronika Wiering Patrick Heneka Martin Henning Linda Bergmann <p>The present paper evaluates suitability of two analytical models to determine the propagation of rectangular surface jets as a tool to design fishway attraction flow. It focuses on rectangular orifices of vertical slot fishways with aspect ratios (width-to-height) for W/H &lt; 1. Both models were rewritten to match boundary conditions for fishways because they were initially derived for horizontal orifices. As the basis for the evaluation, the output of the analytical models to RANS simulations for 12 geometries 1/16 &lt;= W/H &lt;= 4 is compared. Applied analytical equations for half-lengths for cases W/H &gt;= 4 are within 5 % of RANS modeling results for all cases. The location of centerline transition locations from analytical models also agree reasonably well with RANS modeling. The findings support efficient design of optimum attraction flow propagation using simple, rapid analytical approaches.</p> 2022-04-13T00:00:00+00:00 Copyright (c) 2022 Veronika Wiering, Patrick Heneka, Martin Henning, Linda Bergmann