scholarly journals Experimental Study on the Influence of an Artificial Reef on Cross-Shore Morphodynamic Processes of a Wave-Dominated Beach

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2947 ◽  
Author(s):  
Yue Ma ◽  
Cuiping Kuang ◽  
Xuejian Han ◽  
Haibo Niu ◽  
Yuhua Zheng ◽  
...  
Keyword(s):  
Morphological Evolution ◽  
Artificial Reef ◽  
Morphological Features ◽  
Coastal Protection ◽  
Swash Zone ◽  
State Transformation ◽  
Irregular Wave ◽  
Wave Flume ◽  
The Cross ◽  
Run Up

Artificial reefs are being implemented around the world for their multi-functions including coastal protection and environmental improvement. To better understand the hydrodynamic and morphodynamic roles of an artificial reef (AR) in beach protection, a series of experiments were conducted in a 50 m-long wave flume configured with a 1:10 sloping beach and a model AR (1.8 m long × 0.3 m high) with 0.2 m submergence depth. Five regular and five irregular wave conditions were generated on two types of beach profiles (with/without model AR) to study the cross-shore hydrodynamic and morphological evolution process. The influences of AR on the processes are concluded as follows: (1) AR significantly decreases the incident wave energy, and its dissipation effect differs for higher and lower harmonics under irregular wave climates; (2) AR changes the cross-shore patterns of hydrodynamic factors (significant wave height, wave skewness and asymmetry, and undertow), leading to the movement of shoaling and breaking zones; (3) the beach evolution is characterized by a sandbar and a scarp which respectively sit at a higher and lower location on the profile with AR than natural beach without AR; (4) the cross-shore morphological features indicate that AR can lead to beach state transformation toward reflective state; (5) the scarp retreat process can be described by a model where the scarp location depends linearly on the natural exponential of time with the fitting parameters determined by wave run-up reduced by AR. This study demonstrates cross-shore effects of AR as a beach protection structure that changes wave dynamics in surf and swash zone, reduces offshore sediment transport, and induces different morphological features.

scholarly journals WAVE RUN-UP OBSERVATIONS ON REVETMENTS WITH DIFFERENT POROSITIES

2012 ◽  
Vol 1 (33) ◽  
pp. 73 ◽  
Author(s):  
Stefan Schimmels ◽  
Michalis Vousdoukas ◽  
Dagmara Wziatek ◽  
Katharina Becker ◽  
Fabian Gier ◽  
...  
Keyword(s):  
Data Analysis ◽  
Concrete Block ◽  
Video Data ◽  
Coastal Protection ◽  
Large Wave ◽  
Wave Flume ◽  
New Type ◽  
Run Up ◽  
Highly Porous ◽  
Good Agreement

Wave run-up plays an important role in the design of coastal protection structures. However, none of the existing formulae for wave run-up predictions explicitly considers the effect of revetment porosity. Recently, two revetments have been tested in the Large Wave Flume (GWK) of Forschungszentrum Küste (FZK), a new type of highly porous polyurethane bonded (PBA revetment) revetment and a smooth interlocked pattern placed concrete block revetment (IPPB revetment), which is considered as “weakly permeable” for the present study. Wave run-up is evaluated by video data analysis based on timestack image processing. The results derived from the timestacks are compared to run-up data measured with conventional wire gauges and the good agreement demonstrates the accuracy and reliability of the video data analysis. The effect of the porosity of the revetment is incorporated into the EuroTop wave run-up formula, showing that for the present case it may reduce the relative run-up heights Ru,2%/Hm0 by about 25 % to 50 % as compared to a smooth impermeable slope.

scholarly journals Experimental Observation on Beach Evolution Process with Presence of Artificial Submerged Sand Bar and Reef

2020 ◽  
Vol 8 (12) ◽  
pp. 1019
Author(s):  
Cuiping Kuang ◽  
Yue Ma ◽  
Xuejian Han ◽  
Shunqi Pan ◽  
Lei Zhu
Keyword(s):  
Artificial Reef ◽  
Irregular Wave ◽  
Positive Effects ◽  
Sand Bars ◽  
Influence Mechanism ◽  
The Cross ◽  
Sand Bar ◽  
Set Up ◽  
Incident Waves ◽  
Morphodynamic Process

For observation on the influence mechanism of environmentally and aesthetically friendly artificial submerged sand bars and reefs in a process-based way, a set of experiments was conducted in a 50 m-long flume to reproduce the cross-shore beach morphodynamic process under four irregular wave conditions. The beach behavior is characterized by the scarp (indicating erosion) and the breaker bar (indicating deposition), respectively, and the scarp location can be formulated as a linear equation regarding the natural exponential of the duration time. Overall, main conclusions are: (1) the cross-shore structure of significant wave height and set-up is mainly determined by the artificial reef (AR); (2) the cross-shore distribution of wave skewness, asymmetry, and undertow (indicating shoaling and breaking) is more affected by the artificial submerged sand bar (ASB); (3) the ASB deforms and loses its sand as it attenuates incident waves, which leads to a complex sediment transport pattern; (4) the scarp retreat is related to the beach state, which can be changed by the AR and the ASB; (5) the AR, the ASB, and their combination decrease wave attack on the beach. In conclusion, this study proves positive effects of the AR and the ASB in beach protection through their process-based influences on beach behaviors and beach states for erosive waves.

scholarly journals Nonlinear Simulation of Wave Train Impact on a Vertical Seawall

Water ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 986 ◽  
Author(s):  
Dezhi Ning ◽  
Xiang Li ◽  
Chongwei Zhang
Keyword(s):  
Free Surface ◽  
Wave Train ◽  
Wave Load ◽  
Wave Impact ◽  
Nonlinear Simulation ◽  
Irregular Wave ◽  
Numerical Wave Flume ◽  
Wave Flume ◽  
Free Surface Oscillations ◽  
Run Up

A 2D nonlinear numerical wave flume is developed to investigate the wave train impact on a vertical seawall. Fully nonlinear kinematic and dynamic boundary conditions are satisfied on the instantaneous free surface. Cases of single-, double- and multi-crest wave trains are discussed. For single-crest wave train cases, the present nonlinear results are compared with the solution of the Serre-Green-Naghdi (SGN) model, showing good agreement. For double-crest wave train cases, the SGN model underestimates the maximum wave run-up along the vertical seawall. Compared with the linear results, the nonlinearity for double-crest cases can lead to an evident increase of the wave run-up and high-frequency free-surface oscillations. Through a fast Fourier analysis, evident nonlinear characteristics of the time series of the wave run-up and wave load during the wave impact process are confirmed. For multi-crest wave train cases, irregular wave run-ups can be observed. In some cases, the wave run-up along the vertical seawall can reach about 6 times that of the incident wave, which should be considered carefully in a practical design.

scholarly journals Field Observations of a Multilevel Beach Cusp System and Their Swash Zone Dynamics

Geosciences ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 148
Author(s):  
Siegmund Nuyts ◽  
Zili Li ◽  
Kieran Hickey ◽  
Jimmy Murphy
Keyword(s):  
Morphological Evolution ◽  
Swash Zone ◽  
Storm Events ◽  
Survey Period ◽  
Similarity Parameter ◽  
Global Theory ◽  
Astronomical Tide ◽  
Tidal Cycles ◽  
Aerial Vehicle ◽  
Beach Cusp

This paper presents the observed morphological evolution of a multilevel beach cusp system in Long Strand, Co. Cork, Ireland. The surveys were carried out with an Unmanned Aerial Vehicle (UAV) system between March and September 2019. From this site, three levels of beach cusps on the beachface (i.e., lower beach level, mid beach level and upper beach level), and critical cusp parameters are reported, including cusp spacing, cusp elevation, cusp depth, and cusp amplitude. Thus far, such an extensive dataset has not previously been reported in the literature from a single site. The evolution of the different cusp parameters is then linked with the hydrodynamics in the study area, and new prediction theories are proposed for the different cusp parameters. The Lower beach level cusps (1 < z < 2.5 m Irish Transverse Mercator (ITM)) changed with every tide and appeared when surf-similarity parameter -ξ0 < 1.55. These cusps had a mean cusp spacing of λmean = 11.09 m, which are closely linked with the predictions of the self-organisation theory (p < 0.05). In contrast, the Mid beach level cusps (2.5 < z < 3.5 m ITM) are less dynamic compared to the Lower beach level cusps and can persist between spring tidal cycles. They had a mean cusp spacing of λmean = 18.17 m. The Upper beach level cusps (approximately z = 6 m ITM) are above astronomical tide levels and have a mean cusp spacing of λmean = 40.26 m. They did not change significantly over the survey period due to a lack of major storm events. These findings give a better understanding of the evolution of different cusp parameters for a multilevel beach cusp system and can be used to formulate a global theory regarding their change over time.

scholarly journals ASSESSMENT OF COASTAL VULNERABILITY BASED ON THE USE OF INTEGRATED LOW-COST MONITORING APPROACH AND BEACH MODELLING: TWO ITALIAN STUDY

2020 ◽  
pp. 13
Author(s):  
Renata Archetti ◽  
Maria Gabriella Gaeta ◽  
Fabio Addona ◽  
Leonardo Damiani ◽  
Alessandra Saponieri ◽  
...  
Keyword(s):  
Low Cost ◽  
Integrated Approach ◽  
Video Monitoring ◽  
Monitoring Systems ◽  
Swash Zone ◽  
Coastal Vulnerability ◽  
Italian Study ◽  
Shoreline Evolution ◽  
Low Costs ◽  
Run Up

The use of video-monitoring techniques is significantly increased due to the diffusion of high-resolution cameras at relatively low-costs and they are largely used to estimate the shoreline evolution and wave run-up, as important coastal state indicators to be monitored and predicted for the assessment of flooding and erosion risks. In this work, we present an integrated approach based on the results from the low-cost video monitoring systems and the numerical modeling chain by means of SWAN and XBeach to accurately simulate and predict the swash zone processes.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/nLGNneJzmIU

scholarly journals Morphological evolution of through gorges in the stripe karst of the ridge Dzevrinska greda: North-eastern Serbia

2005 ◽  
Vol 85 (1) ◽  
pp. 3-10
Author(s):  
Jelena Calic ◽  
Marko Milosevic
Keyword(s):  
Morphological Evolution ◽  
Morphological Features ◽  
Drainage Network ◽  
Surface Drainage ◽  
North Eastern

The paper presents the main characteristics of the limestone ridge Dzevrinska Greda in north-eastern Serbia, which is a typical example of stripe karst (sub-type of contact karst). Dimensions and elongated shape of the limestone outcrop, as well as its position in relation to the surface drainage network, have led to formation of a number of short through gorges. The conditions of their formation and certain morphological features pointing to phases of their development are discussed in the paper. One of the indicators was the analysis of cave passages positions, which in most cases points to cave development in phreatic conditions. This means that the incision of through gorges is more recent than speleogenesis.

An artificial reef improves coastal protection and provides a base for coral recovery

2016 ◽  
Vol 75 (sp1) ◽  
pp. 467-471 ◽  
Author(s):  
Rodolfo Silva ◽  
Edgar Mendoza ◽  
Ismael Mariño-Tapia ◽  
María Luisa Martínez ◽  
Edgar Escalante
Keyword(s):  
Artificial Reef ◽  
Coastal Protection ◽  
Coral Recovery

Relativized Locality: Phases and Tiers in Long-Distance Allomorphy in Armenian

2021 ◽  
pp. 1-83
Author(s):  
Hossep Dolatian ◽  
Peter Guekguezian
Keyword(s):  
Morphological Features ◽  
Formal Property ◽  
Long Distance ◽  
Non Local ◽  
Morphological Processes ◽  
The Cross

Abstract Linguistic processes tend to respect locality constraints. In this paper, we analyze the distribution of conjugation classes in Armenian verbs. We analyze a type of Tense allomorphy which applies across these classes. On the surface, we show that this allomorphy is long-distance. Specifically, it is sensitive to the interaction of multiple morphemes that are neither linearly nor structurally adjacent. However, we argue that this allomorphy respects ‘relativized adjacency’ (Toosarvandani 2016) or tier-based locality (Aksënova, Graf, and Moradi 2016). While not surface-local, the interaction in Armenian verbs is local on a tier projected from morphological features. This formal property of tier-based locality is substantively manifested as phase-based locality in Armenian (cf. Marvin 2002). In addition to being well-studied computationally, tier-based locality allows us to capture superficially non-local morphological processes while respecting the cross-linguistic tendency of locality. We speculate that tier-based locality is a cross-linguistic tendency in long-distance allomorphy, while phase-based locality is not necessarily so.

scholarly journals RUN-UP OF PERIODIC WAVES ON BEACHES OF NON-UNIFORM SLOPE

1984 ◽  
Vol 1 (19) ◽  
pp. 23 ◽  
Author(s):  
Yoshinobu Ogawa ◽  
Nobuo Shuto
Keyword(s):  
Experimental Data ◽  
Wave Theory ◽  
Breaking Waves ◽  
Lagrangian Description ◽  
Periodic Waves ◽  
Swash Zone ◽  
Slope Method ◽  
Long Wave ◽  
Run Up ◽  
Better Than

Run-up of periodic waves on gentle or non-uniform slopes is discussed. Breaking condition and run-up height of non-breaking waves are derived "by the use of the linear long wave theory in the Lagrangian description. As to the breaking waves, the width of swash zone and the run-up height are-obtained for relatively gentle slopes (less than 1/30), on dividing the transformation of waves into dissipation and swash processes. The formula obtained here agrees with experimental data better than Hunt's formula does. The same procedure is applied to non-uniform slopes and is found to give better results than Saville's composite slope method.

scholarly journals WAVE RUN-UP AT SEA DIKES UNDER OBLIQUE WAVE APPROACH

1982 ◽  
Vol 1 (18) ◽  
pp. 50
Author(s):  
E. Tautenhain ◽  
S. Kohlhase ◽  
H.W. Partenscky
Keyword(s):  
Irregular Waves ◽  
Wave Direction ◽  
Wave Runup ◽  
Natural Conditions ◽  
Wave Impact ◽  
Oblique Wave ◽  
Wave Flume ◽  
Wave Approach ◽  
Impact Forces ◽  
Run Up

Besides wave impact forces, erosion of the inner side of a sea dike is a serious cause of destruction. Therefore, wave run-up and overtopping effects have to be considered with respect to the safety of a dike. Strong relations were found between both these influences (TAUTENHAIN et.al., 1980, 1981, 1982), based on experiments in a wave flume and using an energy conservation concept. However, under natural conditions, an oblique wave approach has to be considered. This paper deals with the influence of wave direction on wave runup on a smooth dike slope in order to provide a basis for calculating the overtopping rates for both regular and irregular waves.

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