scholarly journals DYNAMIC NOURISHMENT AND MULTI-PURPOSE ARTIFICIAL REEF AS A BEACH EROSION COUNTERMEASURE

2018 ◽  
pp. 27
Author(s):  
Kyu-Tae Shim ◽  
Kyu-Han Kim ◽  
Nobuhisha Kobayashi
Keyword(s):  
Sediment Transport ◽  
Power Plant ◽  
Large Scale ◽  
Artificial Reef ◽  
Beach Erosion ◽  
Induced Current ◽  
Erosion And Deposition ◽  
Severe Erosion ◽  
Transport Patterns ◽  
Wave Induced

Presently, various energy power plant facilities are being constructed along the coast of the East Sea of Korea. Large-scale breakwaters are also being constructed seaward of these facilities in order to create a tranquil area for the docking facilities of ships as well as to minimize the damaging effects of tsunamis and storm surge. The construction of such large-scale coastal infrastructures has changed the wave-induced current and sediment transport patterns and caused severe erosion and deposition on the beach.

scholarly journals RELATION BETWEEN WAVE-INDUCED CURRENT AND ALGAE COMMUNITY ON ARTIFICIAL REEF

2002 ◽  
Vol 46 ◽  
pp. 977-982 ◽  
Author(s):  
Kimhito INOUE ◽  
Hitoshi TANAKA ◽  
Osamu NISHIMURA ◽  
Satoshi BABA
Keyword(s):  
Artificial Reef ◽  
Induced Current ◽  
Wave Induced

scholarly journals From Ripples to Large-Scale Sand Transport: The Effects of Bedform-Related Roughness on Hydrodynamics and Sediment Transport Patterns in Delft3D

2020 ◽  
Vol 8 (11) ◽  
pp. 892
Author(s):  
Laura Brakenhoff ◽  
Reinier Schrijvershof ◽  
Jebbe van der Werf ◽  
Bart Grasmeijer ◽  
Gerben Ruessink ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Large Scale ◽  
Water Movement ◽  
Small Scale ◽  
Sand Transport ◽  
Influence Model ◽  
The North ◽  
Ebb Tidal Delta ◽  
Transport Patterns ◽  
Set Up

Bedform-related roughness affects both water movement and sediment transport, so it is important that it is represented correctly in numerical morphodynamic models. The main objective of the present study is to quantify for the first time the importance of ripple- and megaripple-related roughness for modelled hydrodynamics and sediment transport on the wave- and tide-dominated Ameland ebb-tidal delta in the north of the Netherlands. To do so, a sensitivity analysis was performed, in which several types of bedform-related roughness predictors were evaluated using a Delft3D model. Also, modelled ripple roughness was compared to data of ripple heights observed in a six-week field campaign on the Ameland ebb-tidal delta. The present study improves our understanding of how choices in model set-up influence model results. By comparing the results of the model scenarios, it was found that the ripple and megaripple-related roughness affect the depth-averaged current velocity, mainly over the shallow areas of the delta. The small-scale ripples are also important for the suspended load sediment transport, both indirectly through the affected flow and directly. While the current magnitude changes by 10–20% through changes in bedform roughness, the sediment transport magnitude changes by more than 100%.

Wave-Induced Current in a Seakeeping Basin

2017 ◽  
Author(s):  
Sanne van Essen ◽  
Wim Lafeber
Keyword(s):  
Large Scale ◽  
Wave Generation ◽  
Stokes Drift ◽  
Induced Current ◽  
Added Resistance ◽  
End Effects ◽  
Wave Basin ◽  
Current Drag ◽  
Wave Induced ◽  
Small Models

During tests in MARIN’s wave basins, it was observed that large-scale current patterns may develop under the influence of wave generation and absorption. The velocity of these currents is very low, so they generally do not influence the behaviour of models. However, for specific experiments at low speeds — wave added resistance tests with small models or current drag tests — a residual current may influence the results significantly. A good understanding of the residual circulation in a wave basin is essential to improve the quality of the tests performed. The wave-induced current patterns were observed during tests in MARIN’s Seakeeping and Manoeuvring Basin (SMB). The patterns may develop in several ways under the influence of waves in a basin. End effects of Stokes drift (mass transport due to second-order wave effects) can play a role, as the water has to return at the end of the basin. The SMB has the capability to generate oblique waves. It therefore has a wave-damping beach along two sides of the basin. Similar to ‘real’ beaches, they may cause alongshore currents and rip currents under the influence of oblique and perpendicular waves respectively. During the tests, floaters in the form of oranges were distributed in the basin after wave generation. They were tracked using a camera system. The images were processed such that the surface current patterns in the basin were visualized, and an estimate of the velocities was obtained. Additional local acoustic current meter measurements were used to check the order of magnitude of these velocities. Based on these tests, it was concluded that different patterns may occur in the basin, with the largest velocities after oblique wave generation. Typical surface velocities are in the order of 1 to 2 cm/s, non-uniformly distributed over the basin. Due to this non-uniformity and because decay is slow (memory effects), very sensitive added resistance and current drag tests may have to be corrected for a measured current velocity in the future.

scholarly journals Beach Profile Evolution towards Equilibrium from Varying Initial Morphologies

2019 ◽  
Vol 7 (11) ◽  
pp. 406 ◽  
Author(s):  
Sonja Eichentopf ◽  
Joep van der Zanden ◽  
Iván Cáceres ◽  
José M. Alsina
Keyword(s):  
Sediment Transport ◽  
Large Scale ◽  
Intermediate Energy ◽  
Swash Zone ◽  
Energy Profile ◽  
Beach Profile ◽  
Wave Condition ◽  
Wave Energy Dissipation ◽  
Transport Patterns ◽  
In The Beginning

The evolution of different initial beach profiles towards the same final beach configuration is investigated based on large-scale experimental data. The same wave condition was performed three times, each time starting from a different initial profile morphology. The three different initial profiles are an intermediate energy profile with an offshore bar and a small swash berm, a plane profile and a low energy profile with a large berm. The three cases evolve towards the same final (equilibrium) profile determined by the same wave condition. This implies that the same wave condition generates different sediment transport patterns. Largest beach changes and differences in hydrodynamics occur in the beginning of the experimental cases, highlighting the coupling between morphology and hydrodynamics for beach evolution towards the same profile. The coupling between morphology and hydrodynamics that leads to the same final beach profile is associated with differences in sediment transport in the surf and swash zone, and is explained by the presence of bar and berm features. A large breaker bar and concave profile promote wave energy dissipation and reduce the magnitudes of the mean near-bed flow velocity close to the shoreline limiting shoreline erosion. In contrast, a beach profile with reflective features, such as a large berm and a small or no bar, increases negative velocity magnitudes at the berm toe promoting shoreline retreat. The findings are summarised in a conceptual model that describes how the beach changes towards equilibrium from two different initial morphologies.

scholarly journals LONG TERM PERFORMANCE OF A SUBMERGED COASTAL CONTROL STRUCTURE: A CASE STUDY OF THE NARROWNECK MULTI-FUNCTIONAL ARTIFICIAL REEF

2012 ◽  
Vol 1 (33) ◽  
pp. 54 ◽  
Author(s):  
Angus Jackson ◽  
Rodger Tomlinson ◽  
Bobbie Corbett ◽  
Darrell Strauss
Keyword(s):  
Large Scale ◽  
Control Point ◽  
Artificial Reef ◽  
Beach Erosion ◽  
Gold Coast ◽  
Storm Events ◽  
Marine Habitat ◽  
Submerged Breakwater ◽  
Long Term Performance ◽  
Term Performance

In response to the increasing occurrences of beach erosion along Surfers Paradise and Main Beaches - Gold Coast, Australia, the Northern Gold Coast Beach Protection Strategy [NGCBPS] was developed to widen the beach by 20-30m as well as improving surfing conditions as a secondary objective. The strategy, implemented in 1999- 2000, involved large-scale beach nourishment and construction of a submerged breakwater “reef” to act as a control point at Narrowneck. Construction of the reef involved innovative filling and placement methods using very large sand filled geotextile containers coupled with significant advances with regards to design of the geotextile material and containers. In the 11 years since construction, there has been substantial monitoring of the project since its completion in late 2000 including: - video imaging using webcams; hydrographic and beach surveys; aerial and oblique photography; surf and surf safety observations and GPS surfing track plots; and geotextile container condition and stability. This paper presents an update on the performance of the reef over the last four years. In particular, the response of the structure and the shoreline to a series of major storm events in 2009 has been examined. The results have shown that the erosion caused by these major events was accommodated within the wider beach created in 1999. Over the next 2 years there was a gradual recovery in the lee of the reef with a subtle groyne effect resulting in an even larger increase in the width of the updrift beach. A detailed underwater condition survey was also undertaken in 2011, to determine changes in the condition of the geotextile containers. This revealed a number of containers missing or damaged, and that seaward containers were covered by sand. The marine habitat which has been a feature of the reef has been impacted by the increased coverage of sand, but still shows high abundance and biodiversity.

scholarly journals Morphodynamic modelling for the entire German Bight: an initial study on model sensitivity and uncertainty

2014 ◽  
Vol 39 ◽  
pp. 61-68 ◽  
Author(s):  
A. Plüß ◽  
F. Kösters
Keyword(s):  
Sediment Transport ◽  
German Bight ◽  
Large Scale ◽  
Morphological Changes ◽  
Initial Study ◽  
Model Sensitivity ◽  
Morphodynamic Modelling ◽  
Transport Patterns

Abstract. Morphodynamic modelling of coastal seas and estuaries for large-scale and long-term applications is strongly affected by parameter sensitivity of process-based models. Moreover, the comparison of data-based methods with numerical model results is limited by uncertainties in measurements. These drawbacks can be partly overcome by a multi-model approach (MMA). In a case study to assess long-term sediment transport and morphodynamic processes for the German Bight, the AufMod research project applies two different methods for process-based modelling: UnTRIM-SediMorph and DELFT3D. Model sensitivity is illustrated in terms of different morphological changes for diverse porosity values. As a first step, discrepancies between individual methods are shown based on resulting sediment transport patterns.

scholarly journals HYDRAULIC APPROACH TO SHORELINE CHANGE DUE TO SUBMERGED BREAKWATER

2020 ◽  
pp. 40
Author(s):  
Inho Kim ◽  
Hyungseok Lee ◽  
Jinhoon Kim ◽  
Sungyeol Chang
Keyword(s):  
Numerical Analysis ◽  
Shoreline Change ◽  
Beach Erosion ◽  
Rip Current ◽  
Rip Currents ◽  
Induced Current ◽  
Beach Profile ◽  
Submerged Breakwater ◽  
Sand Movement ◽  
Wave Induced

The items of investigation include wave induced current, wave height, beach profile, shoreline change, etc. The investigation has been performed seasonally. After the construction of submerged breakwaters, a tombolo was generated behind the submerged breakwaters. This caused beach erosion in the nearby areas. Rip currents are mainly generated near submerged breakwaters, which plays a role in the transportation of sand in the offshore direction. In order to analyze the sand movement, numerical analysis was conducted. The analysis indicated that a strong rip current is generated near submerged breakwaters.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/5p2wiNSMKlM

scholarly journals MODELING MORPHOLOGICAL EVOLUTION IN THE VICINITY OF COASTAL STRUCTURES

2011 ◽  
Vol 1 (32) ◽  
pp. 68 ◽  
Author(s):  
Pham Thanh Nam ◽  
Magnus Larson ◽  
Hans Hanson
Keyword(s):  
Sediment Transport ◽  
Large Scale ◽  
Transport Model ◽  
Morphological Evolution ◽  
Transformation Model ◽  
Quality Data ◽  
Wave Transformation ◽  
Random Wave ◽  
Army Corps ◽  
Wave Induced

A numerical model of beach topography evolution was developed. The model includes five sub-models: random wave transformation model, surface roller model, wave-induced current model, sediment transport model, and morphological change model. The model was validated by two unique high-quality data sets obtained from experiments on the morphological impact of a detached breakwater and a T-head groin in the basin of the Large-scale Sediment Transport Facility (LSTF) at the US Army Corps of Engineer Research and Development Center in Vicksburg, Miss. The simulations demonstrated that the model well reproduced the wave conditions, wave-induced currents, and morphological evolution in the vicinity of the structures.

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