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 Analysis of Rip Current Characteristics Using Dye Tracking Method

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 719
Author(s):  
Hyun Dong Kim ◽  
Kyu-Han Kim
Keyword(s):  
Surf Zone ◽  
Breaking Waves ◽  
Rip Current ◽  
Rip Currents ◽  
Induced Current ◽  
Tracking Method ◽  
Survey Techniques ◽  
Current Characteristics ◽  
Bed Material ◽  
Wave Induced

Rip currents are strong water channels flowing away from the shoreline. They can occur on any shore with breaking waves. Rip currents play a significant role in changing the topography of shallow water regions by transporting large amounts of bed material offshore. Moreover, they pose a significant danger for people living in nearshore zones and surfers and cause hundreds of deaths annually worldwide. Therefore, rip current generation characteristics have been investigated to prevent casualties. In this study, a GPS drifter survey was chosen as the investigation method; however, a few drawbacks were discovered, such as low accuracy due to the GPS drifter becoming trapped in the surf zone. Therefore, drones and dyes were used to overcome the drawbacks of drifter methods. The results of dye tracking and the 3D wave-induced current numerical simulation were compared; the velocity and formation of the rip current were found to be relatively similar. With the technological advancements and invention of new survey equipment, the survey techniques also evolve, and this paper shows that the disadvantages of the GPS-based Lagrangian method can be overcome using a dye-mounted drone, which observes the rip current easily and accurately.

scholarly journals WAVE INDUCED CURRENT MONITORING USING UAV-BASED PHOTOGRAMMETRY

2018 ◽  
pp. 6
Author(s):  
Bumshick Shin ◽  
Kyu-Han Kim
Keyword(s):  
Image Analysis ◽  
Spatial Information ◽  
Low Cost ◽  
Rip Currents ◽  
Induced Current ◽  
Wave Runup ◽  
Large Area ◽  
High Position ◽  
Remote Sensing Techniques ◽  
Wave Induced

In recent years, due to the development of hardware and video image processing technology, image analysis technique using a wide coastal coastline, it made it possible to analyze the wave runup and swash, current and so on. However, in order to obtain the image information of a large area requires a high-resolution imaging at a high position, however, to the recording technique used in the past, there is a limit of height and resolution. Thus, recently, on the basis of remote sensing techniques, or build spatial information technology using UAV (Unmanned Aerial Vehicle) system, and the research and utilization in various fields it increased. Small UAV platforms is becoming low-cost, miniaturized hyperspectral imaging technology. The direct measurement of wave induce current is tested using image analysis techniques using sea dye maker and UAV. Specially, rip currents are approximately shore normal seaward flows which are strong, localized and rather narrow. In this method, UAV at a region with frequent wave induced current occurrence, and images are continuously obtained in real time. This research investigates the development of wave induced currents using images in East coast of Korea.

scholarly journals COUNTERMEASURE AGAINST EROSION BEHIND SUBMERGED BREAKWATER DUE TO SEA LEVEL RISE

2018 ◽  
pp. 62
Author(s):  
Yoshiaki Kuriyama ◽  
Masayuki Banno
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Land Subsidence ◽  
West Coast ◽  
Shoreline Change ◽  
Sandy Beaches ◽  
Beach Erosion ◽  
Relative Sea Level ◽  
Submerged Breakwater ◽  
Relative Sea Level Rise

Submerged breakwaters are considered to be preferable countermeasures against beach erosion where the availability of sediments for nourishment is limited and tourism is prevalent because submerged breakwaters do not interfere with the view of the horizon from the shore. However, sandy beaches protected by submerged breakwaters are assumed to be vulnerable to relative sea level rise (SLR) and land subsidence because the crests of submerged breakwaters are below sea level. Kuriyama and Banno (2016) numerically predicted the future shoreline change under SLR and land subsidence on the Niigata West coast in Japan, which is protected by submerged breakwaters. The prediction showed that the shoreline will retreat 60 m over the next 100 years. In this study, we investigated the effects of countermeasures against the erosion due to SLR and land subsidence.

scholarly journals RIP - CURRENTS

1972 ◽  
Vol 1 (13) ◽  
pp. 32
Author(s):  
Edward K. Noda
Keyword(s):  
Field Data ◽  
Bottom Topography ◽  
Circulation Pattern ◽  
Rip Current ◽  
Rip Currents ◽  
Nearshore Zone ◽  
Circulation Patterns ◽  
Hydrodynamic Processes ◽  
Wave Induced ◽  
Current Circulation

The generation and stabilization of rip - current circulation patterns is considered herein. An analytic model is developed to simulate the wave hydrodynamic processes in the nearshore zone, strongly influenced by the local bottom topography. The wave induced nearshore circulation pattern is computed and the results compared to prototype field data.

scholarly journals A FIELD AND NUMERICAL STUDY INTO RIP CURRENTS IN WIND-SEA DOMINATED ENVIRONMENTS

2012 ◽  
Vol 1 (33) ◽  
pp. 36
Author(s):  
Gundula Winter ◽  
Ap Van Dongeren ◽  
Matthieu De Schipper ◽  
Jaap Van Thiel de Vries
Keyword(s):  
Surf Zone ◽  
Numerical Study ◽  
Warning System ◽  
Rip Current ◽  
Rip Currents ◽  
Mean Flow ◽  
Flow Properties ◽  
Wind Sea ◽  
Wave Induced ◽  
Made In

Rip currents are wave-induced and off-shore directed flows which occur frequently in the surf zone and can pose a serious threat to swimmers. While the behaviour of rip currents has been studied in swell-dominated environments, less is known about their characteristics in wind-sea dominated environments. This study aims to improve the knowledge on rip currents in these environments such as the Dutch coast. In a field campaign at Egmond aan Zee (The Netherlands), Lagrangian velocities in the surf zone were measured with drifter floats. An extensive dataset of rip current measurements was collected from which parameters that initiate rip currents and affect their mean flow properties were identified. Numerical simulations with XBeach aided to understand and confirm the observations made in the field. A reduction of the hydrodynamic parameters along with simplification of the bathymetry in the model allowed for identification of the governing rip current parameters, which can be the basis for a warning system.

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 Littoral drift analysis based on long-term observation of mesotidal beach profile in Kuta Beach, Bali for coastal retreat assessment

2021 ◽  
Vol 925 (1) ◽  
pp. 012040
Author(s):  
R. R. Rahmawati ◽  
A. H.S. Putro ◽  
J.L. Lee
Keyword(s):  
Temporal Variability ◽  
Shoreline Change ◽  
Transport Processes ◽  
Beach Erosion ◽  
Observation Data ◽  
Beach Profile ◽  
Littoral Drift ◽  
Shoreline Changes ◽  
Coastal Retreat

Abstract The beach profile survey in the intertidal zone is crucial for a temporal variability study of shoreline and beach profile change for coastal management. The combination of numerical modelling and field data has proven to be successful in identifying the primary hydrodynamic and sediment transport processes such as littoral and cross-shore drift. Those parameters are relevant to the sandbar migration process and shoreline changes. The purpose of the present study is to analyse the littoral drift that caused temporal variability shoreline change in mesotidal beach for coastal retreat mitigation. Beach profile data of Kuta Beach was analyzed by 7 years of long-term field observation data both east monsoon and west monsoon situation. The shoreline definition used mean sea level (MSL)1.3 m and high water level (HWL) 2.6 m as reference. By using the MeEPASoL program as a graphical user interface program, shoreline changes converging to an equilibrium state can be simulated by taking into account the existing breakwater. Temporal shoreline position resulting from littoral drift and beach width change from its initial position is estimated for coastal erosion analysis. The result showed that dominantly, the littoral drift pattern moved from south to north. Furthermore, this study can be used in the process of identifying the primary hydrodynamic analysis in erosion disaster management as assessment of the beach erosion.

scholarly journals RIP CURRENTS AND THEIR CAUSES

1978 ◽  
Vol 1 (16) ◽  
pp. 83 ◽  
Author(s):  
Robert A. Dalrymple
Keyword(s):  
Wave Height ◽  
Bottom Topography ◽  
High Energy ◽  
Rip Current ◽  
Rip Currents ◽  
Coastal Structures ◽  
Submarine Canyons ◽  
Set Up ◽  
Wave Induced ◽  
Made In

"The outworn dogmas of science seem to be particularly concentrated in the discussions of the ocean in geology books". Beginning with this controversial statement, F. P. Shepard in 1936 tried to lay to rest the concept of the undertow, which had been debated in the pages of Science for over a decade. At the same time, he introduced the term, rip current, to describe the rapidly seaward-flowing currents, which were well-known to lifeguards at that time, as these currents were responsible for carrying swimmers offshore at frightening speeds. Subsequent studies by Shepard and his colleagues (Shepard, Emery and LaFond, 1941; Shepard and Inman, 1950a, 1950b) showed that rip currents (1) are caused by longshore variations in incident wave height, (2) are often periodic in both time and in the longshore direction and (3) increase in velocity with increasing wave height. The major reason put forth to explain the variation in wave height was the convergence or divergence of wave rays over offshore bottom topography (such as submarine canyons) or the forced wave height variability caused by coastal structures, such as jetties. McKenzie (1958) and Cooke (1970) in their studies corroborated the findings of the Scripps Institution of Oceanography researchers and also pointed out the persistence of rip currents (once high energy waves in a storm had caused rip channels to be cut into the bottom) after the storm had abated. In fact it appears that on coastlines which are affected by major storms which build offshore bars, that the nearshore circulation may be dominated by the storm-1-induced bottom topography for long afterwards. The researchers up to the late 1960's who attempted to theoretically model rip currents knew the importance of longshore wave height variability and the wave-induced set-up in the formation of rip currents, but it was not until Longuet-Higgins and Stewart (e.g., 1964) codified the wave momentum flux tensor that great strides were made in providing models for rip currents. This paper is intended to categorize and review the more recent theories for rip current generation and to discuss a simple model for rip currents on barred coastlines.

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