Topic
Groyne
About: Groyne is a research topic. Over the lifetime, 397 publications have been published within this topic receiving 4549 citations. The topic is also known as: groin & Breakwater.
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06 Sep 2006
TL;DR: In this article, the authors investigated the partial cross-sections of the East Frisian tidal inlets in terms of the modified hydrodynamical conditions and showed that partial crosssections in Harle inlet show a retarded adjustment to the modified equilibrium conditions.
Abstract: The East Frisian tidal inlets tend to migrate with the prevailing eastward drift in the southern North Sea. For Harle inlet eastward migration was accelerated by the adaption of tidal basin and inlet to the resedimentation of a medieval storm surge bay. To prevent further migration a large-scale groyne was built in the eastern part of Harle inlet between 1938 and 1940. Nowadays this structure still keeps the main channel in position and restricts the extent of a secondary channel. But in the last two decades redistribution of tidal gullies in the catchment area significantly increases the tidal prism of the secondary channel and accordingly its cross-section starts to expand. Investigation in light of empirical equilibrium conditions indicate that the partial cross-sections in Harle inlet show a retarded adjustment to the modified hydrodynamical conditions. But future adaptation of equilibrium conditions through further erosion of the secondary channel is anticipated.
26 Oct 2020
TL;DR: In this article, numerical simulations were carried out to determine differences in sea water level and flow velocity, for the two conditions with and without groyne, and it was concluded that the model with Groyne showed a higher flow velocity than the model without Groynes.
Abstract: The Puger Fish Landing Base is located on the southern coast of Java Island, so this port is directly facing the Indian Ocean. At the entrance and exit of the ship to the harbor a groin exists. The groin is located on the Puger River and faces the sea. The groyne is influenced by current and tidal patterns. The groyne was built in 2014, and then was cut. Based on this phenomenon, numerical simulations were carried out to determine differences in sea water level and flow velocity, for the two conditions with and without groyne. Bathymetry data obtained from BIG (Indonesian Geospatial Information Agency) was used for simulations. Tidal observations from previous studies were used to validate the model. Two scenario models with and without groynes were simulated. Spatial variations of flow velocity in the highest tides, minimum tides, and representative time steps for both cases were presented. It can be seen that with groyne, flow velocity was greater and more unstable than models without groyne. Based on the flow velocity pattern at the four observation points and water level, it is concluded that the model with groyne showed a higher flow velocity than the model without groyne.
03 Oct 2011
TL;DR: In this article, the authors examined the relationship between the exchange rate and the bed configuration of the cavity, and they found that the effect of bed shear stress on the cavity is very important.
Abstract: We can often see dead water zones composed of consecutive groynes in natural rivers. The groynes are generally constructed in the bank of actual rivers in order to navigate stream direction and to prevent bank erosion. Dead water zones such as side cavities are also observed in harbors of rivers, and it is well known that there are significant differences between streamwise velocities of the mainstream and the cavity zone. Of particular significance is that shear instability related to the velocity difference induces coherent horizontal vortex along the boundary of the mainstream and the cavity. Further, large-scale gyres are formed in the dead water zone which conveys suspended sediment from the main-channel, and local sedimentations are promoted in the cavity as shown in photo 1. So, it is necessary to reveal the hydrodynamic properties included with turbulence phenomena in order to control sedimentation reasonably. Akkerman et al.(2004) conducted the sensitivity analysis with a 1-dimensional morphodynamic model, and they discussed the several effects on sedimentation and flood water depth after the occurrence of groyne damage. Recently, permeable groynes are proposed to realize stable bed condition. For example, Kadota & Suzuki (2010) discussed experimentally effects of the permeability and the scales of the groynes and stone gabion in submerged and emerged flow conditions. Tominaga & Sakaki (2010) conducted ADV measurements around the permeable groynes in a natural river, and they evaluated distributions of bed shear stress accurately. In these cavities, not only sedimentation but also congestion of pollutants is often highlighted. It is thus very important to investigate mass & momentum exchanges between the main-channel and the side-cavity in river environment and hydraulic engineering. The above-mentioned horizontal gyres and coherent turbulent structures play significant roles on mass and momentum exchanges. Uijttewaal et al.(2001) measured distribution of dye concentration and pointed out that aspect ratio of side cavity has significant effects on exchange rate of mass between the mainstream and the dead water zone. Weitbrecht et al.(2007) have also conducted laboratory measurements, in which distribution of velocity components and dye were obtained. They examined the relation between the exchange rate and the bed configuration of the cavity.
01 Apr 2019
TL;DR: In this paper, the authors proposed a new type of coast protecting reinforced concrete blocks called Hexablock, which is characterized with higher wave suppression properties, interlocking capacity, stability on the slope and longer life time.
Abstract: A groyne is a shore protection structure built perpendicular to the shoreline of the coast (or river), over the beach and into the shoreface (the area between the nearshore region and the inner continental shelf), to reduce longshore drift and trap sediments. A groyne field or system is a series of groynes acting together to protect a beach. Concret is often used as construction material.On the basis of analysis of wave suppression efficiency and stability on the slope of more than one hundred existing shaped massives the new type of coast protecting reinforced concrete blocks – so called “Hexablock” (“Hexablock” was called because of its 6 facets) characterized with higher wave suppression properties, interlocking capacity, stability on the slope and longer life time is proposed.
14 Jul 2020
TL;DR: In this paper, the design drawings of sediment control buildings to reduce sedimentation / siltation from the direction of the sea into the river mouth, material structure costs and time schedule are presented.
Abstract: Coastal abrasion is one of the serious problems with shoreline change. In addition to natural processes, such as wind, currents and waves. One method for overcoming coastal abrasion is the use of coastal protective structures, where the structure functions as a wave energy damper at a particular location. Coastal buildings are used to protect the beach against damage due to wave and current attacks. Groyne is a coastal safety structure that is built protrudes relatively perpendicular to the direction of the coast, the importance of built coastal security with a groyne structure on the Jetis beach is as a flood control infrastructure that is as a final disposal of floods in the Ijo Watershed system, addressing coastal abrasion in detail. So we get the design drawings of sediment control buildings to reduce sedimentation / siltation from the direction of the sea into the river mouth, material structure costs and time schedule.