Effects of Submerged Breakwater on Hydrodynamics and Shoreline Change of the East Beach of Beidaihe, Bohai Bay, China

Kuang, Chunxiang; He, Lulu; Gu, Jie; Pan, Yi; Yang, Yin; Qiu, Ruofeng; Zhang, Jiabo

doi:10.2112/jcoastres-d-13-00173.1

Cited by 14 publications

(4 citation statements)

References 33 publications

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“…To avoid that and simplify calculation, we assume the enrockment only dissipates wave energy but does not affect tidal currents. This assumption can be justified by Kuang et al (2014) and Wen and Liu (2015), which have shown that the construction of low breakwaters does not significantly change the surrounding current field. In our model, waves with large wave height are dampened on reaching the enrockment owing to the limited water depth, while tidal currents go through directly as if the enrockment did not exist there.…”

Section: Simulations Of Upper-flat Enclosure and Lower-flat Enrockmentmentioning

confidence: 97%

The Impact of Reclamation on Tidal Flat Morphological Equilibrium

Zhong

2021

Front. Mar. Sci.

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Reclamation is one of the most prominent anthropogenic activities affecting tidal flat morphology and the related ecosystem service. Two representative types of reclamation are upper-flat enclosure and lower-flat enrockment. From a historical perspective, different type of reclamation was adapted in different areas in ancient China. As previous studies on reclamation are often site-specific, the reason that leads to such a difference is unclear. The intertidal dynamic equilibrium theory (DET) provides a comprehensive framework for this quest. Here, we extend the DET with additional effects of reclamation. A model based on DET (DET-ESTMORF) was applied to investigate the impact of reclamation on tidal flats. The model was validated by comparing our results against previous records and observations. Results show that both types of reclamation induce morphological adjustment by enhancing local accretion, which upset the previous equilibrium. Specifically, upper-flat enclosure drives tidal flats into evolution toward wave dominance, whereas lower-flat enrockment causes adjustment toward tidal dominance. Next, the impact of reclamation on tidal flats in different states (prograding or retreating) was investigated. We show that both enclosure and enrockment can induce accretion despite the varying wave climate and sediment supply, with the mean accretion rate raised by 1.8 cm/year and 1.2 cm/year, respectively. However, the resulting profiles are different in shape, especially on retreating flats. Finally, we point out that tidal range and sediment supply are the potential reasons affecting the choice of reclamation types in practices.

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Section: Simulations Of Upper-flat Enclosure and Lower-flat Enrockmentmentioning

confidence: 97%

The Impact of Reclamation on Tidal Flat Morphological Equilibrium

Zhong

2021

Front. Mar. Sci.

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“…Nearly 45% of the beaches in Qinhuangdao, approximately 80 km long, are not up to the standard of tourism due to shortened beach width, steepened slope, and coarser sand arising from chronic erosion. To tackle the erosion, the local government implemented a series of beach nourishment projects [37,[49][50][51][52] together with submerged breakwaters, artificial headlands, submerged sandbars. However, too many coastal protection structures that calm the hydrodynamic environment too much may cause water quality degeneration.…”

Section: Introductionmentioning

confidence: 99%

Morphodynamic Evolution of a Nourished Beach with Artificial Sandbars: Field Observations and Numerical Modeling

Kuang

Han

Zhang³

et al. 2021

JMSE

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Beach nourishment, a common practice to replenish an eroded beach face with filling sand, has become increasingly popular as an environmentally friendly soft engineering measure to tackle coastal erosion. In this study, three 200 m long offshore submerged sandbars were placed about 200 m from the shore in August 2017 for both coastal protection and beach nourishment at Shanhai Pass, Bohai Sea, northeastern China. A series of 21 beach profiles were collected from August 2017 to July 2018 to monitor the morphological changes of the nourished beach. Field observations of wave and tide levels were conducted for one year and tidal current for 25 h, respectively. To investigate the spatial-temporal responses of hydrodynamics, sediment transport, and morphology to the presence of three artificial submerged sandbars, a two-dimensional depth-averaged (2DH) multi-fraction sediment transport and morphological model were coupled with wave and current model and implemented over a spatially varying nested grid. The model results compare well with the field observations of hydrodynamics and morphological changes. The tidal range was around 1.0 m and the waves predominately came from the south-south-east (SSE) direction in the study area. The observed and predicted beach profiles indicate that the sandbars moved onshore and the morphology experienced drastic changes immediately after the introduction of sandbars and reached an equilibrium state in about one year. The morphological change was mainly driven by waves. Under the influences of the prevailing waves and the longshore drift toward the northeast, the coastline on the leeside of the sandbars advanced seaward by 35 m maximally while the rest adjacent coastline retreated severely by 44 m maximally within August 2017–July 2018. The model results demonstrate that the three sandbars have little effect on the tidal current but attenuate the incoming wave significantly. As a result, the medium-coarse sand of sandbars is transported onshore and the background silt is mainly transported offshore and partly in the longshore direction toward the northeast. The 2- and 5-year model simulation results further indicate that shoreline salient may form behind the sandbars and protrude offshore enough to reach the sandbars, similar to the tombolo behind the breakwater.

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“…The present measures against the scour can be mainly divided into two sections according to their principles: enhancing the stability of the erodible bed and modifying the flow structure. The former mainly includes toe protection [11], revetments [12, 13] and mattresses [14], while the latter includes groins [15, 16] and submerged breakwaters [17, 18]. However, many of the measures consolidating the stability of sediment on river bed and banks, like the revetments and mattresses, would lead to some environmental and ecological problems.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on bed pressure around geotextile mattress with sloping plate

Xie

Zhu

et al. 2019

PLoS ONE

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A geotextile mattress with sloping curtain is a newly proposed countermeasure against river and estuarine scour. In previous laboratory experiments, a geotextile mattress with sloping curtain was capable of protecting the bed downstream from scour and stimulating sediment deposition on both sides. However, the seepage scour under its geotextile mattress is inadequately researched at present. In this study, the Geotextile Mattress with Sloping Plate (GMSP) is proposed based on the simplification of the geotextile mattress with sloping curtain with the construction feasibility considered. A series of experiments was conducted to investigate the pressure distribution around the GMSP and the averaged seepage hydraulic gradient beneath its mattress. The results indicate remarkable pressure difference on two sides of the GMSP. The minimum bed pressure appears about 1.3 times the plate height downstream to the GMSP. The averaged seepage hydraulic gradient beneath the mattress increases with the sloping angle increasing from 35° to 60° in general. The averaged hydraulic gradient also ascends as the relative plate height increases, but reduces as the opening ratio increases at opening ratios greater than 0.143. The safety boundary for the averaged hydraulic gradient under the geotextile mattress of the GMSP could get much smaller than the critical hydraulic gradient of piping and can easily be overwhelmed. This phenomenon can mainly be attributed to the discontinuous contact between the mattress and the seabed. A suggestion for the parametric design of the GMSP is to extend the width of the mattress to reduce the risk of seepage failure.

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Effects of Submerged Breakwater on Hydrodynamics and Shoreline Change of the East Beach of Beidaihe, Bohai Bay, China

Cited by 14 publications

References 33 publications

The Impact of Reclamation on Tidal Flat Morphological Equilibrium

The Impact of Reclamation on Tidal Flat Morphological Equilibrium

Morphodynamic Evolution of a Nourished Beach with Artificial Sandbars: Field Observations and Numerical Modeling

Experimental study on bed pressure around geotextile mattress with sloping plate

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