Numerical Model of 3d Morphodynamic After Offshore Nourishment

et al. 2012

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The objective of study is to develop a coastal area model for sandy beach with shore reef such as non-eroded hard bottom. The morphodynamics with exposure and bury of the shore reef are reproduced by advection and diffusion model for suspended sediment concentration. Firstly, model tests associated with sandy beaches with a detached breakwater and groins were carried out in order to investigate the performance of the presented model. Secondly, the presented model was applied to a filed site with both shore reef and sandy beach, the applicability of the model was investigated and discussed.Keywords: morphodynamics; sediment transport; beach evolution model;shore-reef INTRODCUTIONMany morphodynamic models for predicting three-dimensional (3D) deformation of sandy beach, which is so called "Coastal Area Model", have been proposed (e.g. Watanabe et al.,1986 ; de Vriend et al,1993;Johnson et al.,1994;Zyserman et al., 2002;Lesser et al. ,2004;Kuroiwa et al.,2004). The predictive 3D models are very useful to predict beach evolution due to construction of coastal structures such as detached breakwaters, groins and so on. In general, actual sandy beaches consist of various grain size, or include non-eroded hard bottom such as shore reef. The actual mophodynamics are extremely complex. Therefore, the development and modification of the coastal area model have been still proceeded. Some models for considering the effect of grain size of bed material were proposed(e.g. Kuroiwa et al.,2006), and for sandy beach with non-eroded hard bottom have also presented(e.g. Ikeno et al.,2004; Hans et al.,2005).Sakenotsu fishing port, Tottori, Japan, facing the Sea of Japan, has been suffered from sedimentation at the entrance and channel of the fishery port. Sakenotsu fishing port is surrounded shore reef, which is non-eroded hard bottom, and adjacent to Mizushiri sandy beach Therefore, the phenomena of the sediment transport due to waves and nearshore currents may be influenced by the existence of the shore reef. Although several countermeasures such as the extension of offshore breakwaters have been performed, the dredging work of bed material that has accumulated in the harbor entrance still has been carrying out. The accretion mechanism should be clarified and some new countermeasures against the sedimentation problem are needed. In order to propose some countermeasures, a reliable 3D morphodynamic model considering the influence of the hard bottom, which is the phenomena of the exposure and burying of the hard bottom due to drifting sand, is needed.The purpose of this study is to develop a numerical model for predicting three-dimensional beach evolution to sandy beach with hard sea bottom such as shore reef. In this paper, at first, in order to investigate the influence of the hard bottom and the performance of the presented model, some model tests were carried out. Furthermore, in order to investigate the applicability of the model, the developed model was applied to the 3D morphodynamics around Sakenotsu fishing port. NUMERICAL...

Section: Numerical Modelmentioning

confidence: 99%

Three-Dimensional Morphodynamic Model to Sandy Beach With Non-Eroded Hard Bottom

Hasegawa¹,

et al. 2012

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“…In this study, Multi-directional random wave model based on the wave action balance equation proposed by Mase et al(2004) was newly added the previous 3D model presented by Kuroiwa et al(2010). The presented model in this study consists of four modules as shown in Fig.…”

Section: Numerical Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Many three-dimensional beach evolution models have been proposed and then applied to practical evaluation of the construction of coastal structures, the accretion problems of the navigation channel of ports and so on. We have develop a coastal area model with shoreline change based on the quasi-three dimensional (Q-3D) nearshore current model (Kuroiwa et al, 2004), and applied to 3D morphodynamics around river-mouth (Kuroiwa et al,2008) and after shoreface nourishments (Kuroiwa et al,2010). However, the hydrodynamic module in the previous models, which is based on the wave 1 Tottori University, Department of Civil Engineering, 4-101,Koyama,Tottori,680-8552, Japan 2 National Water Resource Center, Coastal Research Institute, 15 El-Pharaana St. 21514, Alexandria, Egypt 3 Tottori University, Department of Civil Engineering, 4-101,Koyama,Tottori,680-8552, Japan 4 Mikuniya Corporation, 3-1-10, Naniwa-ku, Saiwai-chou, Osaka, 556-0021,Japan 5 Disaster Prevention Research Institute, Kyoko University, Gokasho,Uji, Kyoto, 611-0011, Japan 6 Department of Environmental Engineering, the Islamic University of Gaza, Palestine COASTAL ENGINEERING 2012 2 energy balance equation and the Q-3D nearshore current model, was not considering the wave-current interaction.…”

Section: Introductionmentioning

confidence: 99%

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A Coastal Area Model Considering Wave-Current Interaction and Its Application to Wide-Crested Submerged Breakwater

Seif²,

et al. 2012

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This study is concerned with development of a 3D morphodynamic predictive model for considering wave-current interaction by using wave action balance equation. The developed model was applied to model tests associated with a detached breakwater and wide-crested submerged breakwaters, and the influences of strong currents around the structures into wave height distribution and bathymetry change were investigated. Furthermore, the morphodynamics around the artificial reefs in the Uradome Beach, Tottori, Japan, was computed. From the computed results, a large scour hole due to strong rip-currents in the opening of the reefs was reproduced. The applicability of the model was confirmed. Keywords: morphodynamic; submerged breakwater; rip-current; numerical simulation INTRODUCTIONWide-crested submerged breakwater, which is so-called "Artificial reef", is an effective structure for preventing sandy beach erosion due to wave and nearshore current actions, and for the landscape of sea-view in front of sandy beaches, especially Japan. Uradome beach in Tottori, which is a pocket beach facing the Sea of Japan, has been suffered from beach erosion. In order to prevent the beach erosion, two artificial reefs with the crest depth of 2m and the crest width of 40m were constructed in 1996, as shown in Fig.1. However, very large scour around a gap of the artificial reefs occurred due to strong rip currents at the gap, as shown in Fig. 2. Therefore, in order to take reliable countermeasures for preventing the large scour, maintaining stability of the submerged breakwaters, and evaluating the morphodynamics around the breakwaters, a coastal area model for considering the hydrodynamic in wave-current coexistence field such as the strong current generated at the gap is also required. Many three-dimensional beach evolution models have been proposed and then applied to practical evaluation of the construction of coastal structures, the accretion problems of the navigation channel of ports and so on. We have develop a coastal area model with shoreline change based on the quasi-three dimensional (Q-3D) nearshore current model (Kuroiwa et al., 2004), and applied to 3D morphodynamics around river-mouth (Kuroiwa et al.,2008) and after shoreface nourishments (Kuroiwa et al.,2010). However, the hydrodynamic module in the previous models, which is based on the wave 1 Tottori University, Department of Civil Engineering, 4-101,Koyama,Tottori,680-8552, Japan 2 National Water Resource Center, Coastal Research Institute, 15 El-Pharaana St. 21514, Alexandria, Egypt 3 Tottori University, Department of Civil Engineering, 4-101,Koyama,Tottori,680-8552, Japan 4 Mikuniya Corporation, 3-1-10, Naniwa-ku, Saiwai-chou, Osaka, 556-0021,Japan 5 Disaster Prevention Research Institute, Kyoko University, Gokasho,Uji, Kyoto, 611-0011, Japan 6 Department of Environmental Engineering, the Islamic University of Gaza, Palestine COASTAL ENGINEERING 2012 2 energy balance equation and the Q-3D nearshore current model, was not considering the wave-current interaction. Taji...

“…The developed coastal area model was based on the hybrid model proposed by Kuroiwa et al (2006Kuroiwa et al ( ,2010. The coastal area model presented in this study consists of three modules; 1) a wave module, 2) a nearshore current module, 3) a sediment transport and a water depth change evolution module, as shown in Fig.1.…”

Section: Numerical Modelmentioning

confidence: 99%

A Coastal Area Model Considering Sand Nourishment Process

Shibutani

et al. 2014

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This paper presents a 3 D morphodynamic model with shoreline change based on quasi-3D nearshore current model. In this model, sand nourishment process with sand dredging and charging was newly considered. First, in order to investigate the performance the present model, it is applied to the prediction of 3D beach evolution with sand bypassing system around a model port and sand recycling system between two groins. Secondly, the developed model was applied to morphodynamics after sand nourishment in a sand recycle project conducted Kaike Coats, Tottori,Japan. Finally, the applicability of the model was investigated and discussed.