The Rate of Longshore Sediment Transport and Beach Erosion Control

1982 ◽  
Author(s):  
Yoshito Tsuchiya
Keyword(s):  
Sediment Transport ◽  
Erosion Control ◽  
Beach Erosion ◽  
Longshore Sediment Transport

scholarly journals THE RATE OF LONGSHORE SEDIMENT TRANSPORT AND BEACH EROSION CONTROL

1982 ◽  
Vol 1 (18) ◽  
pp. 81
Author(s):  
Yoshito Tsuchiya
Keyword(s):  
Sediment Transport ◽  
Incident Angle ◽  
Bottom Topography ◽  
Erosion Control ◽  
Breaking Waves ◽  
Beach Erosion ◽  
Wave Power ◽  
Total Rate ◽  
Longshore Sediment Transport ◽  
New Formulation

The main purpose of this paper is to propose an ideal methodology for beach erosion control from the viewpoint of controlling the total rate of longshore sediment transport. For this, a new formulation of the rate of longshore sediment transport is made. The total rate is directly proportional to the longshore component of wave power in field coasts, but not in laboratory ones. How to control the total rate of longshore sediment transport is considered. There are two ways applicable for practical purposes. The first is to decrease the breaker depth by changing the bottom topography, and the second to decrease the incident angle of breaking waves by changing either the bottom topography or the inclination of shoreline to the incidence of predominant waves. Two typical, but ideal examples are explained for beach erosion control by this methodology.

scholarly journals STORM-INDUCED EROSION OF NOTSUKEZAKI SAND SPIT, JAPAN

2018 ◽  
pp. 79
Author(s):  
Seiya Itori ◽  
Kazuki Yagisawa ◽  
Takayuki Sasaki ◽  
Ryo Yamaguchi ◽  
Nobuhisa Kobayashi
Keyword(s):  
Sediment Transport ◽  
Beach Erosion ◽  
Dredged Sediment ◽  
Longshore Sediment Transport ◽  
Sand Spit ◽  
The 1960S

The hook-shaped sand spit at Notsukezaki is the longest (26 km) spit in Japan. The spit is located down-drift of the Shibetzu River. Beach erosion became severe in the 1960s after the construction of the Shibetsu Port updrift of the sand spit. The breakwater of the port intercepted longshore sediment transport. The deposited sediment up to 20,000 m3 has been dredged every year. The dredged sediment has been placed on Sections I and II on the spit. In addition, 39 groins of 35 m length were constructed from 1995 to 2015 in order to protect fishing facilities on the spit.

scholarly journals A HYBRID MODEL OF SWASH-ZONE LONGSHORE SEDIMENT TRANSPORT ON REFLECTIVE BEACHES

2011 ◽  
Vol 1 (32) ◽  
pp. 29
Author(s):  
Angela Wenping Jiang ◽  
Michael Hughes ◽  
Peter Cowell ◽  
Angus Gordon ◽  
Juan Carlos Savioli ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Laboratory Data ◽  
Beach Erosion ◽  
Test Model ◽  
Swash Zone ◽  
Littoral Drift ◽  
Hybrid Modelling ◽  
Longshore Sediment Transport ◽  
Modelling Approach ◽  
Mike 21

The hydrodynamics and sediment transport in the swash zone is currently outside the domain of coastal-area models, which is a significant limitation in obtaining littoral sediment-transport estimates, especially on steep reflective beaches where the waves practically break on the beachface. In this study, an existing process-based coastal model (MIKE 21) is combined with a theoretical derivation of swash processes, resulting in an innovative hybrid modelling approach that is capable of estimating longshore sediment transport in the swash zone. The method relies upon estimation of swash hydrodynamics from an extended ballistic swash model with friction included. The terminal bore and other incident wave properties were computed from the output of a spectral-wave model (MIKE 21 SW). The Bagnold-type equation was applied to estimate gross transport volumes and the longshore component was computed for the sand volume displaced during the up-rush. The newly developed hybrid modelling approach was applied to Jimmys beach, a steep reflective beach (D50 = 0.3 mm, gradient=0.1) along the northern shoreline of Port Stephens, Australia. The model results yield the alongshore swash transport pathways and the indicative transport volumes. A point of divergence is identified at the beach erosion area, which is of critical importance in terms of shoreline erosion and management. The preliminary results suggest that swash-zone transport can account for a large percentage of the total littoral drift for such beaches. However, further field or laboratory data are required to test model utility, as well as to tune calibration parameters based on the site-specific conditions.

STUDY ON LONGSHORE SEDIMENT TRANSPORT USING CIRCULAR WAVE BASIN

2019 ◽  
Vol 75 (2) ◽  
pp. I_625-I_630
Author(s):  
Naoki AKITA ◽  
Risa KATO ◽  
Hoang Hai DONG ◽  
Tomoaki NAKUMURA ◽  
Norimi MIZUTANI
Keyword(s):  
Sediment Transport ◽  
Longshore Sediment Transport ◽  
Wave Basin

scholarly journals Modelling of sediment transport and morphological evolution under the combined action of waves and currents

Ocean Science ◽  
2017 ◽  
Vol 13 (5) ◽  
pp. 673-690 ◽  
Author(s):  
Guilherme Franz ◽  
Matthias T. Delpey ◽  
David Brito ◽  
Lígia Pinto ◽  
Paulo Leitão ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Morphological Changes ◽  
Morphological Evolution ◽  
Research Effort ◽  
Beach Erosion ◽  
Model Complexity ◽  
Invariant Equilibrium ◽  
Waves And Currents ◽  
Combined Action ◽  
Modelling System

Abstract. Coastal defence structures are often constructed to prevent beach erosion. However, poorly designed structures may cause serious erosion problems in the downdrift direction. Morphological models are useful tools to predict such impacts and assess the efficiency of defence structures for different scenarios. Nevertheless, morphological modelling is still a topic under intense research effort. The processes simulated by a morphological model depend on model complexity. For instance, undertow currents are neglected in coastal area models (2DH), which is a limitation for simulating the evolution of beach profiles for long periods. Model limitations are generally overcome by predefining invariant equilibrium profiles that are allowed to shift offshore or onshore. A more flexible approach is described in this paper, which can be generalised to 3-D models. The present work is based on the coupling of the MOHID modelling system and the SWAN wave model. The impacts of different designs of detached breakwaters and groynes were simulated in a schematic beach configuration following a 2DH approach. The results of bathymetry evolution are in agreement with the patterns found in the literature for several existing structures. The model was also tested in a 3-D test case to simulate the formation of sandbars by undertow currents. The findings of this work confirmed the applicability of the MOHID modelling system to study sediment transport and morphological changes in coastal zones under the combined action of waves and currents. The same modelling methodology was applied to a coastal zone (Costa da Caparica) located at the mouth of a mesotidal estuary (Tagus Estuary, Portugal) to evaluate the hydrodynamics and sediment transport both in calm water conditions and during events of highly energetic waves. The MOHID code is available in the GitHub repository.

Revisiting the derivation of bulk longshore sediment transport rates using meta-heuristic algorithms

2021 ◽  
Vol 69 ◽  
Author(s):  
Zahra Gholami ◽  
Kamran Lari ◽  
Abbasali Aliakbari Bidokhti ◽  
AmirHosein Javid
Keyword(s):  
Sediment Transport ◽  
Heuristic Algorithms ◽  
Longshore Sediment Transport
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