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.

scholarly journals Coastline changes in relation to longshore sediment transport and human impact, along the shoreline of Kato Achaia (NW Peloponnese, Greece)

2001 ◽  
Vol 2 (1) ◽  
pp. 5 ◽  
Author(s):  
S. POULOS ◽  
G. CHRONIS
Keyword(s):  
Sediment Transport ◽  
Human Activities ◽  
Dynamic Equilibrium ◽  
Littoral Drift ◽  
Coastal System ◽  
Longshore Sediment Transport ◽  
Longshore Drift ◽  
Management Plans ◽  
Natural Equilibrium ◽  
Oblique Approach

Coastal configuration depends upon the equilibrium between available sediment budget and prevailing nearshore wave and current conditions. Human activities often disturb this natural equilibrium by altering the sources of beach material and littoral drift pattern. In the coastal zone of NW Peloponnese, an essentially tideless environment, the oblique approach of wind-induced waves implies an overall longshore drift from east to west. On an annual basis, the potential longshore sediment transport rates at the different sections of the study area (Kato Achaia) is estimated to vary between 0.02 10-3 m3/s and 5 103 m3/s and to fluctuate seasonally. The construction of a port and the extraction of aggregates from the R. Peiros have changed significantly the pattern of sediment transport inducing dramatic changes on coastline configuration; thus, the part of the coastline west to the port had retreated as much as 70 m eliminating a touristic beach, while the entrance of the port was silted inhibiting navigation. Coastal engineering measures, such as modification of port-breakwaters and construction of groins have had only minimal contribution in beach recovery. Hence, coastal management plans should consider this dynamic equilibrium and protect the natural coastal system from the arbitrary human activities.

scholarly journals Nearshore Waves and Littoral Drift Along a Micro-Tidal Wave-Dominated Coast Having Comparable Wind-Sea and Swell Energy

2020 ◽  
Vol 8 (1) ◽  
pp. 55
Author(s):  
Jesbin George ◽  
V. Sanil Kumar ◽  
R. Gowthaman ◽  
Jai Singh
Keyword(s):  
Sediment Transport ◽  
Wave Model ◽  
Model Data ◽  
Wave Direction ◽  
Littoral Drift ◽  
Relative Contribution ◽  
Wave Parameters ◽  
Longshore Sediment Transport ◽  
Wind Sea ◽  
Small Change

The nearshore wave characteristics and variations in littoral drift (longshore sediment transport; LST) are estimated based on different approaches for four years along the Vengurla coast, with comparable wind-sea and swell energy assessed. The waverider buoy-measured data at 15 m water depth is utilized as the input wave parameters along with the reanalysis model data, and the numerical wave model Delft-3D is used for estimating the nearshore wave parameters. The relative contribution of wind-seas and swells on LST rates are specifically examined. The clear prevalence of west-southwest waves implies the prevalence of south to north longshore sediment transport with net transport varying from 0.19–0.37 × 105 m3/yr. LST is strongly dependent on the breaker angle and a small change in the wave direction substantially alters the LST, and hence reanalysis/model data with coarse resolutions produce large errors (~38%) in the LST estimate. The annual gross LST rate based on integral wave parameters is only 58% considering the wind-seas and swells separately, since the wind-sea energy is comparable to swell energy, and the direction of these two systems differs significantly.

scholarly journals AN INTRODUCTION TO EVENT-BASED MODEL FOR THE STUDY OF SEDIMENT TRANSPORT IN THE SWASH ZONE

2011 ◽  
Vol 1 (32) ◽  
pp. 30
Author(s):  
Ahmad Shanehsazzadeh ◽  
Patrick Holmes
Keyword(s):  
Sediment Transport ◽  
Laboratory Data ◽  
Direct Result ◽  
Small Scale ◽  
Bed Load ◽  
Swash Zone ◽  
Beach Profile ◽  
Sediment Particles ◽  
Mode Of Transport ◽  
Event Based

Erosion and accretion of the beach face and consequently the movement of the coastline are the direct result of net sediment transport in the swash zone. Different models have been introduced in order to predict hydrodynamic parameters and, thereafter, movement of particles. However, the capability and comprehensiveness of the models in different conditions are still questionable. In reviewing models established for sediment transport in the swash zone, one can easily conclude that in the most cases the transport of bed load has been predicted traditionally by the application of quasi-steady formula. Scientists have identified many of the important physical processes driving sediment transport throughout the swash zone, but a detailed description of the small-scale sediment dynamics is still far from complete. In this paper the behaviour of coarse sediment particles in the bed load mode of transport in response to the flow regime experienced in the swash zone are investigated. Accordingly, a model called event-based model is introduced for prediction of the beach profile change, and the results of the model are compared with some laboratory data. The comparison between the results of the model and measured beach profile in the laboratory reveals that the results of the model developed in the present study on the basis of the event-based concept are very promising, particularly in the range of flow for which the behaviour of sediment particles is more accurately understood.

Longshore sediment transport and foreshore change in the swash zone of an estuarine beach

2017 ◽  
Vol 386 ◽  
pp. 88-97 ◽  
Author(s):  
Nancy L. Jackson ◽  
Karl F. Nordstrom ◽  
Eugene J. Farrell
Keyword(s):  
Sediment Transport ◽  
Swash Zone ◽  
Longshore Sediment Transport

Longshore sediment transport via littoral drift rose

2010 ◽  
Vol 37 (2-3) ◽  
pp. 228-235 ◽  
Author(s):  
Todd L. Walton ◽  
Robert G. Dean
Keyword(s):  
Sediment Transport ◽  
Littoral Drift ◽  
Longshore Sediment Transport

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 STRAND—A Model for Longshore Sediment Transport in the Swash Zone

2001 ◽  
Author(s):  
Erik Van Wellen ◽  
Tom Baldock ◽  
Andrew Chadwick ◽  
David Simmonds
Keyword(s):  
Sediment Transport ◽  
Swash Zone ◽  
Longshore Sediment Transport

Sediment transport and shoreline shifts in response to climate change at the tidal inlets of Chilika, India

2018 ◽  
Vol 233 (1) ◽  
pp. 372-387 ◽  
Author(s):  
B Gopikrishna ◽  
MC Deo
Keyword(s):  
Climate Change ◽  
Sediment Transport ◽  
Climate Model ◽  
Regional Climate ◽  
Shoreline Change ◽  
Tidal Inlets ◽  
Littoral Drift ◽  
The Past ◽  
Longshore Sediment Transport ◽  
Other Information

The shoreline adjoining Chilika Lake, situated along India’s east coast, has multiple tidal inlets which connect the lake with Bay of Bengal. The shoreline behavior near such inlets is generally studied with the help of a suitable numerical model. Such models are run on the basis of historical data of waves and other information. However, the waves in future may show different strength and pattern than the past as a result of the climate change induced by global warming. It is thus necessary that the model input should correspond to future or projected data of wind and waves. In this work, we have used the wind information from a state-of-the-art regional climate model, CORDEX RegCM-4, of future 25 years in order to run a shoreline evolution model and have derived the longshore sediment transport rate as well as the shoreline change rate around Chilika inlets. These future values are compared with corresponding ones of the past 25 years. It is found that at the given location, mean wind might go up by 20%, and this could raise the mean significant wave height strongly by 32%. The direction and frequency of occurrence of waves would also change, and this in turn will cause an increase in the net littoral drift by 41% and net accumulated drift over the entire cross-shore width by 84%. Interestingly, the present site where accretion was prevalent in the past may see erosion in future at the rate of about 1 m per year.

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.

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