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 EXPERIMENTAL INVESTIGATION ON DYNAMIC EQUILIBRIUM BAY SHAPE

2012 ◽  
Vol 1 (33) ◽  
pp. 37
Author(s):  
Sutat Weesakul ◽  
Somruthai Tasaduak
Keyword(s):  
Experimental Investigation ◽  
Sediment Transport ◽  
Dynamic Equilibrium ◽  
Shoreline Change ◽  
Sediment Supply ◽  
Coastal Protection ◽  
Supply Source ◽  
Wave Condition ◽  
Longshore Sediment Transport

Equilibrium bay is a bay that its shoreline is stable and does not change with time in long term. This concept can be applied for coastal protection. Experiments on dynamic equilibrium bay planform are conducted in a laboratory. There is one location of sediment supply source into a bay near upcoast headland and its magnitude vary from case to case. Wave obliquity varies from small to moderate values. These are two main parameters while wave condition is kept constant. The final bay planforms are investigated and recorded once they reach equilibrium with condition that sediment transport gradient approaches zero and no further shoreline change are observed. The parabolic equation similar to that for static equilibrium is newly proposed. The coefficients are originally derived and found to be a function of wave obliquity and the ratio of sediment supplied into bay to longshore sediment transport. The new dynamic equilibrium bay equation can be used and applied to study morphology change with variation of supplied sediment from inland.

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 Deficit of sand in a sediment transport model favors coral reef development in Brazil

2008 ◽  
Vol 80 (1) ◽  
pp. 205-214 ◽  
Author(s):  
Abílio C.S.P. Bittencourt ◽  
Zelinda M.A.N. Leão ◽  
Ruy K.P. Kikuchi ◽  
José M.L. Dominguez
Keyword(s):  
Sediment Transport ◽  
Transport Model ◽  
Order Approximation ◽  
Regional Scale ◽  
Coastal System ◽  
Wave Refraction ◽  
First Order ◽  
Sediment Transport Model ◽  
Longshore Sediment Transport ◽  
First Order Approximation

This paper shows that the location of the shoreface bank reefs along the northeastern and eastern coasts of Brazil, in a first order approximation, seem to be controlled by the deficit of sediment in the coastal system. The sediment transport pattern defined by a numerical modeling of wave refraction diagrams, representing circa 2000 km of the northeastern and eastern coasts of Brazil, permitted the regional-scale reproduction of several drift cells of net longshore sediment transport. Those drift cells can reasonably explain the coastal sections that present sediment surplus or sediment deficit, which correspond, respectively, to regions where there is deposition and erosion or little/no deposition of sand. The sediment deficit allows the exposure and maintenance of rocky substrates to be free of sediment, a favorable condition for the fixation and development of coral larvae.

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 Artificial Nourishments Effects on Longshore Sediments Transport

2021 ◽  
Vol 9 (3) ◽  
pp. 240
Author(s):  
Ana Margarida Ferreira ◽  
Carlos Coelho
Keyword(s):  
Sediment Transport ◽  
Numerical Models ◽  
Morphological Evolution ◽  
Temporal Distribution ◽  
Intervention Site ◽  
Coastal System ◽  
Longshore Sediment Transport ◽  
Longshore Transport ◽  
Erosion Mitigation ◽  
Artificial Nourishment

Serious erosion problems related to significant negative sediments budgets in the coastal systems are referred worldwide. Artificial nourishments are a coastal erosion mitigation strategy that allow for a decrease in those negative budgets by adding sediment to the coastal system. Thus, it is essential to understand and adequately model the shoreline response after a nourishment operation, in order to support the definition of the best intervention scenarios. The main goal of this work was to study the artificial nourishment effects on the longshore sediment transport and consequently on the morphological evolution at the intervention site and nearby areas, in a time horizon of 5 years. The longshore transport of the nourished sediments was evaluated, aiming to contribute to the evaluation of the sediment’s permanence at the deposition site and the frequency required for new nourishments. The shoreline evolution numerical long-term configuration (LTC) model was applied in order to evaluate the spatial and temporal distribution of the nourished sediments along the coast, considering different types of beaches and incident wave climates. The adopted approach is generic and supported by simple numerical models, which can be useful for preliminary site-specific evaluations. The results show that the nourishment impact is mainly observed nearby the intervention site. It is highlighted that higher longshore sediment transport rates are associated with more energetic wave climates, but not necessarily with incident waves more oblique to the shoreline.

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

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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