scholarly journals In Use of Permeable Groin for Reducing Longshore Sediment Transport at Tanjung Bayang Beach of South Sulawesi

2018 ◽  
Vol 1 (2) ◽  
pp. 70-73 ◽  
Author(s):  
Hasdinar Umar ◽  
Sabaruddin Rahman ◽  
Chairul Paotonan ◽  
Ahmad Yasir Baeda
Keyword(s):  
Sediment Transport ◽  
Coastal Protection ◽  
Breaking Wave ◽  
Longshore Current ◽  
Surrounding Area ◽  
South Sulawesi ◽  
Longshore Sediment Transport ◽  
Reduction Coefficient ◽  
Before And After ◽  
Transport Analysis

Breaking wave near beaches is the main force to generate longshore currents, which moved the sediment at surrounding area. Due to its negative outcome, which are erosion and sedimentation, the need of longshore sediment transport analysis become very important. One of the tools for solving that problem is by using coastal protection structure such as permeable groin. Permeable groin may reduce the rate of longshore sediment transport respectively by changing the level of permeability of the groin itself. The objective of this research was to obtain analytical results of the longshore sediment transport reduction analysis by using permeable groins at Tanjung Bayang Beach of South Sulawesi. Reduction of sediment transport along the beach was analyzed by calculating reduction coefficient, which is the ratio between the longshore current before and after hitting the permeable groins. The result showed that with 40% of permeability, the groin can reduced longshore sediment transport at Tanjung Bayang Beach for almost 50%; from 341.37x103 m3/year to 170.68x103 m3/year.

Prediction of Longshore Sediment Transport Using Soft Computing Techniques

2008 ◽  
Author(s):  
Roham Bakhtyar ◽  
David Andrew Barry ◽  
Abbas Ghaheri
Keyword(s):  
Sediment Transport ◽  
Fuzzy Inference System ◽  
Fuzzy Inference ◽  
Transport Rate ◽  
Breaking Wave ◽  
Input Output ◽  
Empirical Formulas ◽  
Inference System ◽  
Longshore Sediment Transport ◽  
Soft Computing Techniques

An important task for coastal engineers is to predict the sediment transport rates in coastal regions with correct estimation of this transport rate, it is possible to predict both natural morphological or beach morphology changes and the influence of coastal structures on the coast line. A large number of empirical formulas have been proposed for predicting the longshore sediment transport rate as a function of breaking wave characteristics and beach slope. The main shortcoming of these empirical formulas is that these formulas are not able to predict the field transport rate accurately. In this paper, an Adaptive-Network-Based Fuzzy Inference System which can serve as a basis for consulting a set of fuzzy IF-THEN rules with appropriate membership functions to generate the stipulated input-output pairs, is used to predict and model longshore sediment transport. For statistical comparison of predicted and observed sediment transport, bias, Root Mean Square Error, and scatter index are used. The results suggest that the ANFIS method is superior to empirical formulas in the modeling and forecasting of sediment transport. We conclude that the constructed models, through subtractive fuzzy clustering, can efficiently deal with complex input-output patterns. They can learn and build up a neuro-fuzzy inference system for prediction, while the forecasting results provide a useful guidance or reference for predicting longshore sediment transport.

scholarly journals SIMULATION OF LONG-TERM SHORELINE CHANGE DRIVEN BY LONGSHORE AND CROSS-SHORE SEDIMENT TRANSPORT

2020 ◽  
pp. 31
Author(s):  
Yan Ding ◽  
Sung-Chan Kim ◽  
Richard B. Styles ◽  
Rusty L. Permenter
Keyword(s):  
Sediment Transport ◽  
Shoreline Change ◽  
Breaking Wave ◽  
Beach Profile ◽  
Shoreline Evolution ◽  
Longshore Sediment Transport ◽  
Wave Energy Flux ◽  
Semi Empirical ◽  
Evolution Modeling

Driven by wave and current, sediment transport alongshore and cross-shore induces shoreline changes in coasts. Estimated by breaking wave energy flux, longshore sediment transport in littoral zone has been studied for decades. Cross-shore sediment transport can be significant in a gentle-slope beach and a barred coast due to bar migration. Short-term beach profile evolution (typically for a few days or weeks) has been successfully simulated by reconstructing nonlinear wave shape in nearshore zone (e.g. Hsu et al 2006, Fernandez-Mora et al. 2015). However, it is still lack of knowledge on the relationship between cross-shore sediment transport and long-term shoreline evolution. Based on the methodology of beach profile evolution modeling, a semi-empirical closure model is developed for estimating phase-average net cross-shore sediment transport rate induced by waves, currents, and gravity. This model has been implemented into GenCade, the USACE shoreline evolution model.

scholarly journals Simulations of Shoreline Changes along the Delaware Coast

2021 ◽  
Author(s):  
Yan Ding ◽  
Sung-Chan Kim ◽  
Rusty L. Permenter ◽  
Richard B. Styles ◽  
Jeffery A. Gebert
Keyword(s):  
Sediment Transport ◽  
Coastal Sediments ◽  
Coastal Protection ◽  
Shoreline Evolution ◽  
Longshore Sediment Transport ◽  
Technical Report ◽  
Indian River ◽  
Sediment Transfer ◽  
Island Coast

This technical report presents two applications of the GenCade model to simulate long-term shoreline evolution along the Delaware Coast driven by waves, inlet sediment transport, and longshore sediment transport. The simulations also include coastal protection practices such as periodic beach fills, post-storm nourishment, and sand bypassing. Two site-specific GenCade models were developed: one is for the coasts adjacent to the Indian River Inlet (IRI) and another is for Fenwick Island. In the first model, the sediment exchanges among the shoals and bars of the inlet were simulated by the Inlet Reservoir Model (IRM) in the GenCade. An inlet sediment transfer factor (γ) was derived from the IRM to quantify the capability of inlet sediment bypassing, measured by a rate of longshore sediments transferred across an inlet from the updrift side to the downdrift side. The second model for the Fenwick Island coast was validated by simulating an 11-y ear-long shoreline evolution driven by longshore sediment transport and periodic beach fills. Validation of the two models was achieved through evaluating statistical errors of simulations. The effects of the sand bypassing operation across the IRI and the beach fills in Fenwick Island were examined by comparing simulation results with and without those protection practices. Results of the study will benefit planning and management of coastal sediments at the sites.

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.

scholarly journals LONGSHORE SEDIMENT TRANSPORT RATE vs. CROSS - SHORE DISTRIBUTION OF SEDIMENT GRAIN SIZES

1988 ◽  
Vol 1 (21) ◽  
pp. 145
Author(s):  
C.I. Moutzouris
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Transport Rate ◽  
Longshore Current ◽  
Sediment Grain Size ◽  
Grain Sizes ◽  
Sediment Transport Rate ◽  
Power Equation ◽  
Longshore Sediment Transport ◽  
The Cross

Existing models for longshore sediment transport rate computations assume the sediment grain size and grain sizerelated parameters to be uniform in both the cross-shore and longshore directions. Field results from tideless beaches, which are briefly described in the paper, show that the latter change in both directions due to changing wave energylevels. The sensitivity analysis described in the paper shows that both longshore current and transport rate computations are sensitive to the cross-shore changes in grain size.Finally, a modified linearity coefficient for the wave power equation is proposed based upon the cross-shore distributions of grain size as found in nature.

scholarly journals DISTRIBUTION OF SAND TRANSPORT RATE ACROSS A SURF ZONE

1978 ◽  
Vol 1 (16) ◽  
pp. 95 ◽  
Author(s):  
Toru Swaragi ◽  
Ichiro Deguchi
Keyword(s):  
Shear Stress ◽  
Sediment Transport ◽  
Surf Zone ◽  
Transport Rate ◽  
Sand Transport ◽  
Shear Stresses ◽  
Bottom Shear Stress ◽  
Longshore Current ◽  
Unidirectional Flow ◽  
Longshore Sediment Transport

The distributions of longshore and on-offshore sediment transport rates in a surf zone were measured by an apparatus which was able to separately record both components of the sediment transport rate,, The characteristics of their distributions were discussed from the bottom shear stresses which were measured by the shear meter under the same wave conditions as the laboratory experiment of the sediment transport. The maximum bottom shear stress took place at the depth between the breaking depth of waves and the depth where the velocity of the longshore current showed a maximum. On the other hand, the maximum on-offshore and longshore sediment transport rates occured at the depth slightly shallower than the depth where the maximum bottom shear stress took place. What's more, the longshore sediment transport rates were represented by the longshore current velocity and the bottom shear stress generated by waves and the longshore current. However, the distribution of the on-offshore sediment transport rates showed more complicated profile than that of the longshore sediment transport rates because there were no eminent unidirectional flow in the direction normal to the shore line. Therefore, the on-offshore sediment transport rates could not be formulated by the bottom shear stresses.

scholarly journals LONGSHORE CURRENT AND TRANSPORT ACROSS NON-SINGULAR EQUILIBRIUM BEACH PROFILES

1988 ◽  
Vol 1 (21) ◽  
pp. 104
Author(s):  
Kevin R. Bodge
Keyword(s):  
Sediment Transport ◽  
Longshore Current ◽  
Beach Profile ◽  
Infinite Slope ◽  
Profile Shape ◽  
Equilibrium Beach Profile ◽  
Longshore Sediment Transport ◽  
Beach Processes ◽  
Mathematical Expressions ◽  
Equilibrium Profile

The longshore current and longshore sediment transport distributions are described across an equilibrium beach profile comprised of an intersecting planar foreshore and a concave-up profile. Such a profile shape avoids the singularity associated with the infinite-slope at the shoreline described by traditional equilibrium profile forms and allows prediction of beach processes at and above the shoreline. The mathematical expressions which describe the distributions are simplified and can be more readily applied relative to expressions previously presented in the literature. The findings are in general agreement with similar previous analytic studies and indicate that the current and transport maxima are generally located at about the intersection of the planar and concave-up portions of the profile.

scholarly journals LONGSHORE SEDIMENT TRANSPORT ON DEAN BEACH PROFILES

1984 ◽  
Vol 1 (19) ◽  
pp. 101
Author(s):  
William G. McDougal ◽  
Robert T. Hudspeth
Keyword(s):  
Sediment Transport ◽  
Eddy Viscosity ◽  
Viscosity Coefficient ◽  
Strength Parameter ◽  
Longshore Current ◽  
Transport Models ◽  
Longshore Sediment Transport ◽  
Equilibrium Profile ◽  
Eddy Viscosity Coefficient ◽  
Stress Models

Natural beaches exhibit an equilibrium profile that is planar nearshore and non-planar, concave-up offshore. The longshore current on these Dean equilibrium beaches is shown to depend on the location of the intersection between the planar and non-planar profiles and on the dimensionless mixing strength parameter if the eddy viscosity coefficient is linearly dependent on the distance offshore. The effect of the profile intersection on the longshore sediment transport rate is demonstrated for two energetics based sediment transport models; viz. the Bagnold and energetics stress models.

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