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 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 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 FIELD INVESTIGATION OF SEDIMENT TRANSPORT PATTERN IN A CLOSED SYSTEM

1976 ◽  
Vol 1 (15) ◽  
pp. 72
Author(s):  
Tsuguo Sunamura ◽  
Kiyoshi Horikawa
Keyword(s):  
Sediment Transport ◽  
Closed System ◽  
Shoreline Change ◽  
Field Investigation ◽  
Depositional Environments ◽  
Aerial Photographs ◽  
Beach Sand ◽  
Sieve Analysis ◽  
Alongshore Sediment Transport

In order to elucidate the transport pattern of sediment in a closed system, a pocket beach was chosen and investigated from various aspects. This investigation included the following studies: (1) bathymetric survey by an echo sounder, (2) survey of submarine geology using an acoustic probe, (3) observation of nearshore current systems using floats, (4) documentation of the transport pattern of suspended sediment by aerial photographs, (5) examination of depositional environments of bottom and beach material by sieve analysis, (6) inference of long-term alongshore sediment transport pattern from the grain size properties of beach sand, and measurement of short-term trends by use of fluorescent sand, and (7) examination of long-term shoreline change using old and recent maps.

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.

scholarly journals Coastal Processes and Longshore Sediment Transport along Zemmouri Bay, Central East Coast of Algeria

2019 ◽  
Vol 21 (1) ◽  
pp. 7-15
Author(s):  
Khoudir Mezouar ◽  
Romeo Ciortan
Keyword(s):  
Sediment Transport ◽  
Morphological Changes ◽  
Shoreline Change ◽  
Spatial And Temporal Scales ◽  
Wave Refraction ◽  
Shoreline Evolution ◽  
Longshore Sediment Transport ◽  
Western Area ◽  
Waves And Currents ◽  
Comprehensive Study

Abstract The coastline of Zemmouri Bay on the northeast coast of Algeria with about 50 km of shoreline has been eroding since 1970. Changes of the sandy shoreline are continuous and occur at diverse spatial and temporal scales. This erosion is a major crisis and it potentially impacts the coastal population and natural environment. In order to understand and predict these morphological changes, an accurate description of sediment transport by waves and currents and shoreline change is important. This paper presents a comprehensive study of wave refraction, current-driven sediment transport and shoreline change. Results show that the study area exhibits a great variety of shoreline evolution trends, with erosion prevailing in the eastern and central sectors and stability or even accretion in the Western area.

scholarly journals Investigating Changes in Aeolian Sediment Transport at Coastal Dunes and Sand Trapping Fences: A Field Study on the German Coast

2020 ◽  
Vol 8 (12) ◽  
pp. 1012
Author(s):  
Christiane Eichmanns ◽  
Holger Schüttrumpf
Keyword(s):  
Sediment Transport ◽  
Wind Profile ◽  
Field Experiments ◽  
Coastal Dunes ◽  
Sediment Supply ◽  
Sediment Flux ◽  
Coastal Protection ◽  
Protection Measures ◽  
Law Of The Wall ◽  
Aeolian Sediment

For the restoration and maintenance of beach and dune systems along the coast, knowledge of aeolian sediment transport and its interaction with coastal protection measures is required. As a nature-based solution, sand trapping fences can be an integral part of coastal protection measures initiating foredune development. There are few detailed studies on aeolian sediment transport rates on coastal dunes and sand trapping fences available to date. Thus, in this work, we present the results of field experiments conducted at the beach, coastal dune, and sand trapping fence on the East Frisian island Langeoog. The vertical sediment flux profile was measured by vertical mesh sand traps, and saltiphones measured the instantaneous sediment transport. A meteorological station was set up to obtain wind data. On the beach, dune toe, and dune crest, the stationary wind profile can be described well by the law of the wall. Saturated aeolian sediment transport rates on the beach and dune toe were predicted by widely used empirical models. Between the sand trapping fence, these empirical transport models could not be applied, as no logarithmic wind profile existed. The upwind sediment supply reduced after each brushwood line of the sand trapping fence, thereby, leading to increased deviation from the saturated conditions.

Sediment supply from shoreface to dunes: linking sediment transport measurements and long-term morphological evolution

Geomorphology ◽  
2004 ◽  
Vol 60 (1-2) ◽  
pp. 205-224 ◽  
Author(s):  
Troels Aagaard ◽  
Robin Davidson-Arnott ◽  
Brian Greenwood ◽  
Jørgen Nielsen
Keyword(s):  
Sediment Transport ◽  
Morphological Evolution ◽  
Sediment Supply ◽  
Transport Measurements

scholarly journals Decadal Shoreline Stability in Eastbourne,  Wellington Harbour

2021 ◽  
Author(s):  
◽  
David Olson
Keyword(s):  
Grain Size ◽  
Aerial Photograph ◽  
Sediment Supply ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Beach Morphology ◽  
Longshore Sediment Transport ◽  
Longshore Transport ◽  
Beach Width

<p>Mixed Sand and Gravel (MSG) Beach research in recent decades has overwhelmingly focussed on open-oceanic environments, however, those found in fetch limited settings remain poorly understood. This thesis has examined spatial and temporal morphological change through such a system in Eastbourne, Wellington Harbour, New Zealand. This site has only recently prograded following several decades of erosion. This accretion has been the result of a northward migrating gravel front, which is introducing gravel sized sediment into the previously sandy system resulting in significant changes in beach morphology and volume. The aim of this study is to quantify these spatial and temporal changes and to assess shoreline stability on a decadal timescale. Additionally it aims to ascertain whether the current progradation is a long term change to the system or the result of a short term sediment increase. This assessment has been conducted in the form of topographic surveying, grain size and aerial photograph analysis. The topographic surveying and grain size analysis provides an accurate description of beach morphology. This is compared to the established MSG beach morphology models for the open coast, but operating on a smaller scale because of the lower energy fetch-limited environment of the study area. Aerial photograph analysis is used to show the longer term changes in beach width and the northern migration of the gravel fraction of the sediment supply regime. The spatial analysis results show that the beach morphology is highly variable. In the embayments that are more exposed to oceanic swell waves beach profiles are broad and steep, and in the beaches in the northern sections of the coastline which are more sheltered from oceanic swell waves, profiles are flat and narrow. The temporal results show that the coastal accretion observed through the study area has been initially rapid, followed by sustained increased beach width. These results suggest that the morphological variation on this coastline is part of a long term adjustment to a change in sediment supply, initiated by tectonic uplift and subsequently driven by longshore sediment transport. The observed mechanism of longshore transport has been suggested to be a function of sediment properties, relative wave energy and bathymetry/topography. The findings of this research are used to develop a conceptual model of shoreline evolution for the study area in response to changes that have occurred over the last 154 years.</p>

scholarly journals Prediction of Shoreline Change for the Calculation of the Integrated Littoral Sediment Budget

Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 232
Author(s):  
Yeon-Joong Kim ◽  
Jong-Sung Yoon
Keyword(s):  
Sediment Transport ◽  
Coastal Erosion ◽  
Evaluation System ◽  
Shoreline Change ◽  
Sediment Budget ◽  
Prediction Performance ◽  
Sediment Supply ◽  
Sediment Runoff ◽  
Observation Data ◽  
Sediment Volume

The severe coastal erosions are being accelerated along the east coast of South Korea owing to the intermittent erosions and depositions caused by the imbalance between the effective sediment volume supplied from coasts and rivers and the sediment transport rate. Consequently, many studies are being conducted to develop coastal-erosion reduction measures. To accurately determine the cause of coastal erosion, the causes of the erosion and deposition should be accurately diagnosed, and a comprehensive evaluation system for the sediment transport mechanism in the watershed and sea while considering regional characteristics is required. In particular, realizing the evaluation of the effective sediment volume that flows from the river to the sea through observations is a highly challenging task, and various research and developments are required to realize it, as it is still in the basic research stage. The purpose of this study was to systematically analyze the comprehensive sediment budget for coastal areas. First, an analytical system was developed. Then, a shoreline model was constructed by considering the size of the mixed particles. The parameters required for developing the model were determined using the observation data to improve the shoreline model. A sediment runoff model was applied to evaluate the effective sediment volume supplied from the river to the sea, and the applicability of this model was evaluated by comparing it with the sediment supply volume according to the soil and water assessment tool model. The representative wave and the input parameters of the model were set using the observation data of several years. It was found that the prediction performance of the shoreline change model improved when the effective sediment volume was considered, and the particles of the sediment on the shore were assumed to comprise multiple sizes. In particular, the prediction performance improved when the balance of the sediment budget was adjusted by applying a groin having a structurally similar performance to take into consideration the geographic features of the Deokbongsan (island) in front of the river mouth bar. The model demonstrated a good performance in reproducing long-term shoreline changes when the characteristics of the sea waves and the effective sediment volume were considered.

Sign in / Sign up

Export Citation Format

Share Document