Characterizing the Longshore Sediment Transport Pattern on Beaches in the Gulf of Arauco, Chile, to Assess Morphological Shoreline Evolution

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.

Simulations of Shoreline Changes along the Delaware Coast

10.21079/11681/39559 ◽

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 ◽

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.

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

Ovidius University Annals of Constanta - Series Civil Engineering ◽

10.2478/ouacsce-2019-0001 ◽

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 ◽

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.

Comparison of three longshore sediment transport rate formulae in shoreline evolution modeling near stream mouths

Ocean Engineering ◽

10.1016/j.oceaneng.2014.10.005 ◽

2014 ◽

Vol 92 ◽

pp. 255-266 ◽

Cited By ~ 6

Author(s):

Achilleas G. Samaras ◽

Christopher G. Koutitas

Keyword(s):

Sediment Transport ◽

Transport Rate ◽

Sediment Transport Rate ◽

Shoreline Evolution ◽

Evolution Modeling

CRITERION FOR STABILITY OF SHORELINE PLANFORM

10.9753/icce.v17.77 ◽

1980 ◽

Vol 1 (17) ◽

pp. 77

Author(s):

John D. Wang ◽

Bernard Le Mehaute

Keyword(s):

Sediment Transport ◽

Deep Water ◽

Water Wave ◽

Shoreline Evolution ◽

Longshore Transport ◽

Long Time ◽

Wave Angle ◽

Deep Water Wave ◽

Offshore Transport

The problem of beach planform stability has been known for a long time: When does a small perturbation on a straight beach tend to grow with time and when does it tend to be flattened out? The interest in this problem arises from evidence of instabilities occurring in nature, but perhaps more importantly it is a problem that must be taken into account when formulating models for beach evolution and erosion. Existing mathematical models describing shoreline changes assume that the beach planform is stable and in equilibrium. It is therefore important to establish the range of wave conditions for which instabilities could occur, thereby invalidating such models. In the present case our interest is specifically directed towards determining conditions for which a model for shoreline evolution is intangible because of development of local instability. Grijm (1960) gave an approximate mathematical analysis indicating that at the point where the longshore sediment transport Q as a function of wave angle is maximum the shoreline must either be straight or form a cusp. Under his assumption that Q is proportional to sin 2a the maximum occurs for a = 45°. Le Mehaute and Soldate (1977) summarizes other studies that essentially arrive at the same results, viz. when the deep water wave angle is greater than 45° the shoreline is unstable. This result did not seem to be substantiated by field or laboratory observations. In this study of shoreline planform we first derive a criterion for instability of straight beaches. Then assuming that longshore sediment transport is proportional to the alongshore wave energy flux component at the point of breaking we determine the range of deep water wave characteristics and beach slopes which would cause unstable situations to occur. We consider only the longshore transport and exclude effects of on-offshore transport.

PROBABILISTIC SHORELINE CHANGE MODELING AND RISK ESTIMATION OF EROSION

10.9753/icce.v36.papers.1 ◽

2018 ◽

pp. 1

Author(s):

Yan Ding ◽

Ashley E. Frey ◽

Sung-Chan Kim ◽

Rusty E. Permenter

Keyword(s):

Monte Carlo ◽

Sediment Transport ◽

Shoreline Change ◽

Likelihood Method ◽

Random Waves ◽

Shoreline Changes ◽

Model Based ◽

Shoreline Evolution ◽

Wave Heights

Prediction of long-term shoreline changes is a key task in planning and management of coastal zones and regional sediment management. Due to complex natural features of offshore waves, sediments, and longshore sediment transport, quantifying uncertainties of shoreline evolution and risks of extreme shoreline changes (erosion and accretion) is of vital importance for practicing uncertainty- or risk-based design of shorelines. This paper presents probabilistic shoreline change modeling to quantify uncertainties of shoreline variations by using numerical-model-based Monte-Carlo simulations. A shoreline evolution model, GenCade, is used to simulate longshore sediment transport and shoreline changes induced by random waves from offshore. A probability density function with a modified tail distribution is developed to capture stochastic features of wave heights under fair weather and storm conditions. It produces a time series of wave heights including small and extreme waves based on their probabilities (or frequencies of appearance). Probabilistic modeling of shoreline change is demonstrated by computing spatiotemporal variations of statistical parameters such as mean and variance of shoreline changes along an idealized coast bounded by two groins. Maximum shoreline changes in return years with a confidence range are also estimated by using maximum likelihood method. Reasonable results of obtained probabilistic shoreline changes reveal that this model-based Monte-Carlo simulation and uncertainty estimation approach are applicable to facilitate risk/uncertainty-based design and planning of shorelines.

MODELLING LONG-TERM SHORELINE EVOLUTION: FIGUEIRA DA FOZ BEACH, PORTUGAL

10.9753/icce.v35.sediment.17 ◽

2017 ◽

pp. 17

Author(s):

Carla Pereira ◽

Carlos Coelho ◽

Paulo A. Silva

Keyword(s):

Sediment Transport ◽

Numerical Models ◽

Shoreline Position ◽

Shoreline Evolution ◽

Time Period ◽

Accretion Rates ◽

Time Periods

This work applies two different shoreline evolution numerical models (LTC and GENESIS) in two different time periods (1980 2010 and 2010-2014) to compare respectively the calibration and validation performance of the models. The models were applied to evaluate long-term shoreline position and longshore sediments transport evolution, considering as a case study a sandy beach stretch located updrift of the Figueira da Foz harbor jetty, on the Northwest Portuguese coast. Due to the jetty extension, this stretch exhibits a clear accretion trend during the analyzed time periods. For this region, the longshore sediment transport rate estimated by several authors varies between 200 and 1500x103m3/year. According to the modelling results, it was observed that both models reproduce reasonably well the shoreline evolution between 1980 and 2010. In average, the LTC model reproduces a 2010 shoreline position nearest the observed and GENESIS presents better approximation in the Northern part of the beach and also near the South (downdrift) border (just close to the Northern jetty of the harbor). The modeled shoreline average accretion rates for the considered stretch is quite similar and close to the values referred in the bibliography, which indicates that the beach presents 500 meters of maximum accretion width updrift the jetty (about 16.6m/year). In what concerns to the longshore sediment transport it was observed that numerical models generally indicate lower values than the bibliography, being GENESIS results higher and closer to the observed than the LTC. These results are common in the numerical modelling of shoreline evolution, showing that is difficult to simultaneously represent both the shoreline position and sediment transport volumes. After calibration, LTC validation was evaluated for the time period between 2010 and 2014 to allow confidence in the extrapolation of results to the future. Estimated deposition rates of about 350x103m3/year were obtained at the harbor entrance.

IMPROVED LONGSHORE SAND TRANSPORT EVALUATION

10.9753/icce.v21.103 ◽

1988 ◽

Vol 1 (21) ◽

pp. 103

Author(s):

A.S. Arcilla ◽

A. Vidaor ◽

J. Pous

Keyword(s):

Sediment Transport ◽

Dimensional Analysis ◽

Surf Zone ◽

Dynamic State ◽

Sand Transport ◽

Hydrodynamic Analysis ◽

Shoreline Evolution ◽

Proposed Model ◽

The One

In this paper an improved bulk formulation for the longshore sediment transport rate is presented. It is based on a simplified hydrodynamic analysis of surf zone flow and supplemented by an exhaustive dimensional analysis. The proposed model includes the effect of the surf zone dynamic state (e.g. variation of longshore sand transport, II, with breaker type) and it is now being used in the one- and twoline shoreline evolution models developed by the Maritime Engineering Laboratory in Barcelona.