scholarly journals NUMERICAL MODELLING OF THE MORPHODYNAMICS OF THE PLOČE GRAVEL BEACH IN RIJEKA

2021 ◽  
Vol 12 (23) ◽  
pp. 33-48
Author(s):  
Goran Lončar ◽  
◽  
Filip Kalinić ◽  
Dalibor Carević ◽  
Damjan Bujak ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Numerical Model ◽  
Morphological Changes ◽  
Wind Waves ◽  
Surface Wind ◽  
Point Clouds ◽  
Beach Sediment ◽  
Model Simulations ◽  
Volume Method ◽  
Gravel Beach

The morphodynamics of an artificial gravel beach in the Bay of Rijeka (Ploče Beach) was analyzed. The morphological changes of the beach face were monitored through an intense situation of gravitational surface wind waves from the incident SSW direction. A numerical modeling technique was applied, after initially establishing a numerical model for wave deformation. A model for sediment transport was established based on its results. Both models were based on the finite volume method. In addition, the partial contribution of the longshore component of sediment transport was analyzed based on empirical formulae. The modeling results were verified by comparing the positions and amounts of eroded/accumulated material along the beach with the processing of terrain images in the form of point clouds. The erosion and accumulation positions of the beach sediment material, obtained by numerical model simulations, corresponded to the surveyed positions. The total volume of eroded and accumulated material based on terrain image processing corresponded to the model values.

scholarly journals APPLICATION OF XBEACH TO MODEL STORM RESPONSE ON A MACROTIDAL GRAVEL BARRIER

2011 ◽  
Vol 1 (32) ◽  
pp. 39 ◽  
Author(s):  
Amaia Ruiz de Alegria-Arzaburu ◽  
Jon J Williams ◽  
Gerhard Masselink
Keyword(s):  
Sediment Transport ◽  
Hydraulic Conductivity ◽  
Numerical Model ◽  
Morphological Changes ◽  
Coastal Engineering ◽  
Beach Profile ◽  
Morphological Response ◽  
Total Drag ◽  
Storm Response ◽  
Gravel Beach

The process-based XBeach numerical model has been used to simulate storm-induced morphological response on a macrotidal gravel barrier located in southwest UK. Using well-established parameterisation to define all relevant hydrodynamic, groundwater and sediment processes, the model was applied in 1D mode to simulate observed storm-induced beach profile responses. Investigations showed that the morphological response of the beach was best modelled using a total drag coefficient, CD, of 0.007, and a hydraulic conductivity, K, of 0.05ms-1. Results obtained from simulations with and without beach groundwater highlighted the need to account for groundwater effects when modelling morphological changes on gravel beaches. The model has been found unable of reproducing the formation of a berm, thus, beach recovery conditions cannot be modelled. This is mainly attributed to the fact that XBeach models long waves rather than individual waves, and thus it cannot simulate individual swash events that contribute to onshore sediment transport and berm accretion. However, the model is shown to provide good estimates of post-storm gravel beach/barrier profiles, and to define the threshold for overwash occurrence. Both attributes have utility in a range of practical coastal engineering and management applications.

Sediment transport modelling of the Drava River confluence

2020 ◽  
Author(s):  
Antonija Cikojević ◽  
Gordon Gilja ◽  
Sándor Baranya ◽  
Neven Kuspilić ◽  
Flóra Pomázi
Keyword(s):  
Sediment Transport ◽  
Numerical Model ◽  
Morphological Changes ◽  
River Mouth ◽  
Transport Modelling ◽  
River Confluence ◽  
Drava River ◽  
Sediment Transport Modelling ◽  
Transport Method

<p>Drava River confluence is characterized by specific morphodynamic processes under which significant sediment deposition is occurring at the Drava River mouth, impeding fairway conditions. Morphodynamic analysis requires long-term hydraulic and sediment transport regime data as input for estimation of equilibrium conditions, taking into account baseline conditions of both rivers. This paper presents results of detail investigations of morphodynamic changes at the Drava River confluence during the 2-year period. Quantification of morphodynamic processes is conducted indirectly through interpretation of ADCP transects surveyed over wider confluence zone, estimation of sediment transport intensity and bathymetric surveys. Purpose of the conducted analysis was to estimate morphodynamic development of the riverbed based on the 1D numerical model results. Numerical model is calibrated using flow velocity field and sediment transport pattern for range of hydrological events. Validation of sediment transport method is done through comparison of morphological changes on characteristic profiles between two consecutive surveys.</p>

scholarly journals A Numerical Model on Sediment Transport and Topographic Change of Sand and Gravel Beach

2013 ◽  
Vol 69 (2) ◽  
pp. I_626-I_630
Author(s):  
Kohji UNO ◽  
Hiroaki NAKANISHI ◽  
Gozo TSUJIMOTO ◽  
Tetsuya KAKINOKI
Keyword(s):  
Sediment Transport ◽  
Numerical Model ◽  
Sand And Gravel ◽  
Gravel Beach

scholarly journals Interactions Study of Hydrodynamic-Morphology-Vegetation for Dam-Break Flows

2016 ◽  
Vol 2016 ◽  
pp. 1-12
Author(s):  
Mingliang Zhang ◽  
Yuanyuan Xu ◽  
Jin Li ◽  
Huiting Qiao ◽  
Hongxing Zhang
Keyword(s):  
Numerical Model ◽  
Morphological Changes ◽  
Flow Region ◽  
Dam Break ◽  
Plant Distribution ◽  
Computational Domain ◽  
Dam Break Flow ◽  
Volume Method ◽  
Two Sides ◽  
Morphology Characteristics

This study models a dam-break flow over a bed by using a depth-averaged numerical model based on finite-volume method and computes the dam-break flow and bed morphology characteristics. The generalized shallow water equations considering the sediment transport and bed change on dam-break flow are adopted in the numerical model, and the vegetation effects on the flow and morphological changes are considered. The model is verified against three cases from the laboratory and field data documented in the literature. The numerical results are consistent with the measured results, which show that the model could accurately simulate the evolution of the dam-break flows and the morphology evolution of bed within a computational domain with complex plant distribution. The results show that the riparian vegetation in the waterway narrows the channel and reduces the conveyance capacity of river. The flood flow is diverted away from the vegetation community toward two sides and forms a weak flow region behind the vegetation domain. The resistance of plants markedly reduces the flow velocity, which directly alters the fluvial processes and influences the waterway morphology.

scholarly journals GRAVEL BEACH PROFILE EVOLUTION IN WAVE AND TIDAL ENVIRONMENTS

2012 ◽  
Vol 1 (33) ◽  
pp. 15
Author(s):  
Mohamad Hidayat Jamal ◽  
David J. Simmonds ◽  
Vanesa Magar
Keyword(s):  
Numerical Model ◽  
Water Level ◽  
Large Scale ◽  
Water Levels ◽  
Coarse Grained ◽  
Beach Profile ◽  
Model Simulations ◽  
Parameter Values ◽  
Future Work ◽  
Gravel Beach

This paper reports progress made in modifying and applying the X-Beach code to predict and explain the observed behaviour of coarse grained beaches. In a previous study a comparison of beach profile evolution measured during large scale experiments under constant water level with numerical model simulations was made. This placed particular emphasis on the tendency for onshore transport and profile steepening during calm conditions (Jamal et al., 2010). The present paper extends that investigation to study the influence of the advection of surf processes induced by tidal water level variations effects, on gravel beach profile evolution. The parameter values and numerical model used in the simulation is similar to that presented previously. It is assumed that, to good approximation, the groundwater interface inside the beach follows the tidally modulated water level. The results obtained from the model shows that the model provides reasonable simulations of beach profile change in a tidal environment. In comparison with simulations under stationary water levels, a larger berm is produced in agreement with literature. Finally, good agreement is obtained between the model simulations and an example of field observations from a beach at Milford on Sea, UK. Further developments are outlined for future work.

scholarly journals Morphodynamic Evolution of a Nourished Beach with Artificial Sandbars: Field Observations and Numerical Modeling

2021 ◽  
Vol 9 (3) ◽  
pp. 245
Author(s):  
Cuiping Kuang ◽  
Xuejian Han ◽  
Jiabo Zhang ◽  
Qingping Zou ◽  
Boling Dong
Keyword(s):  
Sediment Transport ◽  
Tidal Current ◽  
Model Simulation ◽  
Morphological Changes ◽  
Current Model ◽  
Beach Nourishment ◽  
Tidal Range ◽  
Coastal Protection ◽  
Field Observations ◽  
One Year

Beach nourishment, a common practice to replenish an eroded beach face with filling sand, has become increasingly popular as an environmentally friendly soft engineering measure to tackle coastal erosion. In this study, three 200 m long offshore submerged sandbars were placed about 200 m from the shore in August 2017 for both coastal protection and beach nourishment at Shanhai Pass, Bohai Sea, northeastern China. A series of 21 beach profiles were collected from August 2017 to July 2018 to monitor the morphological changes of the nourished beach. Field observations of wave and tide levels were conducted for one year and tidal current for 25 h, respectively. To investigate the spatial-temporal responses of hydrodynamics, sediment transport, and morphology to the presence of three artificial submerged sandbars, a two-dimensional depth-averaged (2DH) multi-fraction sediment transport and morphological model were coupled with wave and current model and implemented over a spatially varying nested grid. The model results compare well with the field observations of hydrodynamics and morphological changes. The tidal range was around 1.0 m and the waves predominately came from the south-south-east (SSE) direction in the study area. The observed and predicted beach profiles indicate that the sandbars moved onshore and the morphology experienced drastic changes immediately after the introduction of sandbars and reached an equilibrium state in about one year. The morphological change was mainly driven by waves. Under the influences of the prevailing waves and the longshore drift toward the northeast, the coastline on the leeside of the sandbars advanced seaward by 35 m maximally while the rest adjacent coastline retreated severely by 44 m maximally within August 2017–July 2018. The model results demonstrate that the three sandbars have little effect on the tidal current but attenuate the incoming wave significantly. As a result, the medium-coarse sand of sandbars is transported onshore and the background silt is mainly transported offshore and partly in the longshore direction toward the northeast. The 2- and 5-year model simulation results further indicate that shoreline salient may form behind the sandbars and protrude offshore enough to reach the sandbars, similar to the tombolo behind the breakwater.

scholarly journals A Hydrodynamic-Based Robust Numerical Model for Debris Hazard and Risk Assessment

2021 ◽  
Vol 13 (14) ◽  
pp. 7955
Author(s):  
Yongde Kang ◽  
Jingming Hou ◽  
Yu Tong ◽  
Baoshan Shi
Keyword(s):  
Numerical Model ◽  
Debris Flow ◽  
Finite Volume ◽  
Graphics Processing Unit ◽  
Morphological Changes ◽  
Finite Volume Scheme ◽  
Processing Unit ◽  
Algebraic Equations ◽  
Flow Process ◽  
Computing Technique

Debris flow simulations are important in practical engineering. In this study, a graphics processing unit (GPU)-based numerical model that couples hydrodynamic and morphological processes was developed to simulate debris flow, transport, and morphological changes. To accurately predict the debris flow sediment transport and sediment scouring processes, a GPU-based parallel computing technique was used to accelerate the calculation. This model was created in the framework of a Godunov-type finite volume scheme and discretized into algebraic equations by the finite volume method. The mass and momentum fluxes were computed using the Harten, Lax, and van Leer Contact (HLLC) approximate Riemann solver, and the friction source terms were calculated using the proposed splitting point-implicit method. These values were evaluated using a novel 2D edge-based MUSCL scheme. The code was programmed using C++ and CUDA, which can run on GPUs to substantially accelerate the computation. After verification, the model was applied to the simulation of the debris flow process of an idealized example. The results of the new scheme better reflect the characteristics of the discontinuity of its movement and the actual law of the evolution of erosion and deposition over time. The research results provide guidance and a reference for the in-depth study of debris flow processes and disaster prevention and mitigation.

Modelling river bank erosion using a 2D depth-averaged numerical model of flow and non-cohesive, non-uniform sediment transport

2016 ◽  
Vol 93 ◽  
pp. 75-88 ◽  
Author(s):  
Kamal El Kadi Abderrezzak ◽  
Andrés Die Moran ◽  
Pablo Tassi ◽  
Riadh Ata ◽  
Jean-Michel Hervouet
Keyword(s):  
Sediment Transport ◽  
Numerical Model ◽  
Bank Erosion ◽  
River Bank ◽  
River Bank Erosion
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