Sediment Transport Studies Research Articles

Analysis of diversion ratio and study of sediment transport in the first canal station of an irrigation area based on Mike21 hydrodynamic model

Abstract Based on MIKE21 hydrodynamic model, the change of diversion ratio and sediment transport at the first canal station in an irrigation area are analyzed. Two-dimensional numerical simulation is carried out by using MIKE21 FM hydrodynamic module, and the split ratio is studied. In the aspect of sediment transport, the transport path and deposition distribution of different sediment particle sizes are simulated by simulating sediment transport. The results show that under the lowest daily average water level, the diversion canal flow can meet the irrigation demand; The particle size of sediment has a great influence on the deposition distribution and thickness of the approach channel at the first station of the canal, and then affects the water diversion capacity of the pumping station.

A 45-Year Updating Wind and Wave Hindcast Over the Oman Sea and the Arabian Sea

This study focuses on developing a comprehensive and reliable wind and wave hindcast for the Oman Sea and Arabian Sea, spanning a significant 45-year period (1979-2024). The objective is to capture the intricate wind and wave climate of the region, characterized by distinct monsoon cycles and occasional tropical cyclones. The availability of extensive wave data over four decades would be an irreplaceable tool for researchers and engineers, enabling improved accuracy in extreme value analysis, sediment transport studies, and wave-induced current simulations. Despite limited field observations, all available measured data within the region were collected, analyzed for configuration of the models and utilized for model calibration and validation. The hindcast data was generated using the Weather Research and Forecasting (WRF) model for winds and WAVEWATCH III (WW3) model for waves, and evaluated against observational and measured wind and wave parameters. A comprehensive statistical analysis of the hindcast model's performance reveals adequate agreement with measured data, as evidenced by root mean square errors (RMSEs) of 1.23m/s for wind speeds and 0.37m for significant wave heights in average. These results underscore the model's reliability for research and engineering applications, particularly in the Arabian Sea, with a focus on the northern coastlines of the Oman Sea. The specific model configuration employed in this study holds significant potential for future investigations in the northern Indian Ocean, offering a valuable tool for understanding and predicting climatical conditions in this region.

A numerical model for calculating velocity distribution in cross-section of an open channel

Flow velocity in open channels is a fundamental hydraulic parameter with wide-ranging applications, including the development of rating curves and the study of sediment transport. While some river engineering projects may only require the calculation of average flow velocity, others, such as the design of hydraulic structures and stable channels, as well as the assessment of boundary shear stress, necessitate a more comprehensive understanding of flow dynamics, including the two-dimensional velocity distribution within open channels. To address this, various mathematical models have been proposed for estimating the two-dimensional distribution of flow velocity across transverse and depth directions. However, these models often come with complexities that hinder their practical application. In this research, we introduce a simplified numerical model that combines simplified Navier–Stokes equations with an eddy viscosity formula. This innovative approach aims to estimate velocity distribution in both rectangular and trapezoidal channels. The accuracy of our developed model hinges on the momentum transfer coefficient used in the eddy viscosity formula. Through the execution of the numerical model and the utilization of observational data, we determined the optimal value of the momentum transfer coefficient to be 0.241. To validate the effectiveness of our numerical model, we compared its predictions with laboratory data encompassing diverse hydraulic conditions. The results demonstrated a high level of accuracy, with the calculated velocity distribution and flow discharge differing by no more than 7.6% and 6.8%, respectively.

A semi-implicit finite volume method for the Exner model of sediment transport

The aim of this work is to construct efficient finite volume schemes for the numerical study of sediment transport in shallow water, in the framework of the Exner model [7,10]. In most cases, the velocity related to the sediment is much lower that the fluid velocity, which, in turn, may be much lower that the free-surface wave speed. Explicit methods that resolve all waves require small time steps due to the CFL stability restriction because of fast surface waves. Furthermore, if Rusanov flux is adopted, slow sediment waves may be affected by the large numerical diffusion. The objective of the present work is to drastically improve the efficiency in the computation of the evolution of the sediment by treating water waves implicitly, thus allowing much larger time steps than the one required by fully explicit schemes. The goal is reached by suitably semi-implicit schemes obtained by the use of implicit-explicit Runge-Kutta methods.

Aeolian Sediment Transport Responses to Vegetation Cover Change: Effects of Sampling Error on Model Uncertainty

AbstractAlthough it is widely known that observations of aeolian sediment transport are susceptible to large sampling errors, sample designs are frequently used that do not sufficiently reduce the measurement uncertainties inherent in the study of aeolian processes. Here, we examine the influence of sample size (n) and sampling location on uncertainty in models of aeolian sediment transport responses to vegetation cover change. We compare measurements from a stratified random array of 27 horizontal sediment mass flux samplers to vegetative cover data collected at a 1 ha site over a period of nearly 6 years. To assess the sensitivity of modeled relationships between aeolian transport and vegetative cover to sample design, we analyze statistical regressions for all possible combinations of sample size and sampler locations. We show that at least 17 randomly located samplers are needed to consistently capture the sediment mass flux response to vegetative cover change. We found that multiple statistically significant models can describe the sediment flux‐vegetative cover relationship when using smaller sample sizes, demonstrating the risks of inferring sediment transport response from an underpowered sample design. Across vegetative functional groups, we found that woody cover generally influenced aeolian sediment transport rates more than herbaceous cover, while model uncertainty at large sample sizes (n > 17) showed the limitation of using vegetative cover as an indicator of aeolian sediment transport. Our results suggest an evaluation of sampling practices in aeolian sediment transport studies may be needed to avoid inferential errors that are likely pervasive in this field of study.

DEPTH-RESOLVED MODELLING OF SEDIMENT FLUXES UNDER BICHROMATIC WAVES IN THE SWASH ZONE

Traditionally, many numerical studies of sediment transport or morphodynamics in the swash zone use depth-averaged approach. This is relatively computationally cheap, however, the assumptions it makes on vertical structures of the flow velocity and suspended sediment concentration are not always fully met. Depth-resolving models, albeit more computationally expensive, offer the ability to investigate sediment transport without imposing assumptions on vertical structures. Therefore, these models are a great tool for investigating processes related to sediment transport in the swash zone. In this study, will look at the behavior of suspended sediment in the swash zone, and the role vertical structures therein.

Suspended sediment deposition and sediment yields at Lake Peters, northeast Brooks Range, Alaska: Fluvial‐ and lake‐based approaches

AbstractLake‐based studies can provide seasonal‐ to millennial‐scale records of sediment yield to improve our understanding of catchment‐scale sediment transfer and complement shorter fluvial‐based sediment transport studies. In this study, sediment accumulation rates at 40 coring locations in Lake Peters, Brooks Range, Alaska, over ca. 42 years, calculated using fallout radionuclides and sediment density patterns, were spatially modelled based on distance from the primary inflow and lake water depth. We estimated mean interdecadal specific sediment yield (Mg km−2 year−1) using the spatially modelled sediment accumulation rates and compared that result to fluvial‐based sediment delivery for 2015–2016 open‐channel seasons, as well as to yields reported for other Arctic catchments. Using the lake‐based method, mean yield to Lake Peters between ca. 1973 and 2015 was 52 ± 12 Mg km−2 year−1, which is comparable with fluvial‐based modelling results of 33 (20–60) Mg km−2 year−1 in 2015 and 79 (50–140) Mg km−2 year−1 in 2016 (95% confidence intervals), respectively. Although 2016 was a year of above average sedimentation, the last extreme depositional event probably occurred between ca. 1970 and 1976 when a basal layer of fine sand was deposited in a broadly distributed, relatively thick and coarse bed, which we used for lake‐wide correlation. The dual lacustrine–fluvial method approach permits study of within‐lake and catchment‐scale processes. Within Lake Peters, sedimentation patterns show decreasing fluxes down‐lake, sediment bypassing near the primary inflow, the influence of secondary inflows and littoral redistribution, and a focusing effect in the deep proximal basin. At the watershed scale, sediment yield is largely driven by intense summer rainfall and strong seasonal hydroclimatic variability. This research informs paleo‐environmental reconstruction and environmental system modelling in Arctic lake catchments.

Scaling laws for planetary sediment transport from DEM-RANS numerical simulations

We use an established discrete element method (DEM) Reynolds-averaged Navier–Stokes (RANS)-based numerical model to simulate non-suspended sediment transport across conditions encompassing almost seven orders of magnitude in the particle–fluid density ratio$s$, ranging from subaqueous transport ($s=2.65$) to aeolian transport in the highly rarefied atmosphere of Pluto ($s=10^7$), whereas previous DEM-based sediment transport studies did not exceed terrestrial aeolian conditions ($s\approx 2000$). Guided by these simulations and by experiments, we semi-empirically derive simple scaling laws for the cessation threshold and rate of equilibrium aeolian transport, both exhibiting a rather unusual$s^{1/3}$-dependence. They constitute a simple means to make predictions of aeolian processes across a large range of planetary conditions. The derivation consists of a first-principle-based proof of the statement that, under relatively mild assumptions, the cessation threshold physics is controlled by only one dimensionless control parameter, rather than two expected from dimensional analysis. Crucially, unlike existing models, this proof does not resort to coarse-graining the particle phase of the aeolian transport layer above the bed surface. From the pool of existing models, only that by Pähtzet al.(J. Geophys. Res.: Earth, vol. 126, 2021, e2020JF005859) is somewhat consistent with the combined numerical and experimental data. It captures the scaling of the cessation threshold and the$s^{1/3}$-dependence of the transport rate, but fails to capture the latter's superimposed grain size dependence. This hints at a lack of understanding of the transport rate physics and calls for future studies on this issue.

Field investigation of suspended sediment transport study in the Kandla creek, Gujarat, India

ABSTRACT The formation of shoals, leading to a reduction in the required depth for navigation, is a perennial problem in approach channels of harbours and estuaries. Likewise, this is a major obstacle to the navigation of larger vessels to the study area reported in this paper . A field study on Kandla creek estuary was conducted to assess the flow and sediment dynamics inside the creek where one of the major ports of India, Deendayal Port, is located. In-situ water and sediment sampling and discharge measurements were carried out for the pre-monsoon, end of the monsoon and post-monsoon seasons in 2019–2020. Further, the grain size analysis and total suspended sediment analysis were done from the collected samples. The results highlight the domination of strong ebb currents in pre-monsoon and flood currents at the end of the monsoon and post-monsoon in the creek, which influences the sediment transport proportionately. The present paper reports the sediment characteristics and the estimated net sediment transport through measurements along with flow characteristics in Kandla creek. The field data presented here will support the researchers in the numerical modeling and validation of hydrodynamics and morphodynamics in the estuaries.

Comparative Study of Sediment Transport using the Caldwell and Cerc Methods at the Donggala Fish Landing Base

Donggala Fish Landing Port (PPI) is a fish port located in Central Sulawesi, precisely in Labuan Bajo Village, Banawa District, Donggala Regency, which is located along the high seas coast. The change in shoreline at the Donggala Fish Landing Base is caused by sediment transport that occurs due to wind and incoming waves. This study aims to determine the sediment characteristics, the amount of longshore sediment transport that occurs per year, and the ratio of the amount of sediment transport for 10 years using the Caldwell method and the CERC method. Analysis of sediment characteristics was carried out by testing carried out in the laboratory with the analyzed parameters, namely: sediment density, sediment grain size distribution and sedimentation velocity. There are many methods that can be used to calculate sediment transport, including the Caldwell method and the CERC method. The results of the sedimentation analysis, it is found that the sediment fraction is sand with various diameters, namely ϕmin = 0.075 mm and ϕmax = 25 mm, sediment density γmin = 2,604 g/cm3 and γmax = 2,678 g/cm3 and sedimentation velocity Wmin = 0.251 m/s and Wmax = 9,946 m/s. From the calculation of sediment transport analysis using the Caldwell method, the maximum amount of sediment transport that occurred in 2009 was 0,956 m3/year and for the CERC method, the maximum amount of sediment transport occurred in 2009 was 0,210 m3/year. The calculation of sediment transport analysis that was reviewed for 10 years, the value obtained by the Caldwell method Qs = 3,353 m3/year, while the CERC method Qs = 0,705 m3/year so that the amount of sediment transport using the Caldwell method is greater than using the CERC method.

Experimental study and numerical simulation of fluvial dynamics and sediment transport in instationary flow conditions

Experimental study and numerical simulation of fluvial dynamics and sediment transport in instationary flow conditions

Hydrodynamic and Sediment Transport Studies of Gorgan Bay (Case Study: Khozeini Channel and Investigation of Jetty’s Role in Reducing Active Sedimentation After Channel Dredging)

Hydrodynamic and Sediment Transport Studies of Gorgan Bay (Case Study: Khozeini Channel and Investigation of Jetty’s Role in Reducing Active Sedimentation After Channel Dredging)

Contrasting modes of sediment infilling and geomorphic change within a sand dominated dredge pit on the inner Louisiana shelf

While many sediment transport studies have been performed on mud capped dredge pits (MCDP), there is a paucity of sediment infilling data for sand dominated dredge pits (SDDP) in the Northern Gulf of Mexico (NGoM). In this study, bathymetry, sidescan, and subbottom data were collected in 2018, 2019, and 2020 and sediment cores were collected between the 2019 and 2020 surveys at Block 88: a dredge pit sitting on the sand-dominated Ship Shoal of Louisiana's inner shelf. The crest of Ship Shoal was 5 m below mean sea level before dredging and was excavated to a depth of 10 m below mean sea level after the dredging of 8.4 million m3 of sediment. Two years after dredging, the northern end of the eastern pit wall accumulated ∼0.09 million tons (approximately 500 m long × 50 m wide × 2.5 m deep) of sediment, driven by westward longshore sediment transport and the deposition of bed load on the shoal crest. Sediment accumulation on the pit bottom was mainly driven by suspended load at a rate of ∼0.1 m yr−1 from 2018 to 2019 and ∼0.2 m yr−1 from 2019 to 2020. Thus, the sediment infilling in Block 88 was from both bed- and suspended-loads from contrasting sources. These pit-bottom sediment accumulation rates are approximately one order of magnitude lower than the predicted rate from a previous empirical modeling study conducted on Ship Shoal and lower than the rates (0.5–2 m yr−1) of three other MCDPs on the inner Louisiana shelf. The infilling sediment was patchy and predominantly silt and clay, with lower sidescan reflectivity. The slopes of Block 88's pit walls decreased from ∼20° in 2018 to ∼8° in 2020. These values were smaller than the values of pit wall slopes in MCDPs at a similar stage (i.e., 2–3 years after dredging). Our results indicate that the highest sediment accumulation rates occur immediately adjacent to the eastern pit wall of Block 88, which is down-current of the longshore transport direction. This study helps sand resource managers and policymakers to better plan and design future sediment dredging projects on sandy shoals. This study concludes that the longest axis of a dredge pit should be aligned perpendicular to the longshore transport direction to trap the most sediments for possible reuse. Additionally, both bed load and suspended load should be considered in future modeling to better predict sediment infilling.

Sediment sources and delivery of Norwegian mountain rivers in a changing climate

AbstractThe projected climate change for Norway through the 21st century predicts that the temperature will increase significantly. Events with heavy rainfall will be more intense and occur more frequently. Rain floods will increase in magnitude and also occur more frequently. Extreme flooding and heavy rain will significantly impact the sediment dynamics in rivers. In the mountain areas, floods are often associated with erosion, transport and deposition of coarse sediment along the streams. These processes are related to bed load transport and pose a hazard in addition to the elevated water discharge and have to be included in management plans for river basins. This article studies the bed load delivery from sources that contribute the most to the sediment budget in the Gudbrandsdalslågen river basin during the large magnitude floods in 2011 and 2013. More than 100 debris slides and debris flow were triggered in the tributary river Veikleåi by the heavy rain and snowmelt during these floods. The volume of the contribution from debris flows and erosion and deposition of the river bed was determined by subtracting digital elevation models acquired during repeated airborne LIDAR surveys. In the river Dørja the supply of sediment from a number of debris flows caused extensive aggradation and channel changes. In their new position, lateral erosion by these channels triggered slides on the adjacent slopes. The contributing volumes of debris flows, lateral erosion, and river bed erosion and deposition were determined from the LIDAR surveys. Relations obtained from studies of sediment transport in modern glacier rivers were used to obtain estimates of the ratio of bed load versus suspended load derived from the Pleistocene moraine deposits. Several monitoring stations using conventional methods for measuring bed load and suspended load recorded very large volumes of sediment delivery during both of the extreme floods. The results of the study may be used to identify necessary locations for check‐dams and erosion protection works in order to adapt to climate change.

Inclusive Hyper- to Dilute-Concentrated Suspended Sediment Transport Study Using Modified Rouse Model: Parametrized Power-Linear Coupled Approach Using Machine Learning

The transfer of suspended sediment can range widely from being diluted to being hyper-concentrated, depending on the local flow and ground conditions. Using the Rouse model and the Kundu and Ghoshal (2017) model, it is possible to look at the sediment distribution for a range of hyper-concentrated and diluted flows. According to the Kundu and Ghoshal model, the sediment flow follows a linear profile for the hyper-concentrated flow regime and a power law applies for the dilute concentrated flow regime. This paper describes these models and how the Kundu and Ghoshal parameters (linear-law coefficients and power-law coefficients) are dependent on sediment flow parameters using machine-learning techniques. The machine-learning models used are XGboost Classifier, Linear Regressor (Ridge), Linear Regressor (Bayesian), K Nearest Neighbours, Decision Tree Regressor, and Support Vector Machines (Regressor). The models were implemented on Google Colab and the models have been applied to determine the relationship between every Kundu and Ghoshal parameter with each sediment flow parameter (mean concentration, Rouse number, and size parameter) for both a linear profile and a power-law profile. The models correctly calculated the suspended sediment profile for a range of flow conditions (0.268 mm≤d50≤2.29 mm, 0.00105gmm3≤particle density≤2.65gmm3, 0.197mms≤vs≤96mms, 7.16mms≤u*≤63.3mms, 0.00042≤cˉ≤0.54), including a range of Rouse numbers (0.0076≤P≤23.5). The models showed particularly good accuracy for testing at low and extremely high concentrations for type I to III profiles.

Living on the edge: How traits of ecosystem engineers drive bio-physical interactions at coastal wetland edges

Salt marshes and mangrove forests provide critical ecosystem services such as reduced sediment erosion and increased hydrodynamic buffering. Sediment transport and hydrodynamics can be influenced by specific functional traits of the plants (for example, flexibility vs. rigidity) and community traits (for example, spatial density). While there is a growing body of literature on plant trait and hydrodynamic interactions, direct comparative studies of sediment transport and scour development in and around intertidal wetland edges are scarce. In this study we systematically compared the effects of plant traits on sediment budgets around the lateral edges of intertidal wetlands under controlled hydrodynamic and sedimentary conditions using full scale vegetation mimics with contrasting flexibilities and densities. Experiments were carried out in a large-scale flume, using two spatial densities each of flexible and rigid vegetation mimics. We measured unconsolidated sedimentary bed-level changes in experimental runs using waves only, currents only, and waves combined with currents. Both mimic types dampened the energy of the incoming flow, highlighting the role of rigid and flexible aquatic vegetation in providing coastal protection. The rigid vegetation mimics’ lateral edge experienced larger velocities, more energetic turbulence, and local scour around individual stems. Scour around stems could influence the lateral expansion of the rigid vegetation ecosystem by reducing sediment stability and thus decreasing seedling establishment success. The flexible plant mimics produced lower turbulence at their leading edge, which resulted in sediment being deposited over a shorter distance into the patch than in the rigid mimics. Decreased vegetation density caused reduced sediment erosion at the leading edge and less sediment accumulation within the vegetation patches for both the rigid and flexible mimics. The hydrodynamic and sedimentary processes identified for both ecosystems are linked to different feedbacks. A positive feedback was identified in which vegetation attenuates hydrodynamic energy allowing sediment accumulation within the patch. A negative feedback was identified where large velocities caused flow divergence and erosion outside of the vegetation, and would therefore compromise its lateral expansion. High densities of rigid vegetation enhance this negative feedback. Lower density flexible vegetation, however, combined with less energetic hydrodynamic conditions facilitate the expansion of vegetation patches as they cause less flow divergence and therefore less erosion. The strong flow divergence observed in the rigid vegetation cases highlight their importance for buffering hydrodynamics but at the cost of increased erosion within the front end of patches and along their lateral edges.

ASSESSMENT OF STEADY FLOW BEHAVIOUR OF KULSI RIVER USING HEC-RAS AND QGIS

Sediment transport study is important tools of Kulsi River in the context of river bank erosion, Sedimentation, and water quality management. The initiation of computer technologies has enabled engineers to resolve sediment transport equations through computer simulations. In this study, it is intended to carry out a sediment transport study in the Kulsi River reach with the help of Hydrologic Engineering Centre-River Analysis System (HEC-RAS) and Quantum Geographic information System (QGIS). From the analysis of the model, total sediment erosion and deposition were obtained at different cross sections between the study reach. Kulsi river is Southern tributary of Brahmaputra and it’s originate in Meghalaya (2538N, 9138E) and after travelling 12 km its enter Assam from the place of its origin and linked with Brahmaputra at Nagarbara in Kamrup Metro. The initial version of this sediment model will leverage the wide range of hydraulic capabilities existing in HEC-RAS to compute a series of steady flow profiles used to develop hydrodynamic parameters for sediment transport. In this model where sufficient data is not available, So QGIS and remote sensing used as tools for extraction of bed profile of Kulsi River. HEC-RAS and QGIS are the Software used in this study. This study is carried out to simulate the process of erosion and sedimentation using HEC- RAS model to assess sedimentation and erosion processes in 2.5 Km stretch of Kulsi River from upstream to downstream. The model was calibrated manually for hydraulic parameters of river flow and then sediment transport model was simulated from January 2016 to December 2016. Key Words: Steady flow, HEC-RAS 5.05, QGIS, TCX converter.

A Combined O/U-Tube Oscillatory Water Tunnel for Fluid Flow and Sediment Transport Studies: The Hydrodynamics and Genetic Algorithm

This study proposes an oscillatory water tunnel (O/U-tube) equipped with two impellers to drive flows. The O/U-tube consists of two modes: U-tube mode and O-tube mode. The former can generate oscillatory flow, while the latter can produce both oscillatory and unidirectional flows with velocities up to 1.6 m/s. The hydrodynamics of the U-tube and O-tube modes were examined analytically. For the U-tube mode, a sine-varying rotational speed for the impeller caused higher harmonic components for the velocity, owing to the local inertia and gravity forces. In the steady state of the O-tube mode, owing to the resistance force, the flow velocity was proportional to the rotational speed. To generate the target flow conditions, two open-loop control schemes were proposed according to the analytic approach for the U-tube mode and a genetic algorithm for the O-tube mode. The analytic approach was based on a hydrodynamic model with a given flow condition. In the genetic algorithm, the rotational speed was represented by a square root of the Fourier series. The optimal coefficients of the Fourier series to generate the target flow were determined by using the genetic algorithm and the hydrodynamic model. Both approaches were experimentally validated. Consequently, the O/U-tube with the open-loop schemes can be used to generate the desired oscillatory and unidirectional flows.

Simulation of Sediment Transport in River Ogunpa Using Winxpro Software

The numerical modelling of sediment transport of a river has long been developed. Rivers across Nigeria has interdicted researchers on modelling sediment transport. The environmental problem makes sediment transport study an important area among morphological mechanisms. This research studied the Simulation and modelling of sediment transport in River Ogunpa using WinXspro software. Suspended Sediment concentration was measured from November 2015 to June 2016 across the upstream, midstream and downstream of River Ogunpa using standard methods. The values of manning’s roughness factor used varied from 0.012 – 0.018. Sediment discharges (QS) were computed across the river using Acker and White approach. The average Suspended Sediment Concentration (SSC) across River Ogunpa varied from 2 – 64mg/L. The mathematical relationship for the sediment discharge value was QS = 64625Q + 12922. The estimated Qs varied from 0.00 – 23012kg/s. The variation in measured and validated discharge ranged between 0.95 – 4.19%. Sediment discharge across River Ogunpa was simulated using Winxpro software. The sediment discharge value can be a piece of useful information for dredging operation on River Ogunpa.

Numerical study of sediment transport in Thu-Bon estuary and coastal areas of Hoi-An City

The area of Cua-Dai estuary and the coastal areas of Hoi-An City have experienced complicated erosion and sedimentation in recent years. Along the coast of Hoi-An, erosion often occurs, whereas in the area of Cua-Dai River, there is an accretion phenomenon that obstructs the waterway navigation from Cua-Dai to Cu-Lao-Cham. Occurrence of sand dunes in the offshore location of Cua-Dai has been recorded at a number of times in recent years. Studying the process of bed morphological change due to the sediment transport in the Thu-Bon river and the influence of monsoons in the area allows to explain the above phenomenon thus an in-depth study to propose appropriate solutions. This study used the numerical model Telemac which combines the hydro-morphodynamic and wave modules. The simulation results show that the main trend of coastal currents caused by tides and waves tends to go southward, leading to coastal erosion especially in the northeast monsoon season as well as sedimentation in the estuarine area. In addition, the model also shows the crucial role of waves in shoreline erosion, with the degree of erosion in the north coast near Cua-Dai being more severe than the southern coast, through the formation of local eddy flow on the north coast.