• Water Engineering Research
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• v.6 no.1
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• pp.17-30
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• 2005

The bed evolution of the stretch of the River Rhine between km-812.5 and km-821.5 is characterised by general bed degradation as a result of the river training works and dredging activities of the last two centuries. The degradation of the river bed affects the water levels, and so the navigation conditions. To combat the erosion of the river bed with the aim to keep up the shipping traffic and to avoid the ecological system damages due to water level reductions, sand-gravel-mixtures were added to the river (so called artificial grain feeding activities). This paper presents the results of an application of a graded sediment transport model in order to study morpholodynamical characteristics due to artificial grain feeding activities in the river stretch. The finite element code TELEMAC2D was used for flow calculation by solving the 2D shallow water equation on non-structured grids. The sediment transport module SISYPHE has been developed for graded sediment transport using a multiple layer model. The needs to apply such graded sediment transport approaches to study morphological processes in the domain are discussed. The calculations have been carried out for the case of middle water flow and different size-fraction distributions. The results show that the grain feeding process could be well simulated by the model.

• Journal of Wetlands Research
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• v.5 no.1
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• pp.53-66
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• 2003

The subject of sediment transport has been studied for centuries by engineers and river morpohologists. Many of the complex aspects of sediment transport are yet to be understood, and remain among the challenging subject for future studies. In this study, the finite element model is applied to various hypothetical channels. On the basis of the flow analysis results, sediment transport analysis is conducted using 3-different optional equations, and the results are compared with experimental results. For the purpose of predicting the sediment movements in natural river, RMA model is applied to Geum-River. It turned out to be very effective tool to predict various aspects of river evolution and the effects of hydraulic structures. The simulation results are also linked to the Geographic Information Systems (GIS).

• Proceedings of the Korea Water Resources Association Conference
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• 2002.05a
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• pp.3-16
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• 2002

This article describes some of the recent and on-going research developments of the author at Colorado State University. Advances in the field of sedimentation and river mechanics include basic research and computer modeling on several topics. Only a few selected topics are considered here: (1) analytical determination of velocity profiles, shear stress and sediment concentration profiles in smooth open channels; (2) experiments on bedload particle velocity in smooth and rough channels; (3) field measurements of sediment transport by size fractions in curved flumes. In terms of computer modeling, significant advances have been achieved in: (1) flashflood simulation with raster-based GIOS and radar precipitation data; and (2) physically-based computer modeling of sediment transport at the watershed scale with CASC2D-SED. Field applications, measurements and analysis of hydraulic geometry and sediment transport has been applied to: (1) gravel-bed transport measurements in a cobble-bed stream at Little Granite Creek, Wyoming; (2) sand and gravel transport by size fraction in the sharp meander bends of Fall River, Colorado; (3) changes in sand dune geometry and resistance to flow during major floods of the Rhine River in the Netherlands; (4) changes in hydraulic geometry of the Rio Grande downstream of Cochiti Dam, New Mexico; and (5) analysis of the influence of water temperature and the Coriolis force on flow velocity and sediment transport of the Lower Mississippi River in Louisiana. Recent developments also include two textbooks on "Erosion and Sedimentation" and "River Mechanics" by the author and state-of-the-art papers in the ASCE Journal of Hydraulic Engineering.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.62-66
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• 2010

This study presents velocities of bedload sediment transport in both longitudinal and lateral directions and applied in considering morphological change of straight open channel. The velocities of particle motion have obtained by considering the forces balance acting on particles on the bed between the drag, tangential component of the immersed weight of the particle, and Coulomb's resistive forces. Numerical profiles of particle motion velocities reveals good agreement in comparison between this study and Kovacs and Parker (1994). The evaluated velocities components of particle transport are get used to estimate bedload transport rate in considering morphological change of straight open channel. For the application, numerical solution is applied to laboratory experiment which shows very close solution profiles between this study and observed data of a self-formed straight channel.

• 한국해양학회지
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• v.22 no.1
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• pp.25-33
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• 1987

The transport and fate of fine-grained, cohesive sediments in an estuary were investigated numerically. A numerical model of sediment entrainment, deposition, and transport has been developed by incorporating recent results of laboratory and field investigations. The time-dependent flow fields produced by fiver inflow and semi-diurnal tides, were calculated, and the corresponding distributions of suspended-sediment concentrations were obtained. The time-changes of sediment bed condition due to entrainment and deposition were obtained. The entrained sediments contribute initially to high sediment concentrations in the estuary basin. As the time passes, the suspended-sediment concentrations were much reduced by the seaward transport due to residual currents. The erosional and dipositional areas were appeared to be strongly dependent on the current-velocity fields and sediment properties of the estuary.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.6
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• pp.511-516
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• 2004

As a preliminary study on the sediment flux, concentrations of suspended particulate matter and current speeds were measured at three inlets of Gwangyang Bay during one tidal cycle of a spring tide of March 2003. The suspended sediment flux rate $(g/m^{2}/s)$ at the mouth of Seomjin River (St. K1) was observed to be higher throughout surface layer during ebb tide $(14.3\;g/m^{2}/s)$ and throughout near-bottom layer during the flood tide $(23.2\;g/m^{2}/s),$ resulting in a net upstream-ward transport of$0.9{\times}10^{3}kg/m$ during 13 period. At the inlet toward Yeosu Bay (St. K2), a relatively low rate ($(5.0-6.7\;g/m^{2}/s)$ of sediment flux occurred throughout the water column compared to St. K1, with a depth-integrated net transport of $5.6{\times}10^{3}kg/m$ toward the outer reaches of Gwangyang Bay inlet. At St. K3 located at Gwangyang Bay-side of Noryang Strait, the outward flux toward the Jinju Bay was observed to be dominant during the flood tide $(16.2-23.2\;g/m^{2}/s)$, especially through the mid and near bottom layer, compared to the inward flux throughout the whole water column during the ebb tide $(13.1-19.7\;g/m^{2}/s).$ The net transport at St. K3 was calculated to be $4.0{\times}10^{3}kg/m$ toward the outside of Gwangyang Bay. The outward net transport of suspended sediment at all three inlets seems to be consistent with a trend of bottom sediment texture, which suggests a net movement of sediment from a relatively coarse and poorly sorted inner-bay toward a relatively fine and better sorted outer-bay environment.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.6
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• pp.547-556
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• 2007

The sediment transport by waves, wave-induced current and tidal current was calculated using the TRANSPOR2004, then the seasonal sediment budget was analyzed. Also, annual sediment budget was calculated, and sediment circulation patterns was deduced in the broad area including Haeundae beach. A sediment mainly inflows from the east coast of the beach and then moves to the eastward to the Dongback Is, where the 80% of inflow sediment transported to the eastward as a longshore sediment while 20% of them going out to the offshore at the center of the beach. Above results shows a good agreement with the sediment transport trend analysis results by the Gao model.

• Journal of the Korean GEO-environmental Society
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• v.15 no.4
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• pp.13-27
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• 2014

Catchments soil erosion, one of the most serious problems in the mountainous environment of the world, consists of a complex phenomenon involving the detachment of individual soil particles from the soil mass and their transport, storage and overland flow of rainfall, and infiltration. Sediment size distribution during erosion processes appear to depend on many factors such as rainfall characteristics, vegetation cover, hydraulic flow, soil properties and slope. This study involved laboratory flume experiments carried out under simulated rainfall in a 3.0 m long ${\times}$ 0.8 m wide ${\times}$ 0.7 m deep flume, set at $17^{\circ}$ slope. Five experimental cases, consisting of twelve experiments using three different sediments with two different rainfall conditions, are reported. The experiments consisted of detailed observations of particle size distribution of the out-flow sediment. Sediment water mixture out-flow hydrograph and sediment mass out-flow rate over time, moisture profiles at different points within the soil domain, and seepage outflow were also reported. Moisture profiles, seepage outflow, and movement of overland flow were clearly found to be controlled by water retention function and hydraulic function of the soil. The difference of grain size distribution of original soil bed and the out-flow sediment was found to be insignificant in the cases of uniform sediment used experiments. However, in the cases of non-uniform sediment used experiments the outflow sediment was found to be coarser than the original soil domain. The results indicated that the sediment transport mechanism is the combination of particle segregation, suspension/saltation and rolling along the travel distance.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.6
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• pp.405-411
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• 2013

A sediment transport calculation considering cohesive force is proposed to deal with the transport phenomena of cohesive sediment. In the proposed calculation, each sand particle is assumed to be surrounded by a thin layer of mud. The critical Shields parameter and bed-load sediment transport rate are modified to include the cohesive force acting on the sand particle. The proposed calculation is incorporated into a two-way coupled fluid-structure-sediment interaction model, and applied to wave-induced topographic change of artificial shallows. Numerical results show that an increase in the content ratio of the mud, cohesive resistance force per unit surface area and water content cause increases in the critical Shields parameter and decreases in the bed-load sediment transport rate, reducing the topographic change of the shallow without changing its trend. This suggests that mixing mud in the pores of the sand particles can reduce the topographic change of shallows.

• Water Engineering Research
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• v.3 no.2
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• pp.75-84
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• 2002

An Euler-Lagrange two-phase flow model is presented fur simulation sheet-flow transport under wave and current. The flow is computed by solving the Reynolds Averaged Navier-Stokes equation in conjunction with the k-$\varepsilon$ turbulence model for turbulence closure. The sediment transport is introduced as a motion of granular media under the action of unsteady flow from the Lagragian point of view. In other word, motion of every single particle is numerically traced with Movable Bed Simulator (MBS) code based on the Distinct Element Method (DEM), in which the frequent interparticle collision of the moving particles during the sheet-flow transport is sophisticatedly taken into account. The particle diameter effect on time-dependent developing process of sheet-flow transport is investigated, by using three different diameter sizes of sediment. The influence of an imposed current on oscillatory sheet-flow transport is also investigated. It is concluded that the sediment transport rate increases due to the relaxation process related to the time-lag between flow velocity and sediment motion.