• Journal of The Geomorphological Association of Korea
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• v.25 no.2
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• pp.15-29
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• 2018

The sediment transport process in a river reflects the process of geomorphological change in the watershed, influencesthe river bed variation and the river channel migration, and is a parametric phenomenon that exhibits a dynamic self-adjusting process. Sediment load is divided into bedload and suspended load depending on the dominant mechanism. Quantitative sediment load is important information for solving river problems. Because it is difficult and time consuming to measure bedload, compared to that ofsuspended load, data on the sediment transport load and the research required for the gravel-bed rivers are insufficient. This study is to analyze the ratio of the bedload to the total sediment load in gravel-bed rivers. The sediment load ratio in gravel-bed rivers increases with the flow rate per unit width, and the rate of the bedload varies more rapidly than the suspended load. The sediment transport efficiency coefficient has been affected by the ratio of the flow depth to the mean diameter of particles and has been dependent on the shear velocity Reynolds number. So $A^{\ast}$ and $B^{\ast}$ are introduced to compensate for the uncertainties such as bed materials, sediment transport, and flow velocity distribution, and the coefficient of bedload ratio has been presented. For the sediment load data in experimental channels and rivers, A* was 3.1. The dominant variables of $B^{\ast}$ were $u_*d_m/{\nu}$ in the gravel-bed and h/dm in the sand-bed. When $B^{\ast}$ the is the same, in the experimental channels the coefficient of bedload ratio was affected by the bed forms, but in the rivers it was of little difference between the gravel-bed and sand-bed.

• Korean Journal of Environmental Agriculture
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• v.30 no.3
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• pp.268-274
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• 2011

BACKGROUND: A large scale of sediment load delivered from watershed causes substantial waterway damages and water quality degradation. Controlling sediment loading requires the knowledge of the soil erosion and sedimentation. The various factors such as watershed size, slope, climate, land use may affect sediment delivery processes. Traditionally sediment delivery ratio prediction equations have been developed by relating watershed characteristics to measured sediment yield divided by predicted gross erosion. However, sediment prediction equations have been developed for only a few regions because of limited sediment data. Besides, little research has been done on the prediction of sediment delivery ratio for asia monsoon period in mountainous watershed. METHODS AND RESULTS: In this study Tank model was expanded and applied for estimating sediment yield to Oship River of east coast. The rainfall-runoff in 2006 was verified using the Tank model and we derived good result between observed and calculated discharge in 2009 at the same conditions. In relation to sediment yield, the sediment delivery rate of 2006 was very high than 2009 regardless of methods for estimating sediment load. It was thought to be affected by heavy rainfall due to the typhoon. CONCLUSION(s): For estimating sediment volume from watershed, long-term monitoring data on discharge and sediment is needed. This model will be able to apply to predict discharge and sediment yield simultaneously in ungauged area. This approach is more effective and less expensive method than the traditional method which needs a lot of data collection.

• Journal of Korea Water Resources Association
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• v.51 no.2
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• pp.175-182
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• 2018

Coastal sediment archives are used as indicators of changes on shore sediment production and fluvial sediment transport, but rivers crossing coastal plains may not be efficient conveyors of sediment to the coast. In some case there is a net loss of sediment in lower coastal plain reaches, so that sediment input from an upstream exceeds the sediment yield (SY) at the river mouth. The main source of sediment in coastal area is the load from land. In Korea, data on suspended SY are limited owing to a lack of logistic support for systematic sediment sampling activities. This paper presents an integrated approach to estimate SY for ungauged coastal basins, using a soil erosion model and a sediment delivery ratio (SDR) model. For applying the SDR model, a basin specific parameter was validated on the basis of field data. The proposed relationships may be considered useful for predicting suspended SY in ungauged basins that have geologic, climatic and hydrologic conditions similar to the study area.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.4
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• pp.99-109
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• 1997

To estimate the nutrients delivery characteristics of Chogang stream to Keum River, sediment and soil characteristics were analyzed in the stream and in the stream bank. Along the stream, soil samples from river sediment were collected and tested monthly for phosphorus and nitrogen concentrations. Nitrogen concentration in the sediment is much lower than that of soil in the river bank especially in summer presumably due to the high desorption characteristics of nitrogen by the increasing rainfall energy during summer. Instead, the concentrations of phosphorus were similar for the sediment and the soil in the river bank due to the strong adsorption characteristics of phosphorus. Batch tests were performed to evaluate the desorption potential of the sediments. Universal Soil Loss Equation (USLE) was applied to quantify soil erosion in each watershed due to rainfall. It was estimated that approximately 25% of total phosphorus by mass basis could be released from the sediment if the water was disturbed vigorously. The mass load of nitrogen and phosphorus into the Chogang Stream from the watershed were evaluated from the USLE and release ratio of phosphorus.

• 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.

• Journal of Wetlands Research
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• v.9 no.3
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• pp.43-49
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• 2007

A ditch is a facility for managing washed-off runoff from parking lot area. Washed-off runoff inflows into ditches where it is retained for a short period of time. At this point, it is assumed that a ditch is a preliminary unit for runoff treatment. This research carries out the distribution of particle size and chemical compound for sediment in parking lot ditch. This work is important to understand the amount of generated sediment from this area to be able to determine different particle size ranges for treatment. Metal concentrations for sediment according to particle size are analyzed. From the distribution of particle size, the weight ratio with the range of $425-850{\mu}m$ is the highest. Considering its weight ratio, the metal concentration of coarser particles is high, otherwise metal concentration increases as particle size decreases. Metal load of the range is higher and the ratio of total metal load in the case of Cu, Pb, Zn is nearly 30%. Moreover metal concentration associated with particle size depends on particle ratio. To manage non-point source pollution for parking lot area, these results can be used with this ditch unit.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.5
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• pp.930-934
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• 2006

In this study, we conducted water-quality analysis of wastewater and in-situ flow measurement using automatic flow rate measuring instrument to identify characteristics of wastewater in urban areas, and collected samples in gutter fur storm water drain, rainfall bucket, and aqueduct of pipe from roof, and outfalls of basins to examine the contribution by pollution origins such as base wastewater, atmospheric washing, runoff by roof surface, runoff by road surface, erosion of sewer sediment. In the result, the concentration of pollutants reached peak in the beginning of rainfall due to first flush, was 3 to 10 times higher than average concentration of dry period, and was lower than that of dry period due to dilution of storm water. In the analysis of the contribution by pollution origins, the ratio of load by sewer sediment resuspension to the total pollution load was 54.6% fer COD, and 73.3% fur SS. Accordingly, we can reduce the total pollutant load by periodical dredging and washing of sewer sediment, and control the loadings by overflow of combined sewer overflows.

• Journal of Soil and Groundwater Environment
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• v.25 no.3
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• pp.52-64
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• 2020

The universal soil loss equation (USLE), a model for estimating the potential soil loss, has been used not only in research areas but also in establishing national policies in South Korea. Despite its wide applicability, USLE cannot adequately address the effect of seasonal variances. To overcome this limit, the ArcGIS-based Sediment Assessment Tool for Effective Erosion (ArcSATEEC) has been developed as an alternative model. Although the field-scale (< 100 ㎡) application of this model produced reliable estimation results, it is still challenging to validate accuracy of the model estimation because it only estimates potential soil losses, not the actual sediment yield. Therefore, in this study, a method for estimating actual soil loss based on the ArcSATEEC model was suggested. The model was applied to eight watersheds in South Korea to estimate sediment yields. Correction factor was introduced for each watershed, and the estimated sediment yield was compared with that of the estimated yield by LOAD ESTimator (LOADEST). Sediment yield estimation for all watersheds exhibited reliable results, and the validity of the proposed correction factor was confirmed, suggesting the correction factor needs to be considered in estimating actual soil loss.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.6
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• pp.699-709
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• 2017

We measured the grain size, total organic carbon (TOC), total nitrogen (TN), and heavy metals (As, Cd, Cr, Cu, Fe, Hg, Mn, Pb, and Zn) in order to understand the spatial distribution and pollution level of organic matter and metals in surface sediment around Goseong Bay, a shellfish farming area, Korea. The surface sediments were composed of finer sediments such as mud and clay. The concentration of TOC, TN, and heavy metals were much higher in the innermost bay than in the mouth and outside of bay. The spatial distribution of organic matter and heavy metals and C/N ratio (5-10) in sediment showed that the organic matter and heavy metals in sediment of the study region were significantly influenced by oceanic origin organic matter and anthropogenic sources, respectively. Based on the results of four assessment techniques (sediment quality guideline, geoaccumulation index, pollution load index, ecological risk index), the sediments around the Goseong Bay were a little polluted for heavy metals and the high metal concentrations in the northern region of bay could adverse impact on benthic organisms in sediment. Thus, the systematic management plan for the improvement of water and sediment environment and the concentrated monitoring of pollutants for sustainable aquaculture and seafood safety around Goseong Bay are necessary in the future.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.4
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• pp.392-402
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• 2020

We investigated the concentrations of acid volatile sulfide (AVS), ignition loss (IL), total organic carbon (TOC), total nitrogen (TN), and metallic elements (As, Cd, Cr, Cu, Fe, Hg, Mn, Pb, and Zn), in August 2015, to determine the spatial distribution and pollution status of organic matter and metals in the surface sediment of Jinju Bay, a spraying shellfish farming area, Korea. The concentrations of organic matter and metallic elements were significantly higher in the southern part of the bay than in the mouth and center of the bay. The C/N ratio (5.7~8.0) in the sediment represents the dominance of organic matter of oceanic origin in the surface sediment of the study area. The concentrations of AVS, TOC, and metals (As, Cd, Cr, Cu, Hg, Pb, and Zn) were much lower than the values of the sediment quality guidelines applied in Korea. Based on the results of the pollution load index (PLI) and ecological risk index (ERI), the metal concentrations in the surface sediment of Jinju Bay have a weakly negative ecological effect on benthic organisms although the sediments with high metal pollution status are distributed in the southern parts of the bay, with high dense shellfish farming areas. Thus, the surface sediments in Jinju Bay are not polluted with organic matter and are slightly polluted with metallic elements.