• Journal of Environmental Science International
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• v.2 no.2
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• pp.153-160
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• 1993

The problem of supply and transport of sediment from a mountainous catchment is very important in explaining dynamic geomorphology and the hydrological cycle. The discharge of suspended sediment is determined by a morphological system. Human interference to environment Is also an important, not negligible factor in sediment production. Moreover, growing concern in recent years for the problems of nonpoint pollution and for the transport of contaminants through terrestrial and aquatic ecosystems has highlighted the role of sediment-associated transport in fluvial systems. This study was conducted in forested and quarried catchments in order to clarify the different discharge process and the mechanism of suspended sediment dynamics for each catchment. As a forested catchment, the Yamaguchi River catchment which drains a $3.12km^2$ area was chosen. On the other hand, the Futagami River basin which is formed by three subbasins (1.07, 1.59 and $1.78km^2$), as a quarried catchment was selected. These catchments are situated to the north and east of Mt. Tsukuba, Ibaraki, Japan. The discharge pattern of suspended sediment from the Futagami River basin is more unstable and irregular than that from forested catchment, the Yamaguchi River catchment. Under the similar rainstorm conditions, suspended sediment concentration from quarried catchment during a rainstorm event increases from 43 to 27,340 mg/l. However, in the case of the forested catchment it changes only from nearly zero to 274 mg/l. Generally, the supply source of suspended sediment is classified into two areas, the in-channel and non-channel source areas. As a result of field measurements, in the case of the forested catchment the in-channel (channel bed, channel bank and channel margin) is the main source area of suspended sediment. On the other hand, remarkable sediment source area on the Quarried catchment is the non-channel that is unvegetated ground.

• Journal of The Korean Society of Agricultural Engineers
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• v.66 no.2
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• pp.53-62
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• 2024

This study assessed the efficiency of reducing soil erosion and suspended sediment through the restoration of alpine unauthorized and illegally cultivated fields, using the SWAT (Soil and Water Assessment Tool) model in the Mandae District. The results showed that in Scenario 5, which involved restoring unauthorized and illegal fields within forests, along rivers (banks), and in ditch areas were restored to their original land categories, achieved the highest efficiency in reducing average annual soil erosion and suspended sediment, with reductions of 8.1% and 4.5%, respectively. In particular, it was confirmed that the restoration of unauthorized and illegal fields within forested areas has a significant impact. This demonstrated that the restoration of unauthorized and illegal agricultural fields can substantially reduce the soil erosion and suspended sediment attributable to non-point source pollution. Our findings highlight the importance of managing these unauthorized and illegal agricultural activities in developing sustainable strategies within non-point source pollution management areas. This study is expected to provide important basic data to effectively establish water quality improvement strategies in the region of non-point source pollution management.

• Journal of Environmental Science International
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• v.12 no.3
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• pp.247-255
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• 2003

Forest management starts from forest road facility, which is designated as generation source of muddy water in mountain stream during initial stage of establishment. Therefore, this study reviewed the effect of suspended sediment generated in forest road surface on the muddy water in mountain stream with respect to marsh area of forest. As a result, characteristics of outflow of suspended sediment was understood, and it was judged that generation of suspended sediment due to establishment of forest road is diluted by mountain stream this charged from drainage area so as to have small effect on muddy water in total mountain stream.

• 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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3B
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• pp.311-319
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• 2006

A bed level change model(SED-FLUX) is introduced based on the realistic sediment transport process including bed load and suspended load behaviours at the bottom boundary layer. The model SED-FLUX includes wave module, hydrodynamic module and sediment transport and diffusion module that calculate suspended sediment concentration, net sediment erosion flux($Q_s$) and bed load flux. Bed load transport rate is evaluated by the van Rijn's TRANSPOR program which has been verified in wave-current fields. The net sediment erosion flux($Q_s$) at the bottom is evaluated as a source/sink term in the numerical sediment diffusion model where the suspended sediment concentration becomes a verification parameter of the $Q_s$. Bed level change module calculates a bed level change amount(${\Delta}h_{i,j}$) and updates a bed level. For the model verification the limit depth of the bed load transport is compared with the field experiment data and some formula on the threshold depth for the bed load movement by waves and currents. This model is applied to the beach profile changes by waves, then the model shows a clear erosion and accumulation profile according to the incident wave characteristics. Finally the beach evolution by waves and wave-induced currents behind the offshore breakwater is calculated, where the model shows a tombolo formation in the landward area of the breakwater.

• Environmental Engineering Research
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• v.17 no.3
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• pp.167-174
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• 2012

In situ particle size spectra are obtained from two sequent cruises in order to evaluate the physical consequences of suspended particulate matters caused by episodic storm runoff from the Santa Ana River watershed, an urbanized coastal watershed. Suspended particles from various sources including surface runoff, near-bed resuspension, and phytoplankton are identified in empirical orthogonal function (EOF) analysis and an entropy-based parameterization (Shannon entropy). The first EOF mode is associated with high turbidity and fine particles as indicated by the elevated beam attenuation near the Santa Ana River and Newport Bay outlets, and the second EOF mode explains the suspended sediment dispersal and particle coarsening at the near-surface plume. Chlorophyll particles are also distinguished by negative magnitudes of the first EOF mode, which is supported by the relationship between fluorescence and beam attenuation. The integrated observation between the first EOF mode and the Shannon entropy index accentuates the characteristics of two different structures and/or sources of sediment particles; the near-surface plumes are originated from runoff water outflow, while the near-bottom particles are resuspended due to increased wave heights or mobilizing bottom turbidity currents. In a coastal pollution context, these methods may offer useful means of characterizing particle-associated pollutants for purposes of source tracking and environmental interpretation.

• Journal of Wetlands Research
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• v.5 no.1
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• pp.67-78
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• 2003

The unsteady 2D convection and diffusion equation is solved numerically for the real-time simulation of suspended load propagation. The streamlined upwind scheme efficiently reduces numerical oscillations due to the high Peclet number in the convection dominant flow. By using the mixed boundary condition to express the external source terms or externally induced suspended load as a function of time in the algorithm, the model is capable of handling not only continuous load cases but also non-continuous suspended load influx. The suspended load transport modelwas verified using a case study for which an analytical exact solution is available and was applied to the real-time simulation of a suspended load influx case on the Mississippi River. The model algorithm can provide a framework upon which water quality as well as contaminant transport models can be built.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.133-136
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• 2004

In-situ collection experiments were performed to analyze inflowing sedilnents behavior as a basic study of topographical change in Nakdong River Estuary. Sediment rate and bed load flux ranged from 0.0004 to $0.472\;g/cm^2/day\;and\;0.0005\~1.7579\;g/cm^2/day$, respectively. The settling velocity of suspended particulate matter was estimated in tire range of $0.339\~1.010\;cm/sec$, The grain size analysis shows that surface sediments in backside of sandbar and bed load in front of dike have a similar grain size distribution. It is considered that the source of surface sediments in backside of sandbar were flowed in from Nakdong River. In order to verify the characteristics of inflowing sediments behavior, detailed surveys around Nakdong River Estuary need to be carried out, continuously.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.1
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• pp.1-12
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• 2007

Mooring survey for measurement of tidal current and suspended sediments was carried out at 4 inlets of Yeoja Bay in April, 2000 in order to understand the source of sediment supply. Net suspended sediment transport load during 2 tidal cycles through the M-1(West Inlet) was $133.88\;kg{\cdot}m^{-1}$ toward the Yeoja Bay, whereas the flux through the M-2(Jabal Inlet) was outward the Bay with the amount of $146.43\;kg{\cdot}m^{-1}$. The influx through the M-3 and 4(Bulgyo and Dong Isa Stream) was $23.25\;kg{\cdot}m^{-1}$ and $4,312.31\;kg{\cdot}m^{-1}$ toward the Yeoja Bay, respectively. Influx of suspended sediment on Yeoja Bay mainly occurred in the Dong Isa Stream. In the wet season the composition of surface was coarser-grained than dry season, possibly due to the influx of silty sediment from Dong Isa Stream In the wet season.

• Journal of the korean society of oceanography
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• v.39 no.4
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• pp.212-221
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• 2004

Concentrations of suspended particulate matters (SPM) and their distribution patterns were monitored three times in the East China Sea during the winter season in 1998 and 1999. SPM concentrations showed significant temporal variations controlled by the atmospheric conditions and sea states. In coastal area, SPM values were about 10-20 mg/l in fair weather conditions, but exceeded 100mg/l during the storm periods. Turbid waters were distributed widespread in the continental shelf of the East China Sea and the coastal area of the Korean Peninsula, and these two areas were connected along a NE-SW direction. The distribution patterns of turbid waters were interpreted as representing the transport behavior of suspended matter. Although the primary source of inner shelf mud deposits of Korea seems to be the Korean Peninsula, contribution from the East China Sea to the coastal area of Korea increases especially during the winter season.