• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3B
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• pp.205-209
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• 2011

The low carrying capacity caused by the deposition in a sewer line is one of the main reason of the urban flood. Therefore, an efficient maintenance and management of the storm water drainage system is very important to prevent urban flood. In this research, the sediment transport characteristics through a pressure pipeline were examined with laboratory experiments. Bed-forms in a pipeline, sediment rates, roughness due to sediments were examined. Experimental system consists of flow circulation system with a pump and a sediment feeder at the upstream of the pipeline. Sediments were supplied into a 60 mm-diameter and 8 m-long pipe. Maximum flow rate is $30m^3/hr$, and the sediment feeding rate range is 5 g/s~19 g/s. Governing parameters and estimation equation for sediment transport rate were developed. The mean velocity (U), coefficient of viscosity (${\mu}$), unit width bed load ($q_b$), mean diameter of particle ($d_{50}$), unit weight of sediment in water (${\gamma}^{\prime}_s$) were adopted as the most influencing factors of sediment transport patterns. The prediction equation for sediment transport rate were developed with two dimensionless terms. These two dimensionless terms showed a linear relationship with high correlation coefficient.

• Journal of Korea Water Resources Association
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• v.44 no.12
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• pp.975-990
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• 2011

In this study, to develop an assessment method for spatio-temporal riverbed changes, a 1-dimensional model (HEC-RAS) and a 2-dimensional model (CCHE2D) were built and applied. As for the analysis of a riverbed's long-term change in a real stream, three new assessment methods were developed, which are called the "Sediment section cumulative curve", "Sediment section moment", and "Sediment probability distribution function." These methods were used to assess the characteristics of riverbed changes using a consistent valuation standard and to understand changes in quantities intuitively. From the results of this study, sediment characteristics of cross sections can be detected effectively by applying the "Sediment section cumulative curve" method to determine whether there is any sedimentation or erosion in total emission. The amount of sedimentation or erosion occurring in the right or left banks, which divided by center column, could be presented as one criterion by applying the "Sediment section moment" method. This approach could be utilized as an indicator for sediment predictions. Spatio-temporal sediment variables can be presented quantitatively by determining the mean and uncertain boundaries through the "Sediment probability distribution function", and finally, the results can be illustrated for each cross section to provide intuitive recognition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.2
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• pp.385-394
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• 2007

To study long-term characteristics of the heavy metal contamination, soil and sediment samples were collected at 14 sites in highway roadside during 6 years. The total concentrations of metals including Zn, Ni, Cu. Pb, Cr, Cd, and As in those samples were investigated. The results indicate that concentrations of Zn, Ni, and Cu in highway roadside soils are much higher than the metal concentrations in background soils and appear to be increased gradually. Strong linear relationships between the cumulative traffic and the contents of the metals in highway roadside soils were obtained. Therefore, they might be used to predict the heavy metal concentrations in the future highway roadside soils for establishing the countermeasure of soil and sediment contamination.

• Journal of Environmental Impact Assessment
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• v.12 no.1
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• pp.9-22
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• 2003

To consider environmental characteristics in the scope of geochemistry of streams, Hwasun area, soil, sediment and water samples near/in the streams were analyzed in texture and metal contents of soil and sediment and in quality in water. From those analyses, the soils are loamy sand, sandy loam, loam and silty loam in texture. And, the sediments are slightly gravelly sand, gravelly sand and gravelly muddy sand in facies. Metal contents in soils and sediments are of high near Hwasuneup and Hwasun coalfield. In peculiar, P, Co, Li, Ni, Zn and Pb exceed over crust mean contents. Physico-chemistry of above streams according to pH-Eh and Piper's diagrams indicates that the streams are, typically, assigned to natural river water. Water qualities of BOD, T-N and T-P in areas near Hwasun coalfield, Dongmyeon and Hwasuneup are polluted over V level. Enrichment factor(EF) representing metal condensation in P, Cu, Zn and Pb appear near Hwasun coalfield and Hwasuneup from the soil and sediment samples, in part. Additionally, river water in dry season is very high in BOD, T-N, $Na^+$ and ${SO_4}^{2-}$. It is suggested that the relatively high metal contents in the stream be connected with above coalfield and urban areas.

• Korean Journal of Remote Sensing
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• v.25 no.3
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• pp.225-231
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• 2009

The characteristics of morphological shapes, wave heights, tidal ranges and sediment sizes are observed and compared between intertidal beach and mudflat. The Mohang sand beach, southwest coast of Korea, is located just next to the large mudflat and has tidal range over 5 meters. Wave measurements are conducted at each entrance of the beach and mudflat as well as at the outside waters representing the incident waves to these different coastal environments. The morphological characteristics are also examined including the sediment size and the slope of the bathymetry, For the observation of morphological shapes, camera monitoring technique is used to measure the spatial information of intertidal bathymetry. The water lines moving on the intertidal flat/beach durinq a flood indicate depth contours between low and high water lines. The water lines extracted from the consecutive images are rectified to get the ground coordinates of each depth contours and integrated to provide three dimensional information of intertidal topography. The wave data show that sand beach is in the condition of severer wave forcing but tidal range is almost identical in both environment. The slope of the mudflat is much milder than the sand beach with finer sediment.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.399-406
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• 1999

Recently, the construction of the several highway bridges in the karst area have encountered severe problems associated with cavities and sinkholes. To solve this problems, it is important to understand the distribution characteristics of cavities in the construction site on limestone area. This paper briefly describes the different types, the distribution control factors and the infill sediment types of lime-cavities in the study area, bridge site in the karst area and propose the effective method of survey design. Cavity system may be divided into two main groups, 1)'slot and cave system'and 2)'sinkhole and cave system'. And the shape, the size and the distribution pattern of cavity are controlled by three main factors - rock type, geological structure and ground water condition. Additionally, infill sediment may be considered as one of the important design factors for foundation design and divided into four types by sediment properties. There are geophysical thechnics and geologic survey and drilling test, etc. by the survey method to interpretate characteristics of cavity system, and this methods are optimally designed at the site investigation stage.

• The Korean Journal of Ecology
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• v.19 no.5
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• pp.365-373
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• 1996

A survey was carried out to investigate the contamination of streams by the acid mine drainage originated from the abandoned coal mines and coal refuse piles. The physico-KDICical characteristics such as pH, sulfate and elements concentrations in the water and sediment in streams were analyzed. Microbial activity in the sediment was evaluated by measuring dehydrogenase activities. At sites contaminated by acid mine drainage, the pH of the water and sediment declined to acidic range from neutral due to the accumulation of sulfate. The dehydrogenase activity ranged from 12 to $170{\mu}g-TPF{\cdot}g-dry\;soil^{-1}{\cdot}24h^{-1}$ at the contaminated sites, whereas uncontaminated sites had activities of 1,176~4,259 ${\mu}g-TPF{\cdot}g-dry\;soil^{-1}{\cdot}24h^{-1}$. The dehydrogenase activity was significantly affected by low pH of the sediment, indicating that high concentration of sulfate inhibited microbial activity. The concentrations of heavy metals such as Pb and Fe in contaminated sdeiment (37~46 ppm Pb; 46,000~464,000 ppm Fe) were much higher than those in the uncontaminated sediment. The concentration of Al in the contaminated water acidfied by coal mine drainage was in the range of 11 to 42 ppm. Compared with those in the uncontaminated sediment, the concentrations of Mn, Mg and Ca in contaminated sediment were low because of the leaching from soil to water by the acidfied stream water.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4B
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• pp.405-411
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• 2008

The Nakdong River Estuary Barrage (NREB) was constructed in 1987 to prevent saltwater intrusion and to provide the sustainable water supply in the upstream channel. Sediment dredging has been conducted to eliminate deposited sediments in the approached upstream channel of the NREB. Fluvial changes and sedimentation problems have been continued due to urbanization and development in the watershed as well as construction of the NREB. However, the sufficient field monitoring and researches for sedimentation characteristics and bed changes have not been performed after construction of the NREB. Therefore, bed elevation changes and seasonal sediment concentration distribution were analyzed using the quasi-steady state model with historical field data in this study. The water surface elevation changes with and without sediment dredging operation were calculated using the developed quasi-steady state model and finally the sediment dredging effects were evaluated.

• Journal of the Korean Society of Hazard Mitigation
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• v.1 no.3 s.3
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• pp.93-102
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• 2001

In this study, the characteristics of river bed profile fluctuation are become possible to be used effectively in future estimation of Taehwa river general development plan through analysis and examination according to the effects of sediment protection weir located in the area of the estuary of Taehwa river's main channel using HEC-6 model. The flow conditions needed in analysis of the characteristics of river bed profile fluctuation refer the conditions of flow which secures 95 days in a year, flood flow, and design flood examined in the estimation of Taehwa river maintenance basic plan. First, in analysis result of river bed variation range, there is no significant variation in upstream section from Samho-gyo while there are the more active erosion and sedimentation as the more flow in downstream from Samho-gyo. Next, from the result of the capacity of sediment transfer, it is analyzed that sediment transfer capacity in the area of estuary of Taehwa river has no significant difference in before and after removal of the sediment protection weir when design flood flows while it is estimated that the more flow, the bigger sediment transfer capacity. Therefore, it is thought that the installation of a suitable hydraulic structure at the lowest point of Dong-chun tributary joins from the downstream of Taehwa river can be a good device to reduce the accumulation of sediments at the lowest point of Taehwa river considering the reduction plan of sediment inflow caused by removal of the sediment protection weir.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.3
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• pp.103-111
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• 1998

This paper reports the sediment geochemistry and its relation to the grain size distribution in Kyeonggi Bay, Korea. Sediment samples were collected from 90 stations during the cruise crossing the bay in December 1995. Variables investigated were the sediment grain size, organic carbon content, and concentrations of AI, Fe, Mn, V, Co, Ni, Cr, Zn and Cu in the sediment. We followed the change in these variables by comparing the data obtained from this region in 1981. Distribution pattern of sediment grain size was modified from that in 1981 in some places. Near the Shihwa Dike which was completed in 1994, sediment had got finer grained. Sediment facies changed from fine to mixed facies near Youngjong Island where the tidal flat has been reclaimed for airport construction. Contents of organic matter and metals in the sediment were mostly dependent upon the sediment grain size, but an exception was found in the harbor area. The sediment in the Incheon North Harbor showed higher accumulation of organic matter and metals such as Ni, Cr, Zn and Cu.