• Title, Summary, Keyword: sediment

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Examination of Vertical 1D Sediment Resuspension and Diffusion Model Using Field Data Collected in the Saemangeum Area (새만금 해역에서 연직 1차원 퇴적물 확산모델 검증)

  • Lee, Guan-Hong;Lee, Hee-Jun
    • Ocean and Polar Research
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    • v.30 no.4
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    • pp.537-543
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    • 2008
  • The sediment resuspension and diffusion model is an integral part of a sediment transport and morphologic change model. We examined a vertical one-dimensional sediment resuspension and diffusion model using field data collected at about 10-m depth off the Saemangeun $4^{th}$ dike. The field data include waves, currents and suspended sediment concentration near the bed for about a day in May, 2007. The suspended sediment concentration obtained from the 1D model overestimated the observation about two orders of magnitude with single grain size and multiple grain sizes. The incorporation of the bed armoring effect, which adjusts the amount of suspended sediment with the available bed sediment, improved the agreement between the model and observation within a factor of two.

Application of a Sediment Quality Index to the Masan Bay, Korea

  • Shim, Won-Joon;Hong, Sang-Hee
    • Ocean and Polar Research
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    • v.29 no.4
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    • pp.367-378
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    • 2007
  • A sediment quality index (SQI) and a mean sediment quality guideline quotient (M-SQGQ) were applied for the assessment of sediment quality in Masan Bay, Korea where metals and organic pollutants are of concern. The SQI was calculated by two functions, 'scope' (the number of variables that do not meet guideline objective) and 'amplitude' (the magnitude by which variables exceed guideline objective), with six different sediment quality guideline values from Canada, USA and Australia/New Zealand. Categorization of sediment quality was on the basis of SQI scores. The SQI values were compared with six guideline values applied as well as with the M-SQGQs. The SQI values were severely influenced by a few variables of high exceedance in the degree of non-compliance. The SQI values were very dependent on both the numbers and values of guideline variables used in index caluculation. Nevertheless, the SQI could provide integrated and simplified information from a large number of chemical data set. It is required to further evaluate protocols and guideline applied for deriving SQI and to compare it with field based sediment toxicity test and ecosystem integrity.

Estimating Temporal and Spatial Variation of Sediment Transport Processes using a Distributed Catchment Model (분포형 유역모델을 이용한 유사 운반과정의 시·공간적 변동 해석)

  • Koo, Bhon K.;Cho, Jae-Heon
    • Journal of Korean Society on Water Environment
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    • v.23 no.6
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    • pp.872-880
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    • 2007
  • For effective management of sediment-related diffuse pollution, it is of utmost importance to estimate spatial variation of sediment transport processes within a catchment. A mathematical model can play a critical role in estimating sediment transport processes at the catchment scale provided that the model structure is appropriate for representing major sediment transport processes of the catchment of interest. This paper introduces a distributed catchment model River Basin Water Quality Simulator (RBWQS) and presents some results of its application to a small rural catchment in Korea. The model has been calibrated and validated for a wet period using hourly hydrographs and sediment concentrations observed at the catchment outlet. Based on the model simulation results, the spatial variation of sediment transport processes across the catchment and the effects of paddy fields and small reservoirs on hydrology and sediment transport have been analyzed at the catchment scale.

Research on the Sediment Characteristics in Change Structural Shape of Agricultural Irrigation (농업용수로 구조적 형상 변화에 따른 퇴적 특성 연구)

  • Park, Jung Koo;Kim, Myeong Hwan;Song, Chang Seob
    • Journal of The Korean Society of Agricultural Engineers
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    • v.57 no.6
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    • pp.69-77
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    • 2015
  • The objective of this study was to evaluate the performance of selected sediment reduction methods to reduce sediment discharges from drain and irrigation of different types (concrete canals, soil canals). This study was carried out to analysis for the suspended sediment concentration and sediment of drain and irrigation by velocity of flow. The results of study were analysised and summerized as follow. Sedimentation characteristics and size of soil sediment from the concrete and soil canals of downstream smaller than upstream. Suspended sediment concentration and flow times from the suggestion canals bigger than open canal. Structural shape of the canal decreases the velocity of flow also affects the suspended sediment concentration and flow times.

A Study on Relationship between Point Load Strength Index and Abrasion Rate of Sediment Particle (퇴적물 입자의 점하중강도지수와 마식율의 관계에 대한 연구)

  • Kim, Jong-Yeon
    • Journal of the Korean Geographical Society
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    • v.43 no.6
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    • pp.808-823
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    • 2008
  • Sediment abrasion in rivers is caused by the interaction between bedrock channel bed and sediment particles transported through the river. Abrasion rate of sediment particles in rivers is controlled by two major factors; Sediment transport conditions including hydraulic conditions form the erosive forces and physical and chemical strengths of the particles form a resistance force against abrasion and other erosional processes. Physical experiments were performed to find the role of each variable on sediment abrasion process. Total 266 sediment particles were used in this experiment. All sediment particles were divided into 11 independent sediment groups with sediment particle size and sediment loads. Each sediment groups were abraded in tumbling mill for up to 8 hours. Changes in weight were recorded by run and total: 2,128 cases of abrasion rate were recoded. Physical strength of rock particles was measured with point load strength index. It is found that sediment abrasion rate has a negative functional relationship point load strength index ($I_{a(50)}$) ($R^2=0.22$). It was suggested that physical strength of sediment particles set the "maximum possible abrasion rate'. As sediment flux increases, abrasion rates of sediment particles with similar point load strength index were changed. It could be concluded that not only physical characteristics of sediment particles, but also sediment transport conditions control sediment abrasion rates.

A Study on Estimate of Sediment Yield Using Tank Model in Oship River Mouth of East Coast (Tank 모형을 이용한 동해안 오십천 하구의 유사량 평가에 관한 연구)

  • Kang, Sank-Hyeok;Ok, Yong-Sik;Kim, Sang-Ryul;Ji, Jeong-Hwan
    • 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.

A study on the Sediment Disaster Response System in Japan (일본의 토사재해 대응체계에 대한 연구)

  • Lee, Woo-Jin
    • Journal of Digital Convergence
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    • v.16 no.7
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    • pp.47-54
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    • 2018
  • Sediment disaster happen frequently in our country every year, and a lot of lives and the properties have been lost because of them. Non-structural measures for prevention of sediment disaster have been introduced by prefectures based on the Sediment-related Disaster Prevention Law established after the devastating rainstorm damage in Hiroshima in 1999. They include formulation of sediment disaster warning and evacuation standard rainfall and designation of sediment disaster warning zones and sediment disaster special warning zones. As a practical example, this research focused on the case of "TEC-FORCE" of "MLIT of Japan" as a method of utilizing professional workforce and the sediment disaster warning information delivery system in Kagoshima. In the future, it will be called for prevention and reduction of damages by utilizing professional workforce and sediment disaster response system such as Japan.

An Experimental Study on the Sediment Transport Characteristics Through Vertical Lift Gate (연직수문의 퇴적토 배출특성에 관한 실험적 연구)

  • Lee, Ji Haeng;Choi, Heung Sik
    • Ecology and Resilient Infrastructure
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    • v.5 no.4
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    • pp.276-284
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    • 2018
  • In order to analyze sediment transport characteristics of knickpoint migration, sediment transport length, and sediment transport weight through the under-flow type vertical lift gate, the hydraulic model experiment and dimensional analysis were performed. The correlations between Froude number and sediment transport characteristics were schematized. The multiple regression formulae for sediment transport characteristics with non-dimensional parameters were suggested. The determination coefficients of multiple regression equations appeared high as 0.618 for knickpoint migration, 0.632 for sediment transport length, and 0.866 for sediment transport weight. In order to evaluate the applicability of the developed hydraulic characteristic equations, 95% prediction interval analysis was conducted on the measured and the calculated by multiple regression equations, and it was determined that NSE (Nash-Sutcliffe Efficiency), RMSE (root mean square), and MAPE (mean absolute percentage error) are appropriate, for the accuracy analysis related to the prediction on sediment transport characteristics of kickpoint migration, sediment transport length and weight.

Applicability Evaluation to Grid-based Rainfall-Runoff-Sediment Model for Sediment Discharge Estimation (격자기반 강우-유출-유사 모형의 유사량 산정에 관한 적용성 평가)

  • Choi, Hyun Gu;Park, Jun Hyung;Han, Kun Yeun
    • Journal of Wetlands Research
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    • v.19 no.1
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    • pp.132-143
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    • 2017
  • It is essential to obtain periodic sediment discharge data in a river in order to minimize problems that may arise from the erosion, transport, and deposition of sediment. However, it is difficult to estimate sediment discharge by the sediment discharge measurement plan in Korea at present, and empirical fomulas or numerical models are used to replace them. This paper has applied the K-DRUM model, a grid-based rainfall-runoff-sediment model, to estimate sediment discharge and ensure the continuity of the data in the watershed. Discharge and sediment load in 17 watersheds were estimated and the applicability of the model was analyzed through comparisons with measured data. For quantitative evaluation, NSE, PBIAS and RSR items were used, and discharge results reflected the tendency of rainfall and showed high statistical value. In case of sediment discharge, the soil erosion process of the watershed is physically well reflected. When the calibration was performed using the measure data, the applicability seems to be excellent in estimating the continuous sediment discharge data in the real watershed.

Distribution of heterotrophic bacteria and physico-chemical characteristics of sediments in Kum river estuary (금강 하구 퇴적토의 이화학적 성질과 종속영양세균의 분포에 관하여)

  • 이건형;아영칠;홍순우
    • Korean Journal of Microbiology
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    • v.24 no.3
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    • pp.308-316
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    • 1986
  • Vertical distribution of heterotrophic bacteria and physico-chemical characteristics were measuted in Kum River estuarine sediments. And interrelationship between heterotrophic bacterka and environmental factors was also studied. The type of sediment of Site 1 was silty clay, and sand at Site 2. Annual pH ranges were between 7.1 and 7.7 in the clay type sediment (Site 1) and 6.9-7.2 in the sand type sediment (Site 2). It was shown that organic matter contents were higher in the clay type sediment than those of sand type sediment. Redox potential values of sediments were decreased rapidly with depth at Site 1, but those of Sete 2 showed vertical fluctuation. Nitrogens(ammonia+amino acid-N, nitrate-N, nitrite-N) and phosphate in the clay type sediment showed higher values than those of sand type sediment. Annual distribution of heterotrophic bacteria were ranged $6.71{\times}10^4$ cells/g dry wt. $-2.50{\times}10^6$ cells/g dry wt. In the clay type sediment and $2.67{\times}10^3$ cells/g dry wt. $-1.94{\times}10^6$ cells/g dry wt. in the sand type sediment. Distribution of proteolytic, lipolytic, and amylolytic bacteria were decreased with the depth and the highest density was found in April and the lowest in January. Bacterial populations in sediments were closely correlated with such environmental factors as pH, redox potential, moisture content, organic matter contents, and inorganic nutrients such as nitrite-N and phosphate-P.

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