• Title, Summary, Keyword: sediment

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Estimation of Coastal Suspended Sediment Concentration using Satellite Data and Oceanic In-Situ Measurements

  • Lee, Min-Sun;Park, Kyung-Ae;Chung, Jong-Yul;Ahn, Yu-Hwan;Moon, Jeong-Eun
    • Korean Journal of Remote Sensing
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    • v.27 no.6
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    • pp.677-692
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    • 2011
  • Suspended sediment is an important oceanic variable for monitoring changes in coastal environment related to physical and biogeochemical processes. In order to estimate suspended sediment concentration (SSC) from satellite data, we derived SSC coefficients by fitting satellite remote sensing reflectances to in-situ suspended sediment measurements. To collect in-situ suspended sediment, we conducted ship cruises at 16 different locations three times for the periods of Sep.-November 2009 and Jul. 2010 at the passing time of Landsat $ETM_+$. Satellite data and in-situ data measured by spectroradiometers were converted to remote sensing reflectances ($R_{rs}$). Statistical approaches proved that the exponential formula using a single band of $R_{rs}$(565) was the most appropriate equation for the estimation of SSC in this study. Satellite suspended sediment using the newly-derived coefficients showed a good agreement with insitu suspended sediment with an Root Mean Square (RMS) error of 1-3 g/$m^3$. Satellite-observed SSCs tended to be overestimated at shallow depths due to bottom reflection presumably. This implies that the satellite-based SSCs should be carefully understood at the shallow coastal regions. Nevertheless, the satellite-derived SSCs based on the derived SSC coefficients, for the most cases, reasonably coincided with the pattern of in-situ suspended sediment measurements in the study region.

Long-Term Shoreline Change and Evaluation of Total Longshore Sediment Transport Rate on Hupo Beach (후포해빈에서 해안선의 장기변화 및 전연안표사량의 추정)

  • Park, Il-Heum;Lee, Young-Kweon
    • Journal of Ocean Engineering and Technology
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    • v.21 no.4
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    • pp.15-20
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    • 2007
  • The harbor siltation by longshore sediment transports has become a serious problem on the East Coast of Korea. A reasonable prediction of the longshore sediment rate is important to approach the siltation problem effectively. In the recently developed 1-line model, the empirical constants of the sediment transport formula, which include the absolute quantity of sediment transport rate and the spatial distribution of breaking wave height by wave deformation, are treated as calibration parameters. Since these constants should be determined by the very long-term shoreline data, the longshore sediment rates are much more reasonable values. The method was applied to Hupo Beach, which has experienced heavy siltation. The authors also discuss long-term shoreline change using aerial photos and the observed wave-induced current patterns. According to the result, the SW-direction sediment transport rate was $146,892m^3/year$, and the NE direction was $2,694,450m^3/year$ at Hupo Beach for the last 11 years. The siltation in Hupo Harbor might be affected by the NE-direction sediment transport from Hupo Beach.

Enhanced Sediment Assessment Tool for Effective Erosion Control (효과적인 토양유실 방지대책 수립을 위한 유사평가툴)

  • Lim, Kyoung-Jae;Engel, Bernard A.;Choi, Ye-Hwan;Choi, Joong-Dae;Kim, Ki-Sung;Shin, Yong-Cheol;Heo, Sung-Gu;Lyou, Chang Won
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • pp.632-636
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    • 2005
  • Accelerated soil erosion is a worldwide problem because of its economic and environmental impacts. To effectively estimate soil erosion and to establish soil erosion management plans, many computer models have been developed and used. The Revised Universal Soil Loss Equation (RUSLE) has been used in many countries, and input parameter data for RUSLE have been well established over the years. However, the RUSLE cannot be used to estimate the sediment yield for a watershed. Thus, the GIS-based Sediment Assessment Tool for Effective Erosion Control (SATEEC) was developed to estimate soil loss and sediment yield for any location within a watershed using the RUSLE and a spatially distributed sediment delivery ratio. SATEEC was enhanced in this study by developing new modules to:1) simulate the effects of sediment retention basins on the receiving water bodies, 2) prepare input parameters for the Web-based sediment decision support system using a GIS interface. This easy-to-operate SATEEC system can be used to identify areas vulnerable to soil loss and to develop efficient soil erosion management plans.

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Characteristics of Benthic Chlorophyll a and Sediment Properties in the Tidal Flats of Kwangyang Bay, Korea

  • Sin, Yong-Sik;Ryu, Sang-Ock;Song, Eun-Sook
    • ALGAE
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    • v.24 no.3
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    • pp.149-161
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    • 2009
  • Characteristics of benthic microalgae and sediment properties were investigated for the intertidal flats of Kwangyang Bay, Korea. Sampling stations were selected every 100 m in the intertidal flats from land-side to open ocean at two different sampling sites. Samples were collected in June 2004, July, September, November, February and May 2005. Sediments properties were measured including temperature, water contents, sediment bulk density, nutrient concentrations in porewater. Chlorophyll a concentrations in surface sediment (0.5 cm) were measured and relationships between the chlorophyll a and various sediment properties were analyzed to identify major mechanisms regulating biomass of benthic microalgae in the intertidal flats using simple linear regression analysis. Sediment chlorophyll a concentrations were maximum during winter and minimum during warm seasons ranging from 4.4 mg $m^{-2}\;to\;81.2\;mg\;m^{-2}$. No clear spatial variations were observed for the sediment chlorophyll a in the study sites. Results from regression analysis suggested that benthic microalgae biomass was affected by sediment temperature and nutrients especially ammonium and silicate. Grazing effect was estimated using chlorophyll: pheopigments ratio, indirect indicator of grazing activity, and the positive correlation of the ratio and chlorophyll a implied that microalgae biomass is affected by grazing of zoobenthos although direct measurement of grazing activity is required to determine the importance of top-down controls in the benthic microalgae dynamics.

Simulation of Sediment Deposition Behavior in a Reservoir using a SED2D model: Focusing on Sensitivity of Simulation Time Step (SED2D모형을 이용한 저수지 퇴사거동 모의-모의시간간격의 민감도를 중심으로)

  • Kim, Dae Guen
    • Journal of Korean Society of Water and Wastewater
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    • v.26 no.1
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    • pp.87-95
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    • 2012
  • In this study, the following conclusions were obtained from an investigation of the effect of the simulation time step on the simulation results of the two-dimensional, vertically averaged sediment transport model SED2D and an analysis of the deposited sediment distribution in suspended sediments of reservoirs according to grain size. The simulation time step has a significant effect on the deposited sediment distribution in a reservoir. In particular, if the simulation time step is set to be excessively large, physically invalid results are obtained. Additionally, in order to determine an appropriate simulation time step for SED2D, the selection of a simulation time step that will allow the analysis of the suspended sediment concentration profile at the main points of the simulation domain is necessary. The deposited sediment distribution in a reservoir according to grain size, including suspended sediments of clay, silt, and sand, was successfully simulated. Such information will prove valuable in application to the establishment of efficient management and reduction measures of reservoir sediment deposits.

Activated Carbon Performance for the Treatment of Diesel-Derived Polycyclic Aromatic Hydrocarbons

  • Choi, Yongju;Luthy, Richard G.
    • Ecology and Resilient Infrastructure
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    • v.2 no.2
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    • pp.177-184
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    • 2015
  • This study assessed the performance of activated carbon (AC) amendment to treat polycyclic aromatic hydrocarbons (PAHs) including both parent- and alkylated-moieties in sediment impacted by diesel. A field-collected, diesel-impacted sediment with a NAPL content of 1% was used for the study. No. 2 diesel fuel is weathered by heating at $70^{\circ}C$ for 4 days to obtain a weathered diesel sample having C3-naphthalenes to C2-phenanthrenes/anthracenes (N2/P3) ratio similar to the original sediment. The sediment samples spiked with the weathered diesel to obtain non-aqueous phase liquid (NAPL) contents of 1, 5 and 10% were contacted with AC with a dose of 5% as sediment dry weight for 1 month. By the AC-sediment contact, the freely-dissolved equilibrium concentrations were substantially reduced. Even for sediment with 10% NAPL content, the reductions in the freely-dissolved concentrations were 92% and 75% for total parent-and alkylated-PAHs, respectively. The effect of NAPL contents on the performance of AC was negligible for parent-PAHs, while for alkylated-PAHs, a slightly reduced AC performance was observed. The results suggest that the AC amendment can be an effective option for the treatment of petroleum-impacted sediment with relatively high NAPL contents.

Prediction of Sediment according to Type of Rural Canal (농촌용 수로의 유형에 따른 토사 퇴적량 예측)

  • Song, Chang Seob;Lim, Seong Yoon
    • Journal of The Korean Society of Agricultural Engineers
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    • v.56 no.6
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    • pp.121-128
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    • 2014
  • Development of the economic methods and the design of the standard sections needs the more project fund and land than ever leads to the objection of enlarging canal arrangement to need economic construction method development and standard design for supporting it. 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 land types (Mountain, Flatten, Reclaimed land). This study was carried out to analysis for the soil loss and sediment of drain and irrigation by comparing RUSLE method and amount of sediment from amount of dredging data of Korea Rural Corporation. The results of study were analyzed and summarized as follow. Size of soil sediment from the upper region of drain and irrigation of mountains bigger than lower region. But in case of flatten and reclaimed land, size of soil sediment from the upper and lower region of drain and irrigation did not classified. In case of comparison drain and irrigation without classifying of land type, size of soil sediment from irrigation is bigger than drain.

The Evaluation on Solidification of Dredged Sediment for Recycle from Stagnant Water Area (정체성 수역 퇴적물 재활용을 위한 고형화 평가)

  • Kim, Sang Hyun;Ahn, Tae Woong;Choi, I Song;Oh, Jong Min
    • Journal of Environmental Impact Assessment
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    • v.21 no.1
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    • pp.63-69
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    • 2012
  • Sediment has been increasingly acknowledged as a carrier in water system and an available contamination. For this reason, dredging of sediment in reservoir to remediate water quality and secure storage capacity is conducted annually. However, disposal of numerous dredged sediment is necessary as a secondary problem. Currently, in Korea, dredged sediment is classified as waste to be reclamated or recycled into sandy soil, however, they are still in trouble because of spacial and environmental problem. Therefore, rather than simple disposal or reuse into sandy soil, it is necessary to research on method to manage main cause of pollution and increase the value as a resource. In this study, we intend to develop a recycle technology for numerous dredged sediment produced by dredging in deteriorated reservoirs using solidificator (stabilizer). To achieve this, we will consider utilization of dredged sediment and evaluation of use possibility as natural recycle by analysis the characteristics of soil-solidificator mixture in terms of physicochemical properties and the mixing ratio between sediment and solidificator.

Susceptibility of Nereocystis luetkeana (Laminariales, Ochrophyta) and Eualaria fistulosa (Laminariales, Ochrophyta) spores to sedimentation

  • Deiman, Melissa;Iken, Katrin;Konar, Brenda
    • ALGAE
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    • v.27 no.2
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    • pp.115-123
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    • 2012
  • The establishment of algal spores plays an essential role in adult kelp distribution and abundance patterns. Sedimentation is a key variable regulating algal spore settlement and success, possibly controlling species-specific dominance $in$ $situ$. Laboratory experiments were used to determine spore attachment and survival rates of two Alaskan canopy-forming kelps, $Nereocystis$ $luetkeana$ (K. Mertens) Postels & Ruprecht and $Eualaria$ $fistulosa$ (Postels & Ruprecht) M. J. Wynne, to various types of sediment loading. Spore attachment for both species was significantly and similarly affected by three sediment treatments: suspended particles; settled sediment covering the substratum; and smothering of attached spores by settling sediment. Spore attachment decreased by approximately 90% at 420 mg sediment $L^{-1}$, the highest sediment load tested here, under all three treatments for both species. These results suggest that increases in sedimentation may constrain the success of the spore stages, but sediment does not seem to be a likely factor explaining species-specific distribution patterns. However, while sedimentation affected spores of both species similarly, timing of spore release in relation to times of maximum sediment load in the water might differ for different species, possibly explaining kelp species distribution patterns.

Turbidity Meter Calibrations Based on Grain Size Distribution of Trapped Suspended Material (포획된 부유물질의 입도분포를 고려한 탁도계 검교정)

  • 조홍연;김백운
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.15 no.1
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    • pp.33-38
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    • 2003
  • Turbidity meter calibrations were conducted using bottom sediment and suspended material collected with a vertical array of sediment traps at the coastal water off Gaduk Island. Compared to the bottom sediment comprising sand fraction of approximately 6%, trapped suspended material was composed entirely of silt and clay fractions and showed a tendency to get finer as elevation from the sea-bed increases. Slope parameter of linear regression due to bottom sediment was of minimum value and values of those due to suspended material increased gradually as the height of sediment trap increases (i.e., sediment size decreases). This result shows that turbidity meter calibration using bottom sediment can cause an overestimation error in the calculation of suspended sediment concentration and that the error can reach up to 25% in case of this study. Therefore, it is suggested that the use of a corrected calibration curve based on grain size distribution of suspended material instead of bottom sediment may reduce the measurement error of suspended sediment concentration.