• Ocean Systems Engineering
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• 제14권2호
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• pp.101-114
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• 2024

Seafloor sediment mapping is an essential research topic in shallow coastal waters, especially in port development, benthic habitat mapping, and underwater communications. The seafloor sediments can be interpreted by collecting sediment samples directly in the field using a grab sampler or corer. Another method is optical, especially using underwater cameras and videos. Both methods each have weaknesses in terms of area coverage (mechanic) and accurate positioning (optic). The latest technology used to overcome it is the acoustic method (echosounder) with Global Navigation Satellite System (GNSS) Real Time Kinematic (RTK) positioning. Therefore, in this study will propose the classification of seafloor sediments in coastal waters using acoustic method that is Multibeam Echosounder (MBES) multi-frequency with five frequency (200 kHz, 250 kHz, 300 kHz, 350 kHz, and 400 kHz). In this study, the deep neural network (DNN) used the bathymetric multi frequency, bathymetric difference inters frequencies, and bathymetric features from 5 (five) frequencies as input layer and 4 (four) sediment types in 74 (seventy-four) sample sediment as output layer to make a seafloor sediment map. Results of sediment mapping using the DNN method show an overall accuracy of 71.6% (significant) and a kappa coefficient of 0.59 (moderate). The distribution of seafloor sediment in the study area is mainly silt (41.6%), followed by clayey sand (36.6%), sandy silt (14.2%), and silty sand (7.5%).

• 한국지하수토양환경학회지:지하수토양환경
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• 제22권5호
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• pp.82-88
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• 2017

Contaminated sediment can be treated in order to reuse the treated sediment. Even though the chemical criteria are satisfied, the treated sediment could still impose toxic effects. Therefore, this study investigated the changes in the ecological toxic effects of the contaminated sediment from the J region in Singapore after treatment. The contaminated sediment was subject to sequential soil washing and thermal treatment, followed by pH neutralization. Toxic effects of the contaminated and treated sediments were determined by using Vibrio fischeri ($Microtox^{(R)}$), Triticum aestivum (wheat), and Eisenia foetida (earthworm). After treatment, the concentrations of total petroleum hydrocarbons and heavy metals were decreased by 98% and 59-93%, respectively, and satisfied the Industrial Maximum Values of the Dutch Standard, which were used as the remedial goal. The bioluminescence reduction of V. fischeri decreased significantly, and the earthworm survival increased from 0% to 90% after treatment. The germination rate increased from $0{\pm}0%$ to $75{\pm}13%$ after treatment, but the treated sediment may need additional treatment such as nutrient addition for better plant growth. Overall, this study showed that the treatment of the contaminated sediment satisfactorily removed mixed contaminants, and this led to reduction in toxic effects, suggesting improved potentials for reuse of the treated sediment.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2009년도 학술발표회 초록집
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• pp.752-757
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• 2009

In the last decade, many methods such as greet chamber, reservoir, or debris barrier, have been utilized to manage and prevent muddy water problem. The Vegetative Filter Strip (VFS) has been thought to be one of the most effective methods to trap sediment effectively. The VFS are usually installed at the edge of agricultural areas adjacent to stream or drainage ditches, and it has been shown that the VFS effectively removes pollutants transported with upland runoff. But, if the VFS is installed without any scientific analysis of rainfall-runoff characteristics, soil erosion, and sediment analysis, it may not reduce the sediment as much as expected. Although Soil and Water Assessment Tool (SWAT) model has been used worldwide for many hydrologic and Non-Point Source Pollution (NPSP) analysis at a watershed scale. but it has many limitations in simulating the VFS. Because it considers only 'filter strip width' when the model estimates sediment trapping efficiency, and does not consider the routing of sediment with overland flow option which is expected to maximize the sediment trapping efficiency from upper agricultural subbasin to lower spatially-explicit filter strip. Therefore, the SWAT overland flow option between landuse-subbasins with sediment routing capability was enhanced with modifications in SWAT watershed configuration and SWAT engine. The enhanced SWAT can simulate the sediment trapping efficiency of the VFS in the similar way as the desktop VFSMOD-w system does. Also it now can simulate the effects of overland flow from upper subbasin to reflect the increased runoff volume at the receiving subbasin, which is what is occurring at the field if no diversion channel is installed. In this study, the enhanced SWAT model was applied to small watershed located at Jaun-ri in South Korea to simulate diversion channel and spatially-explicit VFS. It was found that approximately sediment can be reduced by 31%, 65%, 68%, with diversion channel, the VFS, and the VFS with diversion channel, respectively.

• 한국수산과학회지
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• 제46권4호
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• pp.454-466
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• 2013

To evaluate the organic matter and trace metal pollution in intertidal sediment of the coastal zone, various geochemical parameters (grain size, ignition loss [IL], chemical oxygen demand [COD], acid volatile sulfide [AVS], and metals [Al, Fe, Cu, Pb, Zn, Cd, Cr, Mn, Hg, and As]) were measured for the intertidal surface sediment of the mainland and islands between Mokpo and Haenam in the southwestern coast of Korea. The surface sediments consist mainly of finer sediments, such as mud and silt. The concentrations of IL, COD, and trace metals in intertidal sediment were relatively high in the shoreline of the mainland than in that of islands and those in some stations exceeded the sediment quality guidelines (SQGs). Moreover, the concentrations of IL, COD, and trace metals (except As) in sediment showed relatively good positive correlations with mean grain size, indicating that the concentrations of organic matter and trace metals in intertidal sediment of the study region are dependent on grain size of sediment. Pollution evaluation for trace metals using geochemical assessment techniques, such as enrichment factor, geoaccumulation index, and SQGs, suggested that the intertidal sediments in the study region show light pollution with Cr and moderate pollution with As. More extensive interdisciplinary studies are required to determine the potential causes of As pollution in intertidal sediment.

• 한국수자원학회논문집
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• 제48권1호
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• pp.1-8
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• 2015

본 논문에서는 지난 20여 년간의 낙동강 하상변동 자료와 준설 및 골재채취 자료, 그리고 지류로부터 유입되는 유사량 관측 자료 및 수치모의 자료 등을 조사, 검토, 분석하여 4대강살리기 사업 전의 낙동강 하도에서의 개괄적인 유사수지 특성을 분석하였다. 4대강살리기 사업 전 낙동강 하도의 유사수지분석 결과, 유역에서 하도로 유입된 유사량은 $2,100,000m^3/yr$이며 낙동강으로부터 유출 또는 준설된 유사유출 총량은 $10,180,000m^3/yr$인 것으로 나타났다. 따라서 유사수지 분석을 통해 산정된 낙동강 하도에서의 하상변동량은 $-8,080,000m^3/yr$으로 하상이 침식된 것으로 나타났으며 이는 실제 하도측량 자료 분석을 통해 도출된 낙동강 본류의 자연적 그리고 인위적인 하상변동량($-8,300,000m^3/yr$)과 유사한 것으로 나타났다.

• 생태와환경
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• 제42권4호
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• pp.413-421
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• 2009

Eleven lake sediment core samples were obtained and analyzed to develop a chronology using $^{137}Cs$ (in 1963) and two tephra layers (Ko-c2 in 1694 and Ta-a in 1739). Sedimentation rates estimated for the past ca 300 years in Lake Shirarutoro indicated that catchment development has influenced the shallowing process in the lake by increasing sediment production. The sediment yield under initial land-use development conditions for the first two periods was estimated as 514 tons $yr^{-1}$ from 1694 to 1739 and 542 tons $yr^{-1}$ from 1739~1963. The development of the Shirarutoro catchment intensified in the 1960s with deforestation and agriculture activity leading to an increased sediment yield of 1261 tons $yr^{-1}$ after 1963. The sediment yields after intensified land use development, such as forestry and agricultural development, were about 2 times higher than that under initial development conditions, leading to accelerated lake shallowing over the last ca 50 years. Sedimentation rates differed with location in the lake because of spatial variation in the sediment flux from the contributing rivers and their catchments. The sedimentation rates before 1963 were low in all sites except for one site close to the Shirarutoroetoro River. The sedimentation rate in 1739~1963 was accumulated mostly at the inflow of the Shirarutoroetoro River by sediment production associated with forestry for charcoal production and initial agricultural development. The sedimentation rate after 1963 increased. In particular, the southern zone of the lake near the conjunction with the Kushiro River had a high sedimentation rate, which is attributable to sediment inflow back from the Kushiro River during floods.

• 한국축산시설환경학회지
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• 제20권4호
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• pp.195-200
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• 2014

Liquid fertilization of pig manure slurry is very useful treatment method to recycle organic waste matter as a valuable fertilizer. The solids precipitate and accumulated at the bottom of liquid fertilization tank. The content of nitrogen and phosphate are higher in sediment than pig manure slurry. The pH of sediment was 7.53. S-COD/T-COD ratio of pig manure slurry and sediment were 0.477, 0.29, respectively. The moisture content of sediment of pig manure slurry and sediment were 80.45~83.82%, 97%, respectively. The content of organic matter of sediment was 8.79~10.56%. The content of nitrogen and phosphate of sediment and pig manure slurry were 9,000~11,100 mg/L, 9,100~11,100 mg/L, respectively. The particle size of pig manure slurry was distributed from 2 mm to 0.125 mm. On the other hand. the particle size of sediment was under 0.125 mm.

• 한국습지학회지
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• 제16권2호
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• pp.221-233
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• 2014

유수에 의한 하천 유역과 하천의 토양의 침식, 유송, 퇴적 현상은 빈번하게 발생한다. 이러한 과도한 현상은 수공구조물의 안전위협, 홍수범람 등의 자연재해를 가중시킨다. 토양침식에 따른 토사재해를 방지하기 위해서는 가장 우선적으로 정확한 유사유출량을 예측할 필요가 있다. 이를 위해서는 유역특성에 적합한 모형의 선정, 관련인자의 정량적인 산출, 가용 수문자료의 확보는 매우 중요하다. 따라서, 본 연구의 목적은 실측자료를 확보하고 있는 설마천 시험유역의 강우량, 유출량, 유사량 자료를 이용하여 강우-유출거동에 따른 토양침식량과 유사유출량을 산정하는데 있다. 그리고 유사전달률 분석을 통하여 설마천 시험유역의 유사전달률을 제안하였다. 향후에는 타 유역에도 적용하여 다양한 조건에서의 토양침식량 및 유사유출량 산정방법의 정형화, 유역 특성별 유사전달률 산정 연구를 하고자 한다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2010년도 학술발표회
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• pp.1739-1744
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• 2010

하천에서 유사이송 및 하상변동을 예측하는 여러 방법들 중 수치모형을 이용하는 방법이 현재 가장 많이 이용되고 있으며 특히 단일 유사량 산정 공식과 유사이송 형태를 현장자료와의 검증과정 없이 대부분 그대로 적용하고 있는 실정이다. 수치모형을 이용한 특정 대상하천의 정확한 하상변동 예측을 위해서는 유사량 산정 공식 및 유사 이송 형태에 따른 하상변동 민감도 분석 및 모형 검증과 검정 작업이 반드시 필요하며 이러한 과정을 통해 대상하천에 대한 최적의 유사량 산정 공식과 유사 이송 형태를 선정해야 할 것이다. 본 연구는 실제하천을 대상으로 여러 유사량 산정 공식과 유사 이송 형태를 다르게 적용이 가능한 CCHE2D 모형을 이용하여 하상변동 수치모의를 수행하였다. 유량 크기별 모의조건을 적용하여 하상변동 민감도를 분석을 통해 대상하천에서 적합한 유사량 공식과 이송 형태를 선정하고 실제수문사상의 유량 및 수위 조건을 적용하여 모의를 수행한 결과와 대상 하천에서 측량한 단면과 비교하여 검정을 실시하였다.

• 환경영향평가
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• 제21권1호
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• pp.81-91
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• 2012

In this study, it is grasped the status of nutrients through an investigation of release characteristics and physicochemical properties of sediments on reservoir. And then the effect of sediments is evaluated on the water quality in reservoir. In the results of physicochemical analysis, the pollution level of midstream is the highest, which shows the traits that the water is more deeper and takes place a deposition consistently. Then, the pollution level of upstream is higher than downstream's because inflow has influence on the upstream directly. The downstream is located near tidal gate so that the soil particles can be moved easily and are difficult to be deposited due to the distribution of seawater by control of tidal gate. Therefore, the downstream is showed the lowest pollution level than the others. Also, the concentration of SOD(Sediment Oxygen Demand) in the upstream which is influenced on the effect of inflow is highest than the others. When it analyzes under anaerobic and aerobic condition to understand the release characteristic of sediment, it shows that the release rate is low or negative under the aerobic condition. Whereas the release rate is usually positive under the unaerobic condition relatively. According to these results, it is necessary to maintain the proper environmental factors of water body for decreasing the release rate of sediment. Because the release rate is changeable under the different condition of water body. Therefore, proper strategies are required for increasing the self-purification of water as well as keeping the aerobic condition of sediment and managing a sediment layer directly to control the inner-pollution by the sediment of reservoir.