• Journal of Korea Water Resources Association
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• v.49 no.12
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• pp.971-980
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• 2016

In general, efficient operation of sediment sluicing is important in economical aspect. In this study, the efficiency of sediment sluicing by various operation at water surface elevation on multi-functional weirs were analyzed using Nays2DH, and we focused on the Dalsung weir at Nakdong river. The results of this study shows that, the same number of flushing channels and water gates were developed due to sediment sluicing, and sediment deposition occurred in upstream region of flushing channels. Also, the sediment sluicing efficiency increased by approximately 4.6% and sedimentation decreased by approximately 4.5% at EL. 14.5 m for operations on water surface elevation exceeding EL. 14.0 m. The mitigation of reservoir sedimentation and extension of maintenance dredging period are possible if the variation of sediment sluicing efficiency in various operation at water surface elevation during flood season are considered.

• Journal of Korea Water Resources Association
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• v.31 no.1
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• pp.95-103
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• 1998

Dam sediment can be predicted from the two methods: the one is a physical analysis based on the hydrjulic mechanism and the other is an empirical approach using observed data as a design factor. The former can be used to estimate short-term phenomena by mathematical methods. the latter can be used for deriving long-term design parameters such as dead storage calculation. Monthly reservoir operation is possible with the sluicing efficiency curve based on empirical data. The optimal sediment management can be carried out using the information variable which traces deposit sediments corresponding to the reservoir storage. The idea can provide an optimal operation strategy to save effective storage varying with time. This study presents a methodology for the long-term sediment prediction using sluicing efficiency curve. An application is conducted for estimating accumulated sedment deposit and water supply capability ofr the Fenhe dam in the Yellow rever of China.

• International Journal of Ocean System Engineering
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• v.2 no.2
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• pp.71-81
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• 2012

Several methods have been proposed to control the sedimentation process. These include catchment management, flushing, sluicing, density current venting, and dredging. Flushing is used to erode previously deposited sediments. In pressurized flushing, the sediment in the vicinity of the outlet openings is scoured and a funnel shaped crater is created. In this study, the effect of localized vibrations in the sediment layers on the dimensions of the flushing cone was investigated experimentally. For this purpose, experiments were carried out with two bottom outlet diameters, five discharge releases for each desired water depth, and one water depth above the center of the bottom outlets. The results indicate that the volume and dimensions of the flushing cone are strongly affected by localized vibrations.

• Journal of Korean Society on Water Environment
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• v.22 no.6
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• pp.1094-1100
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• 2006

In this study, the reservoir sediment reduction methods for long-term operation are proposed by the analysis of both sediment deposit characteristics and sediment reduction effect by each method. To that end, a flowchart for sediment analysis in reservoir is established and sediment deposit is simulated by SMS-SED2D model. The sediment reduction methods which are sediment passing (sluicing), flushing, trapping, bypassing and mechanical removal are used. From the simulation results, the effective method for sediment reduction is operation which is coupled by both sediment passing with sand gate and sediment trapping with debris dam. And If sediment flushing will be used once a year after 50 years, conservation storage can be secured until 100 years after dam construction.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.168-172
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• 2009

Shihmen reservoir was started in May 1963. The main purposes of Shihmen reservoir are for agriculture, power supply, flood control and tourism. Shihme Asn dam is an earth dam. Its crown height is 133m above mean sea level, with length 360 m, watershed 763.4 km², and maximum volume 309 million cms. Turbidity in Shihmen dam was severely affected by typhoons Aere (2004) and Masa (2005). Increased deposition after Aere was 28 million cms. Turbidity at Shihmen Canal Inlet is 3000 NTU (Nephelometry Turbidity Unit). Sediment sluicing strategies for downstream channel are demanded. Therefore, diversionary sediment preventing channel is planned in the upstream of Shihmen reservoir. Finally, turbid flow in tunnel channel is bypassed and diverted its flow down to downstream.

• Journal of Environmental Science International
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• v.13 no.12
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• pp.1089-1102
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• 2004

Seasonal variation of biogeochemical characteristics was determined in Lake Shihwa from October 2002 to August 2003. When the lake was artificially constructed for the freshwater reservoir in 1988, the development of the strong haline density stratification resulted in two-layered system in water column and hypoxic/anoxic environment prevailed in the bottom layer due to oxidation of accumulated organic matters in the lake. Recently, seawater flux to the lake through the sluice has been increased to improve water quality in the lake since 2000, but seasonal stratification and hypoxic bottom layer of the lake still developed in the summer due to the nature of artificially enclosed lake system. As the lake is still receiving tremendous amount of organic matters and other pollutants from neighboring streams during the rainy summer season, limited seawater flux sluicing into the lake may not be enough for the physical and biogeochemical mass balance especially in the summer. The excess of accumulated organic matters in the bottom layer apparently exhausted dissolved oxygen and affected biogeochemical distributions and processes of organic and inorganic compounds in the stratified two-layered environment in the summer. During the summer, ammonia and dissolved organic carbon remarkably increased in the bottom layer due to the hypoxic/anoxic condition in the bottom layer. Phosphate also increased as the result of benthic flux from the bottom sediment. Meanwhile, dissolved organic carbon showed the highest value at the upstream area and decreased along the salinity gradient in the lake. In addition to the sources from the upstream, autochthonous origin of particulate organic carbon from algal bloom in the lake might be more important for sustaining aggravated water quality and development of deteriorated bottom environment in the summer. The removal of trace metals could be attributed to scavenging by strong insoluble metal-sulfide compounds in the hypoxic/anoxic bottom layer in the summer.