• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1418-1423
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• 2008

연안이나 하천 등에서 공사 시 준설작업으로 인해 많은 양의 부유토사가 발생되며 발생된 부유 토사의 이송 확산은 수환경에 변화를 초래한다. 따라서 준설작업에 있어 부유토사물의 이송 확산 범위를 사전에 예측하고 대비책을 세우는 것이 중요하다. 부유토사는 준설작업 시 Cutter Head가 해저면에 닿는 순간부터 작동을 멈출 때까지 계속하여 발생하며, 이러한 과정들이 반복되면서 많은 양의 토사가 발생한다. 이렇게 발생한 부유토사는 수체흐름에 따라 움직이는데 조류가 있는 연안에서는 시간에 따라 흐름이 달라지게 된다. 본 연구에서는 2차원 수치모형인 RMA2, RMA4를 이용하여 부유토사의 확산과정을 모의하고 준설현장에서 부유토사흐름을 실측하여 비교하였다.

• Journal of the Korean Society for Marine Environment & Energy
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• v.6 no.2
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• pp.46-53
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• 2003

In order to analyze the movement characteristics of suspended solid(SS) in harbor construction, we investigate the generation and movement processes of the SS for the landfill construction by direct casting method and the grab dredging construction which is the most frequent process in harbor construction. We find that the SS is generated into a very high concentration right after the direct casting of landfill soil and continued up to 60 minutes in the landfill construction using the direct casting method with dredged materials by a ship of 700-tonnage. In the grab dredging construction, the SS is generated in a high density of concentration near at its source regardless of water depth, formed belt and diffused up to 700m along the trajectory of tidal current. Based on the result of the present study, it is recommended for the mitigation of SS generation that the silt protector be deployed near at construction site close enough to block the diffusion of SS and the body length of silt protector be long enough to mitigate the SS diffusion in the bottom layer.

• Journal of the Korean Society of Marine Environment & Safety
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• v.14 no.3
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• pp.183-187
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• 2008

Elevated concentrations of suspended solids in the marine enrironment caused by coastal developments have threatened to the marine ecosystem. Effects of suspended solids on the mortality and the modifications of glycogen levels of abalone, Haliotis discus hannai were studied. Abalone were exposed to suspended solids with concentrations of 0 (control), 1,000, 1,500 and 2,000 mg/ L for 96h. These suspended solids had no effect on the mortality of abalone. Significant decreases in the glycogen content of soft tissues were observed over 1,500 mg/ L concentration of suspended solids. These results suggested that abalone could tolerate a high level of suspended solids. However, it is necessary to observe further the long term effects of suspended solids on the physiological responses of abalone.

• Journal of the Korean Society for Marine Environment & Energy
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• v.6 no.2
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• pp.38-45
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• 2003

This paper intends to analyze the movement characteristics of the suspended solid(SS) generated in a riprap work which is the most widespread process in harbor construction. The generation and movement behaviors of SS are investigated when 1) basic ripraps (0.001~0.03㎥) are cast for breakwater construction, 2) ripraps are loaded on carrier for riprap casting in the sea-wall construction of dredged material pocket, and 3) ripraps for inner filling are cast. The result of the present study shows that the SS generation is considerable when basic ripraps are cast for breakwater construction and the SS diffusion reaches up to 500m in high tide period. When ripraps are loaded on carrier, the SS is generated by the ripraps running down into sea from carrier, thereby showing a high concentration of SS in the vicinity of carrier. In the surface layer, SS distribution is confined in the vicinity of the carrier due to the prompt sinking of the SS. However the SS in the bottom layer is diffused approximately up to loom and then the SS concentration reaches to the background one. In the riprap (less than 0.03㎥) casting for inner filling using pork crane, SS is diffused approximately up to 300m in the surface layer and more than 300m in the bottom layer. It is quite interesting that the movement of the SS generated in harbor construction is mainly controlled by wind drift in the surface layer and tidal current in the bottom layer, and also the diffusion range of SS in the bottom layer is much larger than that in the surface layer.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2003.08a
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• pp.185-193
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• 2003

준설, 매립 등의 해상공사가 해양환경에 영향을 미치는 주 요인은 공사중 발생하는 부유토사이다. 이러한 부유토사는 주변 해역으로 확산되어 여러 방식으로 해양생태계에 피해를 유발할 수 있으며, 발생 가능한 피해의 범위와 정도는 부유토사 발생율과 해저 죄적물 입도분포 및 주변 유속에 따라 결정된다. (중략)

• Korean Journal of Environment and Ecology
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• v.38 no.2
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• pp.178-188
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• 2024

The dynamics of suspended sediment (SS) in forested catchments vary depending upon human or natural disturbances, including land use change, forestry activity, forest fires, and landslides. Understanding the dynamics of SS originating from the potential sources within a forested catchment is crucial for establishing an effective water quality management strategy. Therefore, to suggest a systematic method for interpreting SS dynamics, we evaluated the performance and applicability of ten methods for calculating the hysteresis index based on observed hydrological data and two calculation models (Lawler's method and Lloyd's method) with five sampling intervals (50th, 25th, 10th, 5th, and 1st percentiles). Our results showed that Lloyd's method, which used a sampling interval at the 1st percentile, had the largest number of analyzable runoff events and exhibited the best performance. The results of this study can contribute to quantifying the hysteresis in the relationship between discharge and SS and provide useful information for interpreting SS dynamics.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.435-438
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• 2008

본 연구에서는 최근 집중호우로 인해 탁수문제가 심각한 소양강 유역의 효과적인 탁수 관리를 위한 SWAT 모형 구축 및 유역의 시공간 토사유실 분석을 실시하였다. 검보정된 SWAT 모형을 이용하여 소유역별 부유사 발생량을 분석한 결과 조항천, 영실천/북천 상류, 인북천 상류 유역(서쪽) 등에서 연간 10톤/ha이 상의 부유사가 발생하여 소양강댐 유역에서의 탁수유발에 직접적인 영향을 미치는 것으로 나타났으며, 어론천, 자운천 등은 연간 6톤/ha이상의 부유사 발생이 예측되었다. 특히 내린천의 최상류 두 유역인 조항천과 주운천 유역에서 발생하는 부유사는 소양강 전체 유역에서 발생하는 부유사의 13.6%를 차지하는 것으로 나타나 이 유역들에 대한 토사유실 저감대책이 필요하다고 판단된다. 한편 유역에서 발생하는 부유사량의 시간별 특성을 알아보기 위하여 댐 유입부에 유입되는 부유사량의 분포를 분석한 결과, 최근 6년간 발생한 부유사량을 연도별로 살펴보면 2003년에 최고 약 1,200,000톤이 댐으로 유입되는 것으로 나타났으며, 2005년도에 최저 40,000톤이 유입된 것으로 분석되었다. 본 연구결과는 향후 각 소유역별로 탁수를 유발하는 토사 유실량 평가, 유역의 토사유실 저감대책 효과분석 및 저수지 모형과의 연계를 통한 유입된 탁수의 효율적인 관리 대책 수립에 이용될 것이다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.1
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• pp.66-70
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• 2003

Harbor construction works such as dredging, reclamation, riprap dumping and so on generate suspended sediment to affect ocean environment negatively so silt protector is widely used to keep construction site from deteriorating at the moment. This study has a purpose to improve our design techniques by comparing the design procedures of the silt protector between Korea and Japan.

• Journal of Forest and Environmental Science
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• v.10 no.1
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• pp.57-65
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• 1994

This study was carried out to clarify the sediment export by measuring suspended solids included in streamflow during the rainy season. The study area is located in Experimental Forests, Kangwon National University, where the forest road is under construction. For this purpose, the forest watershed with construction of forest road was compared with normal forest watershed in amount of rainfall and discharge, suspended solids and discharge, and the amount of rainfall and suspended solids. The results were shown as followings. 1. The relationship of discharge and the amount of rainfall was shown as Table 3 and Fig. 3. The delay time of peak point observed in hydrograph was changed by rainfall intensity and amount of previous rainfall. That is, when there was a rain on 12. Jun(more than 20mm/hour for hours), the peak point began three hours after the rainfall intensity over 20mm/hour, and showed $1514m^3/hour$ in automatic water level recorder. In case of the 8th of Aug.(maximum rainfall intensity: 40mm/hour), the peak point of discharge was $1246m^3/hour$ in the same time with maximum rainfall intensity. And on the 20th of Aug.(the maximum rainfall intensity: 17.2mm/hour), the peak point of discharge was $1245m^3/hour$ two hours after the maximum rainfall intensity. 2. On watershed under forest road construction, the relationship between discharge and suspended solids is that suspended solids was proportionately increased by raising discharge. That is, on the 12th of Jun, the maximum of discharge per hour was $1514m^3/hour$ and 1261mg/l of suspended solids was observed an hour after peak point of discharge. And in case of 8th and 20th Aug., each of peak points is $1246m^3/hour$ and $1245m^3/hour$ by measuring time. The maximums of suspended solids measured within two watersheds were examined in value of 4952mg/l and 472mg/l at the same time. 3. During the rainy season, the concentration of suspended solids was influenced by rainfall intensity and indicated especially curve-regressional increase in case of strong rainfall intensity. In each of watersheds, the maximums of suspended solids were 1261mg/l and 125mg/l, 4952mg/l and 44mg/l, and 472mg/l and 4mg/l by the order of rain(a), (b), and (c). Two watersheds showed a remarkable difference.

• Journal of Korean Society of Forest Science
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• v.85 no.2
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• pp.280-287
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• 1996

This study was carried out to investigate the export rate of suspended sediment by different precipitation intensity after forest road construction for torrential streams on three different watersheds with various forest road density(Watershed A : 6.67m/ha, Watershed B : 5.52m/ha, and Watershed C : control) in the Experimental Forest of Kangwon National University. The results were as follows. 1. Closely related to the the amount of rainfall in both 1994 and 1995, the average streanfkiw rate was less than $0.25{\times}10^4m^3/day$ during May and June and $5.0{\times}10^4m^3/day$ during July and August. More than $25{\times}10^4m^3/day$ of streanflow rate was occurred twice in 1994 and seven times in 1995. 2. The amount of suspended sediment in three watersheds was less than standard of drinking water(25mg/l) before road construction with daily rainfall of 74mm, 92mm, and 120mm in 1994, also after road construction with daily rainfall of 21mm and 47mm in 1995. But, under the 192mm of daily rainfall, Watershed C did not show the difference in the amount of suspended sediment, however, Watershed A and B produced 1,525mg/l and 775mg/l, respectively, which is 61 and 31 fold of stabdard of drinking water, and construction to export for 35 hours after rainfall. 3. The maximum amount of suspended sediment was less than the standard of drinking water with light rainfall before and after road construction. Under the 192mm of daily rainfall, the maximum amounts of suspended sediment in Watershed A and B were 13,150mg/l and 2,690mg/l, of 526 and 108 fold of standard of drinking water, respectively, showing obvious water pollution by sedimentation. Results of the study indicated that the forest road construction had great influence on the sedimentation, and getting increased by higher road density and heavier rainfall. Therefore such practices as vegetation covering and soil erosion control facility should be established accompanying with forest road construction to prevent from sedimentation.