• 대한토목학회논문집
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• 제31권6B호
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• pp.499-505
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• 2011

저수지내에서의 탁수층의 혼합거동은 연중 온도변화에 영향을 받으며, 특히 여름철에 발생하는 한 개 내지 두 개의 수온약층과 이에 따라 밀도가 다른 연직층 분포에 의해 변화한다. 이와 같은 밀도성층은 연직방향의 혼합을 제한하고 저수지내에서 다양한 수리학적인 거동을 야기한다. 따라서 저수지내에서는 특정 수질 문제를 해결하기 위해 선택취수를 수행할 수 있다. 본 연구에서는 이와 같은 선택취수의 효울을 해석하기 위하여 성층흐름의 수리학적 특성에 관한 실험연구를 수행하였다. two-tank 기법을 이용한 성층수조에서 밀도경사와 유량을 변수로 한 각 조건별 취수구 주변의 수리학적 특성을 입자영상유속계(PIV)를 이용하여 측정하였다. 측정된 유속장을 이용하여 Richardson 수에 따른 선택취수의 효율에 대한 상관관계를 제시하였다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회(1)
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• pp.400-401
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• 2005

• 한국물환경학회지
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• 제25권6호
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• pp.922-934
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• 2009

The transport of contaminants and spatial variation in a deep reservoir are certainly governed by the thermal structure of the reservoir. There has been continuous efforts to utilize three-dimensional (3D) hydrodynamic and water quality models for supporting reservoir management, but the efforts to validate the models performance using extensive field data were rare. The study was aimed to evaluate a 3D hydrodynamic model, ELCOM, in Daecheong Reservoir for simulating heat fluxes and stratification processes under hydrological years of 2001, 2006, 2008, and to assess the impact of internal wave on the reservoir mixing. The model showed satisfactory performance in simulating the water temperature profiles: the absolute mean errors at R3 (Hoenam) and R4 (Dam) sites were in the range of $1.38{\sim}1.682^{\circ}C$. The evaporative and sensible heat losses through the reservoir surface were maximum during August and January, respectively. The net heat flux ($H_n$) was positive from February to September, while the stratification formed from May and continued until September. Instant vertical mixing was observed in the reservoir during strong wind events at R4, and the model reasonably reproduced the mixing events. A digital low-pass filter and zero crossing method was used to evaluate the potential impact of wind-driven internal wave on the reservoir mixing. The results indicated that most of the wind events occurred in 2001, 2006, 2008 were not enough to develop persistent internal wave and effective mixing in the reservoir. ELCOM is a suitable 3D model for supporting water quality management of the deep and stratified reservoirs.

• 한국물환경학회지
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• 제24권5호
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• pp.581-591
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• 2008

Most of our rivers are fragmented by the presence of at least one large dam. Dams are often the most substantial controller of the flow regimes and aquatic environments of natural river system. The quality of downstream water released from a stratified reservoir is highly dependent on upstream reservoir water quality. Thus, an integrated modeling approach is more efficient, compared to fragmented modeling approach, and necessary to better interpret the impact of dam operation on the down stream water quality. The objectives of this study were to develop an integrated reservoir-river modeling system for Daecheong Reservoir and its downstream using a two-dimensional laterally averaged hydrodynamic and water quality model, and evaluate the model's performance against field measurement data. The integrated model was calibrated and verified using filed data obtained in 2004 and 2006. The model showed satisfactory performance in predicting temporal variations of water stage, temperature, and suspended solid concentration. In addition, the reservoir-river model showed efficient computation time as it took only 3 hours for one year simulation using personal computer (1.88 Ghz, 1.00 GB RAM). The suggested modeling system can be effectively used for assisting integrated management of reservoir and river water quality.

• 한국물환경학회지
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• 제30권5호
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• pp.491-502
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• 2014

As meteorology is the driving force for lake thermodynamics and mixing processes, the effects of climate change on the physical limnology and associated ecosystem are emerging issues. The potential impacts of climate change on the physical features of a reservoir include the heat budget and thermodynamic balance across the air-water interface, formation and stability of the thermal stratification, and the timing of turn over. In addition, the changed physical processes may result in alteration of materials and energy flow because the biogeochemical processes of a stratified waterbody is strongly associated with the thermal stability. In this study, a novel modeling framework that consists of an artificial neural network (ANN), a watershed model (SWAT), a reservoir operation model(HEC-ResSim) and a hydrodynamic and water quality model (CE-QUAL-W2) is developed for projecting the effects of climate change on the reservoir water temperature and thermal stability. The results showed that increasing air temperature will cause higher epilimnion temperatures, earlier and more persistent thermal stratification, and increased thermal stability in the future. The Schmidt stability index used to evaluate the stratification strength showed tendency to increase, implying that the climate change may have considerable impacts on the water quality and ecosystem through changing the vertical mixing characteristics of the reservoir.

• 대한토목학회논문집
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• 제32권2B호
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• pp.113-121
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• 2012

유역에서 집중호우가 발생하였을 경우 저수지 내로 고탁수층이 유입된다. 본 연구에서는 성층저수지로 유입된 고탁수층에 대한 선택취수 탁수배제 능력을 검토하기 위하여 3차원적인 접근흐름에 대한 현장실험 및 수치해석 연구를 수행하였다. 다항목수질모니터링시스템(YSI6600EDS)과 초음파유속계(YSI6600ADV)을 이용하여 선택취수시의 온도, 탁도 및 유속분포를 측정하였다. 3차원 모형인 FLOW-3D를 이용하여 저수지 내 취수탑 주변에서 유동형태를 예측하였으며, 현장실험에서의 유속 측정값과 비교분석한 결과 연직유속분포를 잘 모의함을 확인할 수 있었다. 또한 관측 자료들을 분석한 결과에 의하면 표면 취수에 비해 저층 선택취수를 수행하는 것이 고탁수층에 대한 저수지내 탁도 배제능력이 46% 증가하는 것으로 나타났다. 3차원 수치모의 해석결과, 표면취수에 비하여 중층취수를 하는 경우에는 저수지내 탁도 배제능력이 10% 증가하였고, 저층취수를 하는 경우에는 30% 증가하였다. 따라서 저수지 내 고탁수를 배제하기 위해서는 중층 또는 저층의 선택취수를 수행하는 것이 탁수배제 능력 면에서 우수한 것으로 분석되었다. 또한 수치효율이 매우 높은 1차원 SELECT 모형에서도 유사한 결과를 보여 주었다.

• 한국물환경학회지
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• 제36권5호
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• pp.392-404
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• 2020

The focus of this study was to quantify the thermal stratification and analyze the relationship between the stratification structure and the tributaries to understand flow variations in the Paldang Reservoir. The vertical distribution of the temperature and density gradients, and the depth and thickness of the thermocline were quantitatively calculated using a lake physics tool (rLakeAnalyzer) and high-frequency monitoring data. Based on a density gradient of 0.2 kg/㎥/m, the thermocline was formed from mid-May to early-September 2019 and the other periods were weakly stratified or mixed. The thickness of the thermocline was developed until 4.7 m and the depth of the thermocline was formed at a depth of 3 - 6 m at the front of the Paldang Reservoir. During the formation of the thermocline, the Namhangang and Gyeongancheon tributaries with relatively high water temperature (low-density) flowed into the upper layer of the reservoir, and the Bukhangang tributary with low water temperature (high-density) mainly affected the lower layer of the reservoir. This is because the density currents were formed due to the difference in the water temperature of the tributaries. The findings of this study may be used for constructing high-frequency monitoring and quantitative data analyses of reservoirs.

• 상하수도학회지
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• 제18권4호
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• pp.445-452
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• 2004

Intermittent deep draw artificial circulation system is one of the most widely used destratification systems to control algal bloom in reservoirs in Korea. However, there have been neither theoretical background of design criteria nor operation guide line for efficient application of the system available for such systems. A design method was developed to calculate required compressor capacity and number of circulation units considering physical interactions between stratified water layers and plumes induced by the intermittent deep draw artificial circulation system. The program was tested with data observed in Yeoncho Lake. The results indicated that the developed method can applied in the fields successfully. Further validation processes would improve design and operation methods.

• 한국물환경학회지
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• 제22권5호
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• pp.933-942
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• 2006

In this study, temperature, turbidity, suspended paniculate matter (SPM) distribution and mineral characteristics were investigated to explain spatial distribution of the turbid-water environment of Yongdam reservoir in July, 2005. Six stations were selected along a longitudinal axis of the reservoir and sampling was conducted in four depths of each station. Water temperature was showed the typical stratified structure by the effects of irradiance and inflow. Content of inorganic matter in suspended particles increased with the concentration of suspended particulate matter (SPM) due to the reduction of ash-free dry matter (AFDM). Turbidity ranged from 0.6 to 95.1 NTU and the maximum turbidity value of each station sharply increased toward downstream from upstream. The high turbidity layers were located at the depth between 12~16 m. Particle size ranged from 0.435 to $482.9{\mu}m$. day and silt-sized particles corresponded 91.9~98.9% and 1.1~8.0% in total numbers of SPM, respectively. Turbidity showed high correlations with clay (r=0.763, p<0.05) and silt content (r=0.870, p<0.05).Inorganic matter content (r=0.960, p<0.01) was more correlated with turbidity than organic matter (r=0.823, p<0.05). Mineral characterization using x-ray diffraction and electron probe microanalyzer demonstrated that the major minerals contained in the SPM were kaolinite, illite, vermiculite and smectite. As results of this study, surface water discharge as well as small size of the SPM were suggested as long-term interfering factors in settling down the turbid water in the reservoir.

• 한국물환경학회지
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• 제18권3호
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• pp.261-270
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• 2002

The artificial aeration in the middle and the small scale reservoirs is widely used to destroy the stratified layer and algal boom. This study has been conducted at the Youncho reservoir located in Keoje island since Jan. 2000 to suggest the most suitable control strategy of the artificial aeration and reduce the side effect. The main results obtained from this research are as follows. The starting time of aeration for destratification was adjusted from the end of March to the beginning of April when the natural stratification is started. In order to prevent an anoxic condition the artificial mixing should be started by the middle of April when the DO in hypolimnion is dropped to less than $5mg/{\ell}$. The decrease DO, caused by the increase in water temperature, spreads rapidly from hypolimnion to themocline. Thermal stratification disappeared after the onset of artificial aeration within 7 days in the Yuncho reservoir. The air diffusers decrease water temperature in the layer of epilimnion and thermocline, but rise it in hypolimnion. The continuous operation of air diffuser prevent the stratification and anoxic condition in hypolimnion despite of the rising of water temperature and algal abundance. The algal abundance is not observed in effective zone by aeration. The turbidity rising problem induced from the aeration is avoided by keeping an air diffuser about 1.5m high from the bottom of lake. During the summer season, ceasing the aeration should be decided carefully. And also, it is necessary to operate the system it considering weather and temperature, and depending on the number and the position of aerators.