• Title/Summary/Keyword: Daechung reservoir

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Effect of Cultivation Activity in Daecheong Lake Flood Control Site on Water Quality (대청호 홍수조절지 내 경작활동이 수질에 미치는 영향)

  • Choi, Hyeseon;Jeon, Minsu;Kim, Leehyung
    • Journal of Wetlands Research
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    • v.22 no.1
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    • pp.49-58
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    • 2020
  • The excessive use of fertilizer and compost in agricultural land increases the accumulation of nutrients in soil. The surplus nutrients in soil transported through surface and sub-surface flow can lead to water pollution problems and algal bloom. Moreover, nutrient accumulation and continuous crop cultivation changes the physical structure of the soil, which increases the potential of nutrient. The cultivation in the Daecheong Lake reservoir area may have a direct effect on the lake's water quality due to leaching and releasing of nutrients when water level rises. This research was carried out to analyze the physical and chemical properties of soil in the agricultural areas surrounding Daecheong Dam reservoir to provide basic data available for the establishment of Daecheong Lake water quality management measures. The soil of the Daecheong Lake reservoir was classified as sandy Loam, where surplus nutrients can be transported. Chemical compositions in the soil were found to be significantly affected by use of different fertilizer amounts. Nutrient outflow occurred during spring rainfall events from the rice paddy fields, whereas excess nutrients from summer to fall seasons originated from dry paddy fields. Nutrient outflow from dry paddy fields is mainly from sub-surface flow. Organic agricultural wastes from agricultural land and excessive vegetation inside the river was also evaluated to contribute to the increase in organic matter and nutrients of the river. The results can be used to select the priority management area designation and management techniques in the Daecheong Lake for water quality improvement.

Storage Reallocation for Daechung Multipurpose Reservoir (대청댐 용량 재할당에 대한 연구)

  • Yi, Jae-Eung;Kwon, Dong-Seok
    • Proceedings of the Korea Water Resources Association Conference
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    • 2005.05b
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    • pp.304-308
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    • 2005
  • 본 연구에서는 금강유역의 대청다목적댐을 대상으로 대청댐의 제한수위를 변화시켜 가며 대청댐의 홍수조절과 용수공급능력을 판단하였다. 이를 위하여 홍수기 저수지 모의운영 방법 중 Rigid ROM 기법을 수정$\cdot$보완하여 개발한 모의기법을 이용하여 빈도별 홍수유입량에 대해 홍수기 저수지 운영을 실시하였다. 모의운영에 의해 얻은 방류량을 대청댐으로부터 공주지점까지 홍수추적함으로써 공주지점의 최대홍수량을 산정하였다. 산출된 공주지점 최대홍수량을 토대로 대청댐 제한수위의 변화와 빈도별 유입 홍수량의 함수로써 공주지점의 최대홍수량 관계식을 유도하고, 이 관계식을 이용하여 합리적인 대청댐 재할당 수위 및 대청댐 홍수조절 능력을 산정하였다. 또한 대청댐의 상시만수위를 변화시키면서 신뢰도 $95\%$를 만족시키는 용수공급량을 산정하였다. 본 연구의 결과, 홍수조절 측면에서 대청댐의 상시만수위를 78m로 재할당시에 24시간 지속기간을 갖는 300년 빈도 홍수에도 홍수조절이 가능하므로 대청댐의 용량 재할당량은 78m가 적합한 것으로 판단된다. 78m로 재할당 했을 시 이수측면에서 신뢰도 $95\%$를 만족시키는 용수공급량은 기존의 상시만수위 76.5m로 운영했을 시와 비교하여 약 $3\% 증가하는 효과를 얻을 수 있었다.

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Microcystin Production by Microcystis sp. under N or P Limitation

  • Oh Hee-Mock;Kim Jee-Hwan
    • Proceedings of the Microbiological Society of Korea Conference
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    • 2001.11a
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    • pp.113-120
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    • 2001
  • The production of microcystins from Microcystis aeruginosa was investigated in a P-limited continuous culture and a batch culture. The microcystin content of M aeruginosa was higher at a lower $\mu$, whereas the microcystin (MC)-producing rate was linearly proportional to $\mu$. The ratios of the MC-producing rate to the C-fixation rate were higher at a lower $\mu$. Consequently, increases in the microcystin content per dry weight along with the production of the more toxic form, MC-LR, were both observed under more P-limited conditions. The microcystin content of M. aeruginosa exhibited a high correlation with the total N content regardless of N-fixed or P-fixed culture. The microcystin concentration was investigated from spring to autumn in 1999 in the Daechung Reservoir, Korea. The dominant species in the algal blooming season was Microcystis. When the microcystin concentration exceeded about 100 ng $1^{-1}$ the ratio of particulate to dissolved total nitrogen (TN) or total phosphorus (TP) interestingly converged at a value of 0.6. The microcystin concentration was lower than 50 ng $1^{-1}$ at a particulate N:P ratio below 8, whereas the microcystin concentration varied quite substantially from 50 ng $1^{-1}$ to 250 ng $1^{-1}$ at a particulate N:P ratio> 8.

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Performance Analysis of Water-to-Air Heat Pump System under Water Temperature and Load Ratio (열원 및 부하조건에 따른 물-공기 히트펌프 시스템의 성능분석)

  • Cho, Yong;Lee, Dong Keun
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.05a
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    • pp.194.2-194.2
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    • 2011
  • Heating and cooling performance has been analyzed for the water-source heat pump system using raw water from Daechung reservoir. During heating operation from March to May, water temperature is not good condition for a heat source due to the higher atmospheric temperature. Avearged heating load ratio is only 14.3%, and the averaged unit COP and system COP are estimated to be 2.46 and 2.15 respectively. The COP is affected considerably by the water temperature, and the unit COP is increased from 2.16 at $5^{\circ}C$ to 2.95 at $11^{\circ}C$. Cooling performance is analyzed with the measured data from June to August. During cooling operation, raw water has lower temperature by 4. $5^{\circ}C{\sim}4.7^{\circ}C$ than the atmosphere. The load ratio is 39.2%, and the averaged unit COP and system COP are estimated to be 7.25 and 6.13 respectively. The heating COP is affected by the load ratio rather than water temperature. The COP is increased for 20%~40% load ratio, while is decreased for 40%~60% load ratio. It is estimated that the compressor operation combination for 3 (two constant speed and one inverter) compressors is changed for the load ratio.

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A Development of Multi-metric Approach for Ecological Health Assessments in Lentic Ecosystems (정수 생태계 건강성 평가를 위한 다변수 메트릭 모델 개발)

  • An, Kwang-Guk;Han, Jung-Ho
    • Korean Journal of Ecology and Environment
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    • v.40 no.1
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    • pp.72-81
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    • 2007
  • The purpose of this study was to develop a multi-metric Lentic Ecosystem Health Assessment (LEHA) model and apply model to dataset sampled from Daechung Reservoir in September 2005. The metrics were composed of 11 parameters such as physical, chemical and biological variables. The metric attributes of $M_1{\sim}M_8$ followed after the model of biological integrity using fish assemblages that previously adapted in lotic ecosystems, while the metrics of $M_9{\sim}M_{11}$ were added on the basis of literature. The metric of $M_9$ reflected habitat conditions in the littoral zone and the metric of $M_{10}$ reflected chemical conditions of the reservoir. For the application of regression analysis of long-transformed conductivity [$Log_{10}$(Cond)] against $COD_{Mn}$, based on 150 sampling sites at Korean reservoirs, showed that the variation of conductivity was explained 77.4% [$COD_{Mn}=4.42{\times}Log_{10}(Cond)-5.43;\;R^2=0.774$, p<0.01, n=150] by the variation of $COD_{Mn}$. The metric of $M_{11}$ was based on Tropic State Index (TSI), based on chlorophyll-${\alpha}$ concentrations (Chl-${\alpha}$). Analysis of TSI $(Chl-{\alpha})$ showed that above 50 was estimated "1", $40{\sim}50$ was estimated "3" and below 40% was estimated '5'. Overall, velues of LEHA in the reservoir averaged 30.5, indicating a "fair${\sim}$poor condition", which is judged by the criteria of U.S. EPA (1993). More studies such as metric numbers and attributes should be done for the application of the model.

A Novel Microcystin-degrading Bacterium, Microbacterium sp. MA21 (Microcystin을 분해하는 신균주 Microbacterium sp. MA21)

  • Ko, So-Ra;Lee, Young-Ki;Oh, Hee-Mock;Ahn, Chi-Yong
    • Korean Journal of Environmental Biology
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    • v.31 no.2
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    • pp.158-164
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    • 2013
  • A microcystin-degrading bacterium was isolated from Daechung reservoir, Korea. The isolated bacterium was identified as Microbacterium sp. by 16S rRNA gene sequence analysis, and designated as Microbacterium sp. MA21. This strain degraded cyanobacterial hepatotoxin, microcystin-LR, over 80% when incubated at $30^{\circ}C$ for 12 hr in R2A medium. Two unknown metabolites of microcystin were also identified during the degradation process. Although only Sphinogomonas and Actinobacteria have been known to degrade microcystin previously, this is the first report that Microbacterium sp. MA21 could degrade microcystin.

The Distribution of Organic Carbon and its Decomposition Rate in the Kum River, Korea (금강수계에서 수중 유기탄소의 분포와 분해속도)

  • Jang, Chang-Won;Kim, Jai-Ku;Kim, Dong-Hwan;Kim, Bomchul;Park, Ju-Hyun
    • Journal of Korean Society on Water Environment
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    • v.24 no.2
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    • pp.174-179
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    • 2008
  • The distribution of organic carbon and its decomposition rate were studied in the middle and down stream reaches of the Kum River system, Korea. Water samples were collected from May to June in 2006 at seven mainstream sites and three tributary sites from the river mouth to the Daechung Reservoir outlet. The change of DOC and POC were measured during incubation for the determination of decomposition rate. The reduction of organic carbon during 20 days' incubation was regarded as labile or biodegradable organic carbon (LDOC, LPOC), and the remaining organic carbon was regarded as recalcitrant organic carbon. The mean TOC was $5.17({\pm}1.49)mgC{\cdot}L^{-1}$ in the mainstream sites and $7.09({\pm}1.48)mgC{\cdot}L^{-1}$ in tributary sites, respectively. TOC comprised of 62% DOC and 38% POC. LPOC was approximately 68% of POC, while LDOC was only 24% of DOC. Mean decomposition rate of TOC was about $0.03day^{-1}$. Mean decomposition rates of LPOC ranged from $0.10day^{-1}$, and that of LDOC was approximately $0.08day^{-1}$. The decomposition rate of both LPOC and LDOC did not show significant difference between mainstream and tributary sites. The result of this study can give a guide to the selection of parameters in the calibration processes of water quality models.

Development of a Distributed Rainfall-Runoff System for the Guem River Basin Using an Object-oriented Hydrological Modeling System (객체지향형 수문 모델링 시스템을 이용한 금강유역 분포형 강우-유출 시스템의 개발)

  • Lee, Gi-Ha;Takara, Kaoru;Jung, Kwan-Sue;Kim, Jeong-Yup;Jeon, Ja-Hun
    • Proceedings of the Korea Water Resources Association Conference
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    • 2009.05a
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    • pp.149-153
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    • 2009
  • Physics-based distributed rainfall-runoff models are now commonly used in a variety of hydrologic applications such as to estimate flooding, water pollutant transport, sedimentation yield and so on. Moreover, it is not surprising that GIS has become an integral part of hydrologic research since this technology offers abundant information about spatial heterogeneity for both model parameters and input data that control hydrological processes. This study presents the development of a distributed rainfall-runoff prediction system for the Guem river basin ($9,835km^2$) using an Object-oriented Hydrological Modeling System (OHyMoS). We developed three types of element modules: Slope Runoff Module (SRM), Channel Routing Module (CRM), and Dam Reservoir Module (DRM) and then incorporated them systemically into a catchment modeling system under the OHyMoS. The study basin delineated by the 250m DEM (resampled from SRTM90) was divided into 14 midsize catchments and 80 sub-catchments where correspond to the WAMIS digital map. Each sub-catchment was represented by rectangular slope and channel components; water flows among these components were simulated by both SRM and CRM. In addition, outflows of two multi-purpose dams: Yongdam and Daechung dams were calculated by DRM reflecting decision makers' opinions. Therefore, the Guem river basin rainfall-runoff modeling system can provide not only each sub-catchment outflow but also dam inand outflow at one hour (or less) time step such that users can obtain comprehensive hydrological information readily for the effective and efficient flood control during a flood season.

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Masking Effect of Chlorine on Algae-related Taste and Odor in Drinking Water Supplies (염소의 상수원 내 조류 이취미 Masking 효과)

  • Kim, Young-il;Lee, Yu-Jeong;Shin, Heung-Sup;Bae, Byung-Uk
    • Journal of Korean Society of Water and Wastewater
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    • v.22 no.2
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    • pp.227-232
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    • 2008
  • The masking effect of chlorine on algae-related taste and odor(T&O) compounds has long been an important issue for water suppliers. In this study, masking experiments with chlorine were performed on two kinds of treated water and one of raw water. After adding chlorine(0 to 0.8 mg/L) to water samples, odor intensity was evaluated by a newly developed sensory method(2-out-of-5 odor test) for three days along with the measurement of residual chlorine concentration. Even though the relationship between the residual chlorine concentration and odor reported by the sensory analysts was not always coincident, it was proved that residual chlorine more than a certain concentration could completely mask both added geosmin and naturally occurring T&O compounds. For the sand-filtered water spiked with 10 ng/L of geosmin, 0.12-0.18 mg/L of residual chlorine was necessary to achieve complete masking. In the case of GAC-filtered water, 10 ng/L of spiked geosmin was completely masked by 0.15-0.1 mg/L of residual chlorine. Combined ozone and GAC was not enough to treat raw water spiked with 300 ng/L of geosmin. In this experiment, sensory analysts were able to detect earthy or musty odors from the treated water. From a masking experiment with raw water taken from the Daechung Reservoir, it was found that fishy odor was more difficult to mask with chlorine than earthy odor. As the chlorine residual declined, the analysts began to notice the original odor and the fishy odor was noticed earlier than the earthy odor.

Estimation of Suspended Solid Concentration Variation in Daechung Reservoir using Satellite Imagery (위성영상을 이용한 대청호 부유물질 농도 변화 추정)

  • Park, Jin-Ki;Park, Jong-Hwa;Na, Sang-Il;Beak, Shin-Chul
    • Proceedings of the Korea Water Resources Association Conference
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    • 2011.05a
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    • pp.203-203
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    • 2011
  • 최근 들어 기후변화에 따른 강우패턴이 바뀌고 각종 하천개발이나 토목공사, 농경지, 경작지 등의 객토 등으로 인해 매년 탁수의 발생이 크게 증가하고 있는 추세이다. 특히 여름철 집중강우의 영향에 따라 상류지역 하천에서 발생하는 부유물질은 호수로 유입되어 장기간 체류하며 심각한 오염원으로서 수중생태계에 치명적인 영향을 주고 있다. 또한 하천과 호수의 상류지역의 농경지나 경작지에서 발생된 부유물질에는 과도한 비료의 사용으로 입자표면에 많은 인을 포함하고 있어 호수 수질악화 및 부영양화의 직접적 요인이 되고 있다. 이에 따라 세계 각국에서는 부유물질은 오염원뿐 아니라 생태계에 영향을 주는 인자로서 엄격히 규제하고 있으며, 특히 농업지역이 많은 하천에 대해서는 유역전체를 대상으로 부유물질에 대한 총량관리를 적용하고 있다. 그러나 우리나라의 경우 하천 수질기준 1급수의 부유물질 농도는 25 mg/l 로서 이는 선진국과 유사한 기준이나 실질적으로 규제가 어려운 실정이다. 수환경에서의 부유물질이란 수체 내 존재하는 유기성, 무기성 물질로써 입자 지름이 2mm 이하의 물에 용해되지 않는 물질을 말하는 것으로, 물의 탁도를 유발시키는 원인이 되며 빛을 차단하여 수생태계에 악영향을 초래한다. 국내 132개 하천을 대상으로 부유물질의 농도와 어류의 종 다양성간 상관성을 조사한 결과, 부유물질의 농도가 15 ~ 20 mg/l 이상에서 종 다양도는 1.0 이하로 급감하는 경향을 보였다(최재석 등, 2004). 한편, 대청호는 1975년부터 1980년에 걸쳐 건립된 저수 면적 $72.8km^2$, 저수량 15억톤의 인공호수로 우리나라 3번째 규모의 인공호수이다. 특히, 대전 및 청주지역의 식수는 물론, 생활용수 및 공업용수를 공급하는 중요한 수자원으로서 부유물질에 대한 모니터링 및 관리가 시급하나 저수 용량이 크고 체류시간이 길어 여름철 부영양화가 매년 반복되고 있다. 따라서 본 연구에서는 부유물질의 농도 변화에 따른 분광반사 특성을 조사하고, 이를 대청호의 Landsat 위성영상에 적용하여 대청호 내 부유물질의 농도변화를 추정하였다. 이와 함께 부유물질 농도 변화에 따른 탁수 환경 모니터링에 원격탐사 기법이 효과적임을 제시하고자 하였다.

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