• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.642-642
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• 2012

최근에 들어 지구온난화에 따른 기후변화의 영향으로 국지성 집중호우와 돌발성 호우가 한반도 뿐 아니라 전 세계적으로도 많이 나타나고 있고, 그로 인한 이상홍수의 발생이 우리나라의 인명 및 재산피해를 날로 증가시키고 있는 추세이다. 그러나 현재 국내의 홍수방어시스템은 정확도 및 선행시간 확보 등의 측면에서 국민들의 요구수준까지는 그 역할을 수행하지 못하고 있는 실정이다. 또한 최근 4대강 살리기 사업을 통해 수행된 보 설치 및 하도 준설로 인해 하천환경의 변화가 크게 발생하여, 보다 정확하고 신속한 홍수위 예측기법이 요구되고 있는 실정이다. 이에 따라 현재 4대강 홍수통제소에서는 정확한 홍수위예측을 위해 4대강 본류 및 주요 지류에 대해 수리모형을 구축하고 있고, 기존의 저류함수모형에 의한 강우-유출 해석기법을 적용하여 주요 지류에 대한 유입량을 산정하기 위한 모형을 구축중에 있다. 국내 홍수방어 시스템에 현재까지 사용되어 오고 있는 저류함수모형 및 수위-유량 관계식을 이용한 방법은 물리적 기반의 홍수예측모형으로 유역의 지형학적 인자와 그에 따른 여러 변수를 포함하기 때문에 하천환경의 변화로 인해 각각의 추적과정에서 오차들이 발생하여 해석결과에 영향을 미치는 단점이 있다. 이에 반해 데이터 기반 모형은 강우-유출 모형에서 사용되는 많은 수문학적 자료 및 매개변수들의 사용 없이 오직 수위 및 강우측정 자료만을 이용하여 홍수를 예측하는 모형이다. 본 연구에서는 낙동강 유역에 대해 보다 정확한 홍수위 예측을 위해 현재 낙동강홍수통제소에서 구축중인 낙동강 본류의 수리모형의 주요 지류의 유입량 산정을 위해 기존의 물리적 기반 모형이 아닌 뉴로-퍼지(Neuro-Fuzzy) 모형을 이용한 data 기반 모형을 적용해 기존 물리적 기반 모형과 비교 분석 하고자 하였다. 낙동강의 주요지류인 감천, 금호강, 남강, 내성천, 밀양강, 반변천, 위천, 황강을 적용유역으로 선정하여 유역별로 티센망을 구축하였고, 각 지류별로 수위관측소를 선정하여 최근 10년동안 낙동강유역의 홍수예 경보가 발령되었거나 많은 비가 온 사상을 선정해 모형을 검증하였다. 모형은 실시간 수위측정 자료와 강우자료 및 해당유역 댐의 방류량 자료를 이용해 유역별 최적 입력자료 조합을 선정하여 간단하게 구축할 수 있었다. 또한 10분 단위 및 30분 단위의 입출력 자료로 모형을 구축하여 비교하였다. 이번 연구에서 수행한 낙동강유역에서의 뉴로-퍼지(Neuro-Fuzzy) 모형을 이용한 홍수예측기법을 통해 몇가지 data만으로 유역의 주요지점에 대한 홍수위와 홍수량을 예측할 수 있음을 확인할 수 있었다. 모의 결과는 실측치와 비교해 정확도 면에서 우수함을 보여 주었으나 예측시간이 길어질수록 실측치의 경향을 벗어나는 결과를 보였다. 그러나 실시간 홍수예 경보에 있어서는 만족할만한 선행시간을 확보할 수 있었다. 구축된 Data 기반 모형이 물리적 기반 모형과 더불어 낙동강 홍수예 경보를 위한 모형으로 사용될 수 있다면 보다 효율적인 예 경보 체계 구축에 도움을 줄 수 있을 것으로 판단된다.

• Journal of Korea Water Resources Association
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• v.51 no.1
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• pp.61-70
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• 2018

This study examined how to determine the optimal sediment level in dam reservoir for efficient plan and operation of dam. Currently, Korea is applying a horizontally accumulated method for sediment level estimation for the safety design of dam and so the method estimated relatively higher level than others. However, the sediment level of dam reservoir should be accurately estimated because it is an important factor in assessing life cycle of a dam. The sediment level in dam reservoir can be determined by SED-2D model linked with RMA-2, horizontally accumulated method, area increment method, and empirical area reduction method. The estimated sediment level from each method was compared with the observed sediment level measured in 2007 in Imha dam reservoir, Korea and then the optimal method was determined. Also, the future sediment level was predicted by each method for the future trend analysis of sediment level. As the results, the most accurate sediment level was estimated by the empirical area reduction method and the future trend of sediment level variation followed the past trend. Therefore, we have found that the empirical area reduction method is a proper one for more accurate estimation of sediment level and it can be validated by the results from a numerical model of SED-2D linked with RMA-2 model.

• Journal of Korea Water Resources Association
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• v.50 no.11
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• pp.769-779
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• 2017

As the occurrence of drought is recently on the rise, the reliable drought forecasting is required for developing the drought mitigation and proactive management of water resources. This study developed a probabilistic hydrological drought forecasting method using the Bayesian Networks and drought propagation relationship to estimate future drought with the forecast uncertainty, named as the Propagated Bayesian Networks Drought Forecasting (PBNDF) model. The proposed PBNDF model was composed with 4 nodes of past, current, multi-model ensemble (MME) forecasted information and the drought propagation relationship. Using Palmer Hydrological Drought Index (PHDI), the PBNDF model was applied to forecast the hydrological drought condition at 10 gauging stations in Nakdong River basin. The receiver operating characteristics (ROC) curve analysis was applied to measure the forecast skill of the forecast mean values. The root mean squared error (RMSE) and skill score (SS) were employed to compare the forecast performance with previously developed forecast models (persistence forecast, Bayesian network drought forecast). We found that the forecast skill of PBNDF model showed better performance with low RMSE and high SS of 0.1~0.15. The overall results mean the PBNDF model had good potential in probabilistic drought forecasting.

• Journal of Korea Water Resources Association
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• v.39 no.3 s.164
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• pp.241-252
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• 2006

Numerical models for seepage analysis are useful tools to analyze problems and design protection techniques that are related to seepage through a levee. Though every model may have its own limitations and shortcomings, there were no generalized verifications or calibrations for the commercial models. It means that users can run the model and get the result without understanding nor taking any enough training. This paper Investigates applicability and suitability of some seepage numerical models by comparing analytical solutions with experiments in the user's viewpoint. The results showed that it is more desirable to use analyses with unsaturated-unsteady condition rather than those with saturated-steady conditions, since seepage phenomenon of real levees are changed according to water level and soil property. This study also compared the calculated unsteady solutions with the calculated steady solutions for the levee at Koa of the Nakdong River The comparison revealed that as the result, the safety factor of $2.0{\sim}3.5$ has the same effects for seepage protection techniques when they are designed on the basis of steady-state analysis.

• Tunnel and Underground Space
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• v.22 no.4
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• pp.227-242
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• 2012

Youngju multipurpose dam is planned to minimizing the damage by flood and obtaining the water for industrial use in Nakdong river region. Faults in rock mass have strong influences on the behaviors of dam structure. Thus, it is very important to analyse for the characteristics of fault rocks in dam design. However, due to the limitation of geotechnical investigation in design stages, engineers have to carry out the additional geological survey including directional boring to find the distribution of faults and the engineering properties of faults for stability of dam. Especially, the selection of location of dam and type of dam considering fault zone must be analyzed through various experimental and numerical analysis. In this study, various geological survey and field tests were carried out to analyse the characteristics of the large fault zone through the complex dam is designed in foundation region. Also, the distribution of structural geology, the shape of faults and the mechanical properties of fault rock were studied for the reasonable design of the location and type of dam for long-term stability of the complex dam.

• Journal of Preventive Medicine and Public Health
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• v.26 no.2 s.42
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• pp.202-209
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• 1993

A accidental spills of phenol(100%) to the river Nakdong with subsequent contamination of the tap water fer about two million consumers in Taegu city of Korea were occurred in March 1991. A historical cohort study of 6,913 individuals was undertaken to determine the associated with illness. Population subjects were divided into two groups of exposed and unexposed. Exposed subjects were reported to be phenol associated symptoms significantly higher than those in a nearby unexposed area(39.6% vs 9.4%, p<0.01). Especially, in the related symptoms, highly significant differences were noted in the number of subjects reporting gastrointestinal illness such as nausea, vomiting, diarrhea, or abdominal pain. During the accident, study subjects who experienced peculiar taste or odor in the tap water were significantly higher in the exposed areas(92% vs 34.3%). Chlorophenols formed from chlorination of water may have aggravated the problem.

• Korean Journal of Ecology and Environment
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• v.35 no.4 s.100
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• pp.249-256
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• 2002

The variation of trophic state was measured in a reservoir (Lake Andong, Korea) from 1993 to 2000. Phosphorus loading from the watershed was estimated by measuring total phosphorus concentration in the main inflowing stream (the Nakdong River). Phosphorus discharge from the pen-type fish farms was estimated from the amount of fish feed and the rate of phosphorus excretion per feed weight. The transparency in summer was about 2.0 m in 1993 and 1994, but it decreased to about 1.2 m in 1997 and 1998, and recovered to about 2.3 m in 1999 and 2000. TP increased from $11-30\;mgP/m^3$ in 1993 to $18-42\;mgP/m^3$ in 1998, but recovered to $8-13\;mgP/m^3$ in 2000, whereas TN decreased slightly from 1.81-2.96 mgN/L in 1993 to 1.17-1.80 mgN/L in 2000. TN/TP ratios decreased from 82-281 in 1993 to 21-143 in 1998, but again increased to 101-209 in 2000 due to the decrease of TP. The average chlorophyll-a concentration in growing season was in the range of $4.8-16.2\;mg/m^3$ from 1993 to 1997, but it decreased to $3.7-5.2\;mg/m^3$ after 1998. Trophic State Index had shown a gradual increase until 1996, and since then it has declined. The major cause of the trophic state recovery is thought to be the removal of fish farms in April 1998.

• Korean Journal of Ecology and Environment
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• v.49 no.4
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• pp.308-319
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• 2016

In order to evaluate the role of macrophytes as refuge of zooplankton on physical distribution (i.e. summer rainfall), we investigated the environmental factors, macrophytes, and zooplankton in waterside zones (macrophytes zones) and open water zones of 17 wetlands from May and August, 2011. In this study, a total of 51 zooplankton species were identified, and Polyarthra sp. and Diaphanosoma brachyurum were found to be the most dominant species. Waterside area of each wetland were occupied by a total of 10 macrophyte species, species composition and biomass (dry weight) were different in the survey sites. Zooplankton was more abundant in waterside zone than open water zones lacking macrophytes (One-way ANOVA, df=2, F=27.1, P<0.05), in particular, waterside zone of 1, 8, 9, 10, and 11 wetland were supported by high zooplankton density after summer rainfall. This wetlands were developed by various macrophyte species than other wetland, and submerged plant commonly presented. Waterside zones with various macrophyte species provides complexity to the habitat structure, should be utilized as refuge to avoid disturbance such as summer rainfall. The results indicate that macrophytes are the key components to enhance bio-diversity include zooplankton, and the inclusion of diverse plant species in wetland construction or restoration schemes will result in ecologically healthy food webs.

• Journal of fish pathology
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• v.13 no.2
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• pp.137-142
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• 2000

Differences in larvicidal activity of complement and chemiluminescent response of phagocytes in carp (Cyprinus carpio), crucian carp (Carassius auratus) and false dace (Pseudorasbora parva) against excysted metacercariae of Clonorchis sinensis were investigated. The prevalence of C. sinensis metacercariae of false daces caught at Nakdong river (NR) was 100%. However, no C. sinensis metacercariae were found in false daces, which were collected at a reservoir in Chinyoung (CY), crucian carps and carps. The sera of false dace, which were intensively infected with C. sinensis metacercariae, killed excysted metacercariae of C. sinensis more readily than that of carp. However, the serum obtained from C. sinensis metacercariae-free false dace showed the lowest larvicidal ability. The larvicidal ability of sera collected from each fish species completely disappeared when the complement was inactivated by heating. When supernatant of excysted metacercariae homogenate were added to phagocytes of each species, the chemiluminescent responses were significantly (p<0.05) diminished in false dace and carp. The inhibition ratio of chemiluminescent responses by the supernatant was 22.9% in false dace, 9.6% in crucian carp and 12.4% in carp.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.488-488
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• 2018

본 연구는 보 구간에서 조류와 조류 발생원인 물질의 거동해석 및 조류예측모델의 입력 자료로 활용하기 위하여 부유물질의 침강량과 침강속도를 조사하였다. 낙동강 수계 4개보(달성보, 강정고령보, 합천창녕보, 창녕함안보)를 대상으로 2017년 6월, 7월, 11월, 12월에 조사하였으며, Sediment trap을 이용하여 포집한 침강물질에 대해 seston, POC, PON, POP, Chl-a, Pheo-a의 침강량, 침강속도 및 물질의 함량비를 분석하였다. 조사기간 동안 낙동강수계 4개보 지점에서 seston, POC, PON, POP, Chl-a, Pheo-a 의 침강량은 각각 $322.7{\sim}58,011.5mg/m^2/day$, $33.8{\sim}1,127.2mg/m^2/day$, $4.2{\sim}150.6mg/m^2/day$, $0.667{\sim}10.634mg/m^2/day$, $0.3{\sim}18.7mg/m^2/day$, $0.3{\sim}14.7mg/m^2/day$의 범위로 나타났으며, seston, POC, PN, PP, Chl-a의 침강속도는 각각 0.02~1.46m/day, 0.02~1.36m/day, 0.03~3.18m/day, 0.01~1.18m/day, 0.02~0.60 m/day의 범위로 나타났다. 조사기간 동안 4개보 지점의 평균 침강속도는 seston 0.94m/day, POC 0.44m/day, PON 0.52m/day, POP 0.21m/day, Chl-a 0.22m/day로 보 건설 전인 2004년도 낙동강 본류 지점에서의 침강속도(seston 14.54 m/day, POC 18.32m/day, PON 1.64m/day, POP 5.96m/day, Chl-a 0.29m/day)에 비해 적은 것으로 나타났다. 한편 활성을 잃은 식물플랑크톤을 나타내는 Pheo-a의 농도와 살아있는 식물플랑크톤의 현존량의 지표 Chl-a의 농도 비교결과 죽거나 활성을 잃은 식물플랑크톤의 양이 평균 1.5배 많은 것으로 나타났다. 조사기간 동안 4개 보 지점의 Sediment trap 포집된 침강물 내 C:N비는 2.0~7.4 범위로, N;P비는 14.2~52.5 범위로, C/Chl-a비는 14.4~253.3의 범위로 나타났다. 일반적으로 조류의 C/Chl-a 비가 40으로 볼 때 본 연구에서 조사된 보 지점에서의 침강물은 외부로부터 유입된 유기물이 많은 것으로 판단된다. 본 연구에서는 조류의 침강속도는 조류의 종을 구분하지 않은 총 조류에 대한 것으로, 향후 보 구간에서 종 조성을 고려한 조류예측 모델을 향상시키기 위해서는 조류 종별에 대한 침강속도에 대한 연구할 필요가 있다.