• Title/Summary/Keyword: Water quality level model

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Water Quality Modelling of the Keum River - Effect of Yongdam Dam (용담댐의 영향분석을 위한 금강의 수질모델링)

  • Lee, Eun-Hyung;Seo, Dong-Il
    • Journal of Korea Water Resources Association
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    • v.35 no.5
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    • pp.525-539
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    • 2002
  • Effects of Yongdam Dam discharge conditions on water quality of the Keum River and Daechung Lake inflow were analyzed for various scenarios using WASP5 water quality model. Three different groups of scenarios were tested: 1) Two different weather conditions; the lowest flow year and the highest flow year since the beginning of Daechung Dam operation in 1981, 2) Fine discharge flow rates; 5.4, 8.9, 12.4, 16.4 ㎥/s and field observed flow during the study period, 3) Three conditions of discharge water quality; first grade, second grade by Korean water quality standard and field observed water quality. Effect of changes in Yongdam Dam discharges was greater for dry year. The increase of discharge from the Yongdam Dam will improve water quality of downstream areas only when the water quality of the discharge is equal or better than that of downstream areas. Field observed water qualify data show that BOD concentrations are lower than first grade level but TN and TP concentrations are exceeding 5th and 3rd grade level in Korean standard, respectively. Considering that nutrient control methods in watershed areas of Yongdam dam are limited, it is expected that nutrient concentrations from Yongdam Dam discharge will be higher than 2nd grade water quality standard level. Therefore, it would be important to develop practical management strategies in the watershed area of Yongdam Dam based on field conditions for conservation of water quality in downstream areas.

Analysis of Water Quality Variation by Lowering of Water Level in Gangjeong-Goryong Weirin Nakdong River (낙동강 강정고령보 수위저하 운영에 따른 수질 변동특성 분석)

  • Park, Dae-Yeon;Park, Hyung-Seok;Kim, Sung-Jin;Chung, Se-Woong
    • Journal of Environmental Impact Assessment
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    • v.28 no.3
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    • pp.245-262
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    • 2019
  • The objectives of this study were to construct a three-dimensional water quality model (EFDC) for the river reach between Chilgok Weir and Gangjeong-Goryong Weir (GGW) located in Nakdong River, and evaluate the effect of hydraulic changes, such as water level and flow velocity, on the control of water quality and algae biomass. After calibration, the model accurately simulated the temporal changes of the upper and lower water temperatures that collected every 10 minutes, and appropriately reproduced changes in organic matter, nitrogen, phosphorus, and cyanobacteria. However, the simulated values were overestimated for the diatoms and green algae cell density, possibly due to the uncertainties of the parameters associated with algae metabolism and the lack of zooplankton predation function in the simulations. As a result of scenario simulation of running the water level of GGW from EL. 19.44 m to EL. 14.90 m (4.54 m drop), Chl-a and algae cell density decreased significantly.In particular,the cyanobacteria on the surface layer, which causes algal bloom, declined by 56.1% in the low water level scenario compared to the existing management level. The results of this study are in agreement with the previous studies that maintenance of critical flow velocity is effective for controlling cyanobacteria, and imply that hydraulic control such as decrease of water level and residence time in GGW is an alternative to limit the overgrowth of algae.

Analysis of the Water Quality by Various Gate Operation Effects at Nakdong Estuary Barrier (낙동강하구둑 수문운영에 따른 수질 영향 분석)

  • Lee, Sang Jin;Ryoo, Kyong Sick;Hwang, Man Ha;Lee, Sang Uk
    • Journal of Korean Society on Water Environment
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    • v.24 no.6
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    • pp.651-658
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    • 2008
  • Estuary barrier is a hydraulic structure constructed to supply safely water as protecting chlorine penetration of sea water. However, the barrier brings about a problem which decreases original functions of estuary because hydraulic ecology was disrupted as obstructing natural water exchange between fresh water and sea water. It is important to supply Enough fresh water in the estuary ecosystem. But it is possible to reduce the problems brought from barrier throughout efficient water gate operation of estuary barrier. It was shown in this study that the environmental effect of estuary in Nakdong river was investigated according to the control of water level. Also, the basic information about the effective water gate operation was provided. The analysis results showed that the release rate of estuary was increased about 20% as changing the operational water levels. This helps supplying fresh water durably to the mixing zone. Also, CE-QUAL-W2 model was utilized to assess water quality. The values of BOD and COD were not changed in estuary area. From the result, it was analyzed the effect of water quality according to the water gate operation was not indicated.

A study of statistical analysis method of monitoring data for freshwater lake water quality management (담수호 수질관리를 위한 측정자료의 통계적 분석방법 연구)

  • Chegal, Sundong;Kim, Jin
    • Journal of Korea Water Resources Association
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    • v.57 no.1
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    • pp.9-19
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    • 2024
  • As using public monitoring data, analysing a trends of water quality change, establishing a criteria to determine abnormal status and constructing a regression model that can predict Chlorophyll-a, an indicator of eutrophication, was studied. Accordingly, the three freshwater lakes were selected, approximately 20 years of water quality monitoring data were analyzed for periodic changes in water quality each year using regression analysis, and a method for determining abnormalities was presented by the standard deviation at confidence level 95%. By calculating the temporal change rate of Chlorophyll-a from irregular observed data, analyzing correlations between the rate and other water quality items, and constructing regression models, a method to predict changes in Chlorophyll-a was presented. The results of this study are expected to contribute to freshwater lake water quality management as an approximate water quality prediction method using the statistical model.

Comparative Analysis of QUAL2E, QUAL2K and CAP Steady State Water Quality Modeling Results in Downstream Areas of the Geum River, Korea (QUAL2E, QUAL2K 및 CAP 모델을 이용한 금강 하류 하천구간 정상상태 수질모델링 결과 비교 분석)

  • Seo, Dongil;Yun, Jong Uk;Lee, Jae Woon
    • Journal of Korean Society of Water and Wastewater
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    • v.22 no.1
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    • pp.121-129
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    • 2008
  • Major factors affecting water quality in rivers are transportation, input of pollutant loads and kinetic transformation of pollutants. Government level decision makings on water quality management are based on steady state water quality modeling. However, it is more than often that such a steady state assumption is far from real situations in rivers. Therefore, it is unavoidable to have modeling errors in water quality modeling especially for steady state modeling for longer period of time. Authors attempted to identify sources of errors in results of steady state models and thus tried to find out ways to minimize those errors. Three water quality models, QUAL2E (Brown et al., 1983), QUAL2K (Chapra et al., 2006) and CAP (Seo and Lee, 2000) were applied to the lower stream of the Geum River. $BOD_5$ and COD tend to underestimate observed data while TN and TP showed relatively smaller errors. QUAL2E model provided best calibration results for BOD5 and TP and QUAL2K model showed best calibration results for TN. Since these errors are only relative values, it was difficult to conclude which model is better performing in certain situations. The most probable reasons for errors in water quality modeling are; 1) inappropriate consideration on flow characteristics, 2) lack of information on incoming pollutant load and 3) inappropriate location of sampling for water quality analysis.

The Change of Coastal Water Area due to the Development of Mokpo Harbor and Construction of Daebul Industrial Complex(I) (목포항 개발 및 대불 산업단지 조성에 따른 연안해역 변화(I)- 해면 정온도를 중심으로 -)

  • 이중우;정명선
    • Journal of the Korean Institute of Navigation
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    • v.15 no.2
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    • pp.87-96
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    • 1991
  • The change of water level at Mokpo Harbour and its adjacent coastal area due to the construction of the Youngsan Estuary Barrage and the Third Land Reclamation Work of estuary barren had been roughly expected. Periodical floods, which occur 2 times per month, are also being observed at the low lying commercial areas near the Mokpo Old Harbor. Although it is said that the highest tidal current component among the tidal current records at the approaching channel to Mokpo Harbor is reduced to 6 kts, because of the esturary barrage, they do not give any precise statement or a deep analysis for the flooding and periodical water level change under certain environmental conditions. Moreover, they never tried the analysis of development plan considering the natural disaster such as typhoon or other extreme conditions. Thus, it is necessary to collect and analyze the data related to floodings, harbor oscillations, currents, and water quality , etc. because of the development considering the extreme condition. Thus, it is necessary to collect and analyze the data related to floodings, harbor oscillations, currents, and water quality, etc. because of the development considering the extreme condition and to evaluate the field observation and measurement, including the numerical model simulation based on the scientific approaches. This study deals the problem of the water level change among the integrated analyses of the coastal area changes. The result can be used for the integrated planning to give a strong foundation and it will contribute to the development of local area.

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Evaluation of Multi-classification Model Performance for Algal Bloom Prediction Using CatBoost (머신러닝 CatBoost 다중 분류 알고리즘을 이용한 조류 발생 예측 모형 성능 평가 연구)

  • Juneoh Kim;Jungsu Park
    • Journal of Korean Society on Water Environment
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    • v.39 no.1
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    • pp.1-8
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    • 2023
  • Monitoring and prediction of water quality are essential for effective river pollution prevention and water quality management. In this study, a multi-classification model was developed to predict chlorophyll-a (Chl-a) level in rivers. A model was developed using CatBoost, a novel ensemble machine learning algorithm. The model was developed using hourly field monitoring data collected from January 1 to December 31, 2015. For model development, chl-a was classified into class 1 (Chl-a≤10 ㎍/L), class 2 (10<Chl-a≤50 ㎍/L), and class 3 (Chl-a>50 ㎍/L), where the number of data used for the model training were 27,192, 11,031, and 511, respectively. The macro averages of precision, recall, and F1-score for the three classes were 0.58, 0.58, and 0.58, respectively, while the weighted averages were 0.89, 0.90, and 0.89, for precision, recall, and F1-score, respectively. The model showed relatively poor performance for class 3 where the number of observations was much smaller compared to the other two classes. The imbalance of data distribution among the three classes was resolved by using the synthetic minority over-sampling technique (SMOTE) algorithm, where the number of data used for model training was evenly distributed as 26,868 for each class. The model performance was improved with the macro averages of precision, rcall, and F1-score of the three classes as 0.58, 0.70, and 0.59, respectively, while the weighted averages were 0.88, 0.84, and 0.86 after SMOTE application.

Estimation on Chemical Water Quality Suitability Index for 4 Species of the Mayfly Genus Ephemera (Ephemeroptera: Ephemeridae) Using Probability Distribution Models (확률분포모형을 이용한 하루살이속(Ephemera) 4종에 대한 화학적 수질 적합도지수 평가)

  • Bongjun Jung;Dongsoo Kong
    • Journal of Korean Society on Water Environment
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    • v.39 no.6
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    • pp.475-490
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    • 2023
  • Chemical water quality suitability for species (Ephemera strigata, Ephemera separigata, and Ephemera orientalis-sachalinensis group) of the mayfly genus Ephemera (Order Ephemeroptera) was analyzed with probability distribution models (Exponential, Normal, Lognormal, Logistic, Weibull, Gamma, Beta, Gumbel). Data was collected from 23,957 sampling units of 6,664 sites in Korea from 2010 to 2021. E. orientalis-sachalinensis occurred at the range of BOD5 0.3~11.1 mg/L (the best-fit Lognormal model); T-P 0.007~0.769 mg/L (the Gumbel model); TSS 0.4~142.2 mg/L (the Lognormal model). E. strigata occurred at the range of BOD5 0.4~7.4 mg/L (the Gumbel model); T-P 0.007~0.254 mg/L (the Lognormal model); TSS 0.4~17.1 mg/L (the Lognormal model). E. separigata occurred at the range of BOD5 0.4~2.6 mg/L (the R-Weibull model); T-P 0.007~0.134 mg/L (the Lognormal model); TSS 0.7~10.0 mg/L (the Lognormal model). Habitat suitability range of E. orientalis-sachalinensis was estimated to be 0.4~1.9 mg/L (BOD5), 0.024~0.086 mg/L (T-P), 2.5~22.4 mg/L (TSS); that of E. strigata was 0.4~0.7 mg/L (BOD5), 0.007~0.018 mg/L (T-P), 0.0~1.7 mg/L (TSS); that of E. separigata was 0.0~0.4 mg/L (BOD5), 0.000~0.015 mg/L (T-P), 0.5~3.1 mg/L (TSS). In a relative comparision, E. orientalis-sachalinensis was estimated to be eurysaprobic, and narrowly adapted in high levels of T-P and TSS, E. strigata was estimated to be oligosaprobic and adapted in low levels of T-P and TSS, and E. separigata was estimated to be stenooligosaprobic and widely adapted in low level of T-P and TSS.

Implementation of Modeller and Simulator for Fish Farming Environmental Information using Petri-Net (페트리넷을 이용한 어류양식 환경 정보 모델러 및 시뮬레이터 구현)

  • Ceong, Hee-Taek;Cho, Hyug-Hyun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.3
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    • pp.626-634
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    • 2012
  • It is required that system can seamlessly identify and manage change history and comprehensive assessment of several types of data as well as individual information of feeding and water environment for scientific and systematic management of fish farming environment and fish farmer. In this study, we implemented the system which can present and simulate current status of water quality and feeding based on th historical data of them, and check changes of state step by step using visual C++. In addition, we proposed the entropy model which can be comprehensive analysis about water quality and feed status information based on knowledge of fisheries. It can be the foundation to create high-level environment model reflecting the more diverse fisheries knowledge such as disease.

Development and Application of the Ecosystem Model in Brackish Lake Obuchi, Japan (일본 기수호(Lake Obuchi)에서 생태계 모델의 개발과 적용)

  • Kondo, Kunio;Inaba, Jiro;Hosoda, Masahiro;Kutsukake, Hiroshi;Seike, Yasushi;Nakata, Kisaburo;Shinji, Ueda
    • Korean Journal of Ecology and Environment
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    • v.37 no.4 s.109
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    • pp.448-454
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    • 2004
  • In order to evaluate the water quality (N, P and C) and the biological mass balance of semi-enclosed brackish Lake Obuchi, Japan, an ecosystem model was developed and applied to the lake, using the flow field calculated by a hydrodynamic model. The time series data of the observed tide level, river discharge and meteorological parameters from January 2001 to December 2002 were incorporated as the parameters of the hydrodynamic model. Water quality and biomass balance were estimated by the ecosystem model, and simulated fluctuations In water quality agreed with our observations. The carbon contents of POC, phytoplankton and zooplankton in the lake were calculated by the model at an average 7200, 1500 and 22 kg, respectively, which somewhat agreed with our observations of POC (5900 kg), phytoplankton (3800kg), and zooplankton (150kg).