공동수 Dong Soo Kong , 최재완 Jae Wan Choi , 강현우 Hyun Woo Kang , 류지철 Ji Chul Ryu , 장춘화 Chun Hwa Jang , 금동혁 Dong Hyuk Gum , 임경재 Kyoung Jae Lim

DOI: Vol.28(No.3) 347-358, 2012

The SWAT (Soil and Water Assessment Tool) should be calibrated and validated with observed data to secure accuracy of model prediction. Recently, the SWAT-CUP (Calibration and Uncertainty Program for SWAT) software, which can calibrate SWAT using various algorithms, were developed to help SWAT users calibrate model efficiently. In this study, three algorithms (GLUE: Generalized Likelihood Uncertainty Estimation, PARASOL: Parameter solution, SUFI-2: Sequential Uncertainty Fitting ver. 2) in the SWAT-CUP were applied for the Soyang-gang dam watershed to evaluate these algorithms. Simulated total streamflow and 0~75% percentile streamflow were compared with observed data, respectively. The NSE (Nash-Sutcliffe Efficiency) and R2 (Coefficient of Determination) values were the same from three algorithms but the P-factor for confidence of calibration ranged from 0.27 to 0.81 . the PARASOL shows the lowest p-factor (0.27), SUFI-2 gives the greatest P-factor (0.81) among these three algorithms. Based on calibration results, the SUFI-2 was found to be suitable for calibration in Soyang-gang dam watershed. Although the NSE and R2 values were satisfactory for total streamflow estimation, the SWAT simulated values for low flow regime were not satisfactory (negative NSE values) in this study. This is because of limitations in semi-distributed SWAT modeling structure, which cannot simulated effects of spatial locations of HRUs (Hydrologic Response Unit) within subwatersheds in SWAT. To solve this problem, a module capable of simulating groundwater/baseflow should be developed and added to the SWAT system. With this enhancement in SWAT/SWAT-CUP, the SWAT estimated streamflow values could be used in determining standard flow rate in TMDLs (Total Maximum Daily Load) application at a watershed.

Auto-calibration, GLUE, PARASOL, SUFI-2, SWAT-CUP

안정민 Jung Min Ahn , 류경식 Kyong Sik Ryoo , 류시완 Si Wan Lyu , 이상진 Sang Jin Lee

DOI: Vol.28(No.3) 359-366, 2012

Accurate predictions about the water quality of a river have great importance in identifying in-stream flow and water supply requirements and solving relevant environmental problems. In this study, the effect of water release from upstream dam on the downstream water quality has been investigated by applying a hydological model combined with QUAL2E to Geum River basin. The ESP (Ensemble Stream Prediction) method, which has been validated and verified by lots of researchers, was used to predict reservoir and tributary inflow. The input parameters for a combined model to predict both hydrological characteristics and water quality were identified and optimized. In order to verify the model performance, the simulated result at Gongju station, located at the downstream from Daecheong Dam, has been compared with measured data in 2008. As a result, it was found that the proposed model simulates well the values of BOD, T-N, and T-P with an acceptable reliability.

Ensemble Stream Prediction, ESP, Qual2E, Streamflow Synthesis and Reservoir Regulation, SSARR, System coupled operation, Water quality forecasting

홍은정 Eun Jung Hong , 정팔진 Paul Gene Chung , 유승민 Seung Min Ryu , 박준석 Jun Seuk Park , 유승열 Seung Ryul Yoo , 노태협 Tai Hyeop Lho

DOI: Vol.28(No.3) 367-374, 2012

A flotation process has a shorter processing time and needs less space than a sedimentation process. Dissolved air flotation process (DAF) is an efficient flotation method and used in a conventional wastewater treatment process. However, DAF requires the circulation of water containing compressed air and requires expensive installation and operation cost. Plasma Air Flotation (PAF) process is able to float flocs by micro bubbles generated from underwater plasma without the circulation of bubbly water and additional saturators. Therefore, PAF can be an alternative solution overcoming economic barriers. In this study, Humic acid removal efficiency by PAF process was compared with that of sedimentation process. 44.67% and 87.3% reduction rate based on UV 254 absorbance has been measured in sedimentation and PAF respectively. In particular, PAF in the flocculation zone can dramatically remove humic acid from water. In flocculation zone, PAF can separate organic matters but sedimentation cannot.

Flotation process, Humic acid, Plasma, Plasma Air Flotation, PAF, Sedimentation

금동혁 Dong Hyuk Kum , 류지철 Ji Chul Ryu , 최재완 Jae Wan Choi , 신민환 Min Hwan Shin , 신동석 Dong Suk Shin , 천세억 Se Uk Cheon , 최중대 Joong Dae Choi , 임경재 Kyoung Jae Kim

DOI: Vol.28(No.3) 375-383, 2012

Soil erosion has been emphasized as serious environmental problem affecting water quality in the receiving waterbodies. Recently, Best Management Practices (BMPs) have been applied at a field to reduce soil erosion and its effectiveness in soil erosion reduction has been monitored with various methods. Although monitoring at fields/watershed outlets would be accurate way for these ends, it is not possible at some fields/watersheds due to various limitations in direct monitoring. Thus modeling has been suggested as an alternative way to evaluate effects of the BMPs. Most models, which have been used in evaluating hydrology and water quality at a watershed, could not reflect rainfall intensity in runoff generation and soil erosion processes. In addition, source codes of these models are not always public for modification/enhancement. Thus, runoff- sediment evaluation system using hourly rainfall data and vegetated filter strip (VFS) evaluation module at field level were developed using open source MapWindow GIS component in this study. This evaluation system was applied to Bangdongri, Chuncheonsi to evaluate its prediction ability and VFS module in this study. The NSE and R2 values for runoff estimation were 0.86 and 0.91, respectively, and measured and simulated sediment yield were 15.2 kg and 16.5 kg indicating this system, developed in this study, can be used to simulate runoff and sediment yield with acceptable accuracies. Nine VFS scenarios were evaluated for effectiveness of soil erosion reduction. Reduction efficiency of the VFS was high when sediment inflow was small. As shown in this study, this evaluation system can be used for evaluation BMPs with local rainfall intensity and variations considered with ease-of-use GIS interface.

Best Management Practices, BMPs, MapWindow, Open source GIS, Runoff, Sediment yield, Vegetated filter strip

신유리 Yu Ri Shin , 정지연 Ji Yeon Jung , 최정훈 Jung Hoon Choi , 정광욱 Kwang Wook Jung

DOI: Vol.28(No.3) 384-393, 2012

Saemangeum lake is an artificial lake created by reclamation works and an estuary embankment since 2006. The sea water flows into the lake by the operation of two sluice gates, and the freshwater enters into the lake by the upper streams. For the reflection of hydrology and hydrodynamics effects in Saemangeum area, a hydrodynamics model was developed by connecting Hydrological Simulation Program with Fortran (HSPF) and Environmental Fluid Dynamic Code (EFDC). The HSPF was applied to simulate the freshwater discharge from the upper steam watershed, and the EFDC was performed to compute water flow, water temperature, and salinity based on time series from 2008 to 2009. The calibration and validation are performed to analyze horizontal and vertical gradients. The horizontal trend of model simulation results is reflected in the trend of observed data tolerably. The vertical trend is conducted an analysis of seasonal comparisons because of the limitation of vertically observed data. Water temperature reflects on the seasonal changes. Salinity has an effect on the near river input spots. The impact area of salinity is depending on the sea water distribution by gate operation, mainly.

Environmental Fluid Dynamic Code, EFDC, Hydrological Simulation Program with Fortran, HSPF, Saemangeum, Salinity, Water temperature

홍성호 Sung Ho Hong , 반종석 Jong Seok Ban , 전항배 Hang Bae Jun

DOI: Vol.28(No.3) 394-400, 2012

We drew the stage-discharge relations of Byeokgye Stream, located in Yangpyeong-gun, Gyeonggi-do, and analysed the correlation between items of water pollutants by measuring the flow rate and water pollutants thirty-four times from April 2010 to December 2010. The results showed that it tended to be low water season from April to June and from October and December, while tending to be water season from July to September. The average flow rate was 2.137 m3/sec: 0.464 m3/sec in low water season and 13.970 m3/sec in high water season. The stage-discharge curve thereon was . As to the correlations, the correlation between the water temperature and COD was 0.58, and the correlations of SS with BOD and COD were 0.46 and 0.40 respectively. The correlation between SS and T-P was 0.73, showing higher than other items.

Correlation, Flow rate, Stage-discharge curve, Water quality monitoring

김동석 Dong Seog Kim , 박영식 Young Seek Park

DOI: Vol.28(No.3) 401-408, 2012

High-voltage dielectric discharges are an emerging technique in environmental pollutant degradation, which that are characterized by the production of hydroxyl radicals as the primary degradation species. The initiation and propagation of the electrical discharges depends on several physical, chemical, and electrical parameters such as 1st and 2nd voltage of power, gas supply, conductivity and pH. These parameters also influence the physical and chemical characteristics of the discharges, including the production of reactive species such as·OH, H2O2 and O3. The experimental results showed that the optimum 1st voltage and air flow rate for RNO (N-Dimethyl-4-nitrosoaniline, indicator of the generation of OH radical) degradation were 160 V (2nd voltage of is 15 kV) and 4 L/min, respectively. As the increased of the 2nd voltage (4 kV to 15 kV), RNO degradation, H2O2 and O3 generation were increased. The conductivity of the solution was not influencing the RNO degradation and H2O2 and O3 generation. The effects pH was not high on RNO degradation. However, the lower pH and the conductivity, the higher H2O2 and O3 generation were observed.

Dielectric barrier discharge, H2O2, O3, OH radical, Oxidants, Plasma

장재호 Jae Ho Jang , 안종호 Jong Ho Ahn

DOI: Vol.28(No.3) 409-417, 2012

SWAT model was applied for the Nakdong River Basin to characterize water quality variability and assess the feasibility of using the load duration curve to water quality management. The basin was divided into 67 sub-basins considering various watershed environment, and rainfall runoff and pollutant loading were simulated based on 6 year measurements of meteo-hydrological data, discharge data of treatment plants, and water quality data (SS, T-N and T-P). The results demonstrate that non-point source loads during wet season increase by 80~95% of total loads. Although the rate of water flow governs the amount of SS that is transported to the main streams, nutrient concentrations are highly elevated during dry season by being concentrated. This phenomenon is more pronounced in the lower basin, receiving large amounts of urban point source discharges such as treated sewages. Also, the load duration curves (LDC) demonstrate dominant source problems based on the load exceedances, showing that SS concentrations are associated with the rainy season and nutrients, such as T-P, may be more concentrated at low flow and more diluted at higher flow. Overall, the LDC method could be used conveniently to assess watershed characteristics and pollutant loads in watershed scale.

Load Duration Curve, LDC, Nakdong River Basin, Pollutant Loads, SWAT model, Water quality management

박미숙 Mi Sook Park , 이재용 Jae Yong Lee , 정성민 Sung Min Jung , 박창근 Chang Keun Park , 장군 Kun Chang , 김범철 Bom Chul Kim

DOI: Vol.28(No.3) 418-425, 2012

Dam construction in a river can change its hydrological pattern and trap sediments, which results in ecological changes in the downstream. It is a common phenomenon in the downstream of dams to have decreased sediment flow and increased periphyton. Artificial floods and sediment application are suggested as mitigation practices in order to simulate natural process of flood; transporting sediment and sloughing periphyton off. In this study the effects of artificial floods on periphyton were examined by applying sand artificially and discharging water from a dam (Yangyang Dam, Korea). The study area has been suffering from turbidity problems caused by shore erosion of the dam. The accumulation of inorganic sediments and increase of periphyton on the river bottom are the major factors of habitat deterioration in the downstream reaches. Artificial flood and artificial addition of sand was performed in summer and the effects were measured. Piles of applied sands were washed off easily by discharge and it enhanced the periphyton sloughing effect. The removal efficiency of periphyton was 50~80% within the 2 km reach from the dam. In conclusion artificial floods and sand application can be a good mitigation measure for the habitat rehabilitation after a dam construction in streams.

Artificial flood, Removal efficiency of periphyton, Sediment, The Hoo stream, Yangyang Dam

박준대 Jun Dae Park , 오승영 Seung Young Oh , 최윤호 Yun Ho Choi

DOI: Vol.28(No.3) 426-435, 2012

The variation of stream flow is the one of the most important factors which influence on that of water quality in the unit watershed. The target water quality goal is established and permissible load is allotted in the base of the standard flow condition along with its water quality for the management of Total Maximum Daily Loads (TMDLs). A standard flow selected could cause problems in the load allotment if it was not properly arranged. This study reviewed the acquisition of water quality data, the self-variation and the retainability in water quality on the specific flow conditions. This study also proposed the median and the adjusted average flow condition out of general flow conditions as alternative standard flow conditions. It is considered that the alternatives can make the water quality data easily acquired and the water quality representativeness more enhanced on the standard flow conditions.

General flow conditions, Specific flow conditions, Standard flow conditions, Total Maximum Daily Loads, Water quality variation

신민환 Min Hwan Shin , 장정렬 Jeong Ryeol Jang , 원철희 Chul Hee Won , 최용훈 Young Hun Choi , 신재영 Jae Young Shin , 임경재 Kyoung Jae Lim , 최중대 Joong Dae Choi

DOI: Vol.28(No.3) 436-443, 2012

This research was focused on the effect of rice straw and rice straw mat on the reduction of upland field non-point source (NPS) pollution discharges. Six experimental plots of 5×22 m in size and 3% in slope prepared on gravelly sandy loam soil were treated with control, rice straw cover and rice straw mat cover. Radish in Spring growing seasons were cultivated. NPS pollution discharge was monitored and compared with respect to the treatments. The surface cover rate of rice straw and rice straw mat right after the treatments was 64.7% and 73.7%, respectively. Rainfall of the 16 monitored events ranged from 12.8 mm to 538.2 mm. Runoff coefficient of the events was 0.01~0.67 in control plot, 0~0.63 in rice straw plot and 0~0.45 in rice straw mat plot. The reduction of runoff compared to the control plot was 5.4~99.7% in rice straw plot and 32.9~100% in rice straw mat plot. The reduction of NPS pollution load was 52.0% for SS, 28.5% for T-N and 35.2% for T-P in rice straw plot and 79.8% for SS, 68.3% for T-N and 53.3% for T-P in rice straw mat plot. This research revealed that rice straw mat cover on the soil surface could not only increase the crop yield and farmer`s income but also reduce the NPS pollution loads significantly.

NPS pollution, Radish, Runoff, Surface cover material

이건행 Keon Haeng Lee , 정유진 Eu Gene Chung , 김경현 Kyung Hyun Kim , 유정아 Jeong Ah Yu , 이은정 Eun Jeong Lee

DOI: Vol.28(No.3) 444-452, 2012

This study aims at assessing vulnerability of water quality and aquatic ecosystem to climate change by using proxy variables. Vulnerability to climate change is defined as a function of exposure to climate, sensitivity, and adaptive capacity. Detailed proxy variables were selected considering availability and then standardized by re-scaling concept. After adequate weights were assigned to standardized proxy variables by Delphi technique, vulnerability index was calculated. As results, vulnerability of adjacent regions to coastal areas include water quality and aquatic ecosystem is relatively higher than that of inland areas, and especially adjacent region to the western and southeast seas, and Jeju show high vulnerabilities. Vulnerability in the future was performed based on A1B scenario (IPCC, 2000). Temporally, the increase of vulnerability from 2050s to 2100s may be larger than the increase from 2000s to 2050s. Because vulnerability index was estimated through the relationship among various proxy variables, it is important to consider characteristics of local region with measurements and policies for reduction of sensitivity and enhancement of adaptive capacity on climate change. This study is expected to be useful in planning adaptation measures and selecting priority to the policy on climate change.

Climate change, Delphi survey, Proxy variables, Vulnerability assessment

최용훈 Yong Hun Choi , 원철희 Chul Hee Won , 박운지 Woon Ji Park , 신민환 Min Hwan Shin , 신재영 Jea Young Shin , 이수인 Su In Lee , 최중대 Joong Dae Choi

DOI: Vol.28(No.3) 453-459, 2012

In this study, Song-Cheon river Basin located at Dae-kwan-lyong Meyn in Kang-Won Province was monitored to analyze characteristics of non-point source pollution during the snowmelt period. The characteristics of NPS pollution such as runoff, change in water quality and pollutant loads by snowmelt were investigated from 23th February 2010 to 27th April 2010. The results showed that The climate change effects flow, turbidity and concentration of SS and COD with showing similar trend of fluctuation. Daily pollutant loads per unit area were SS 74.43 kg/ha/day, COD 1.25 kg/ha/day, BOD 0.21 kg/ha/day, TN 0.717 kg/ha/day, TP 0.141 kg/ha/day and the flow weight mean concentration has been SS 985.97 mg/L, COD 16.28 mg/L, BOD 2.67 mg/L, TN 9.302 mg/L, TP 1.834 mg/L, respectively. The flow and pollutant loads both of SS and of COD significantly increased during the snowmelt period. Because structurally loosen soil by freezing and thawing deteriorates water quality, research and management measures will be needed.

Flow weight mean concentration, Non-Point Source, NPS, Pollutant Loads, Snowmelt

최진수 Jin Su Choi , 엄철용 Chul Yong Um , 주경훈 Kyoung Hoon Chu , 함석현 Seok Heon Ham , 이종혁 Jong Hyeok Lee , 유성수 Sung Soo Yoo , 고광백 Kwang Baik Ko

DOI: Vol.28(No.3) 460-466, 2012

Perchlorate is used in a number of applications as an oxidizer in solid propellants, munitions and fireworks and is one of the endocrine disrupting chemicals, which interferes with iodide uptake into the thyroid gland. The purpose of this study was to investigate perchlorate occurrence and distribution with a results of analysis of 94 samples collected from military facilities in Korea from October 11 to October 23, 2011. Overall, among all of the 94 samples analyzed, perchlorate was detected in 6.4% of the total number of samples above 4 μg/L (minimum reported limit) and the average concentration was 26.1 μg/L and the maximum concentration was 107.7 μg/L which was observed in surface water near manufacturing site of ammunition. By site classification, perchlorate was detected at one site in 4 manufacturing sites of ammunition and the maximum concentration was 107.7 μg/L which was six times higher than that in guideline for perchlorate in Nakdong River and resulted from point source discharge. Perchlorate was detected at 3 sites in 78 measurements for shooting area and the maximum concentration was 12.4 μg/L which was collected in dringking water and perchlorate in another sample was detected above MRL in shooting area was collected right away after shooting. These results showed that long term monitoring was needed considering weather conditions and shooting schedules.

Military facilities, Perchlorate, Pollution Level, Water type

김요용 Yo Yong Kim , 우정식 Jung Sik Woo , 황선민 Sun Min Hwang , 김문정 Moon Jeong Kim

DOI: Vol.28(No.3) 467-472, 2012

In this study, water quality and acute toxicity using Daphnia magna were analyzed to investigate the eco-toxicological substances identified as statistical analysis and propose a management plan for the effluent of Banwol industrial complex, Ansan, Gyeonggi-do. Cu, Zn, F, Mn concentrations in the effluent far exceeded the US standards to protect the aquatic ecosystem and eco-toxicity values were 5~22 TU. However, concentrations of heavy metals significantly decreased after Ansan public wastewater treatment plant operating a biological treatment and toxicity values were 0 TU. Zn, Cr, F and Cu in the effluent showed very strong and strong positive correlations with eco-toxicity values, respectively. Regression analysis resulted in an equation between toxicity and Zn, TU = 4.884×Zn (mg/L)-0.391 showing Zn concentration should be managed less than 0.285 mg/L to keep the eco-toxicity (TU) less than 1.

Correlation, Eco-toxicity, Industrial drainages, Public wastewater treatment plant, Regression analysis

곽진일 Jin Il Kwak , 윤성지 Sung Ji Yoon , 남선화 Sun Hwa Nam , 안윤주 Youn Joo An

DOI: Vol.28(No.3) 473-478, 2012

To protect human health and manage increasing hazardous chemicals in stream area, it is necessary to expand water quality hazardous items based on risk assessment with proper monitoring data. Also, it is essential to set up the suitable monitoring frequency to produce reliable exposure data to derive water quality guidelines. However, there has been no harmonized monitoring frequency for risk assessment in both domestic and international monitoring systems. In addition, the monitoring frequency for risk assessment has been selected as ``Research needs`` in the International Conference on Deriving Environmental Quality Standards for the Protection of Aquatic Ecosystems (EQSPAE) of 2011. In this study, Cases of UNEP/WHO, EU, European countries, USEPA, ANZECC/ARMCANZ, CCME, Japan, and Korea were analyzed to propose the monitoring frequency for risk assessment. Monitoring frequencies depending on environmental conditions, monitoring object, measurement parameters, and monitoring duration were extensively collected. We observed that a monthly monitoring has been applied at most of organizations including EU, USEPA, and UNEP/WHO. In this study, monitoring frequency of minimum 6 times during 3 years were proposed to conduct the risk assessment based on the current domestic status. However, it is necessary to make agreements among interested parties, and perform additional studies about optimal monitoring frequency to protect the aquatic ecosystem and human health in Korean rivers and streams.

Exposure assessment, Hazardous chemicals, Monitoring frequency, Risk assessment, Water quality monitoring

주성희 Sung Hee Joo , 박종민 Jong Min Park , 이양우 Yang Woo Lee

DOI: Vol.28(No.3) 479-482, 2012

Membrane process has been one of the widely applied wastewater treatment options, especially in field. However, one of the tricky issues in the process is to treat concentrates generated from reverse osmosis (RO) system in a manner of saving cost with maximum efficiency for treating a wide range of contaminants. Stimulated with the challenging issues, we have conducted a series of experimental studies in the evaluation for removing organics and nutrients using activated carbon. Results indicated that while powdered activated carbon (PAC) efficiently removed organics and the extent of removal was proportional to the PAC dosage, little removal of nitrogen and phosphorus was observed despite increasing the PAC dose. Interestingly, applying PAC was superior in removing organics than using granular activated carbon (GAC). These results suggest smaller particle size with higher surface area could provide greater chemical reactivity in removing organics.

Dissolved organic carbon, Granular activated carbon, Powdered activated carbon, Reverse osmosis concentrate, Total nitrogen, Total phosphorus