허성구 Sung Gu Heo , 김남원 Nam Won Kim , 박윤식 Youn Shik Park , 김종건 Jong Gun Kim , 김성준 Seong Joon Kim , 안재훈 Jae Hun Ahn , 김기성 Ki Sung Kim , 임경재 Kyoung Jae Lim

DOI: Vol.24(No.2) 147-155, 2008

Because of increased nonpoint source runoff potential at highland agricultural fields of Kangwon province, effective agricultural management practices are required to reduce the inflow of sediment and other nonpoint source pollutants into the water bodies. The watershed-scale model, Soil and Water Assessment Tool (SWAT), model has been used worldwide for developing effective watershed management. However, the SWAT model simulated sediment values are significantly affected by the number of subwatershed delineated. This result indicates that the SWAT estimated watershed characteristics from the watershed delineation process affects the soil erosion and sediment behaviors. However, most SWAT users do not spend time and efforts to analyze variations in sediment estimation due to watershed delineation with various threshold value although topography falsification affecting soil erosion process can be caused with watershed delineation processes. The SWAT model estimates the field slope length of Hydrologic Response Unit (HRU) based on average slope of subwatershed within the watershed. Thus the SWAT ArcView GIS Patch, developed by using the regression relationship between average watershed slope and field slope length, was utilized in this study to compare the simulated sediment from various watershed delineation scenarios. Four watershed delineation scenarios were made with various threshold values (700 ha, 300 ha, 100 ha, and 75 ha) and the SWAT estimated flow and sediment values were compared with and without applying the SWAT ArcView GIS Patch. With the SWAT ArcView GIS Patch applied, the simulated flow values are almost same irrespective of the number of subwatershed delineated while the simulated flow values changes to some extent without the SWAT ArcView GIS Patch applied. However when the SWAT ArcView GIS Patch applied, the simulated sediment values vary 9.7% to 29.8% with four watershed delineation scenarios, while the simulated sediment values vary 0.5% to 126.6% without SWAT ArcView GIS applied. As shown, the SWAT estimated flow and sediment values are not affected by the number of watershed delineation significant compared with the estimated flow and sediment value without applying the SWAT ArcView GIS Patch.

Hydrological Response Unit, HRU, Soil and Water Assessment Tool, SWAT, Soil Erosion, SWAT ArcView GIS Extension Patch

배대열 Dae Yeul Bae , 김유표 Yu Pyo Kim , 안광국 Kwang Guk An

DOI: Vol.24(No.2) 156-163, 2008

This study was to introduce a methodology of ecological health assessment for efficient management and to provide some diagnostic results of the survey. We evaluated ecological health assessment at five sampling locations of Sikjang ountainous Stream using the index of biological integrity (IBI) and Qualitative Habitat Evaluation Index (QHEI) during May-October 2006. The health condition, based on the IBI model, averaged 32 and varied from 27 to 37 depending on the sampling sites. Thus, the stream health was judged as "good" to "fair" conditions. IBI values showed slight differences between upstream and downstream sites. Whereas, QHEI values varied from 75 (fair condition) to 196 (excellent condition) and QHEI at St. 4~5, indicating the downstream reach had significantly lower than the headwater site (St.1). Regression analyses also showed that QHEI values had a linear decrease from the headwater to downstream. This result indicated that habitat quality was rapidly degradated by human influence. Overall, data of IBI and QHEI suggested that the stream health was maintained well in the present but the habitat and biological quality were partially degradated in the downstream. So, the human interference should be minimized to protect the downstream environment.

Index of biological integrity, IBI, Mountainous stream, Qualitative habitat evaluation index, QHEI, Stream management

김현구 Hyun Koo Kim , 김정화 Joung Hwa Kim , 이연희 Youn Hee Lee , 이재호 Jae Ho Lee , 김산 San Kim

DOI: Vol.24(No.2) 164-168, 2008

Perchlorate, which is still unregulated, is found in tap water, posing a threat to public health. In and out of Korea, there is no clear standard for drinking water quality or discharge. To make matters worse, Perchlorate study is in its infancy in Korea. This research tracked fresh water and purified water of water purification facility A and B located at the city of D, where Nak-dong River is being utilized as the purified water. And it was found that purified water shows no particular pattern in Perchlorate concentrations but represented a higher level of concentration compared to fresh water. With utilizing the research results, the study sought the impact of activated-carbon treatment process on Perchlorate elimination and found out that Perchlorate concentrations increased 38% after the process. The result proves that conventional water purification process can`t eliminate Perchlorate. Therefore, it is reasonable that Perchlorate discharge from sources should be minimized.

Activated carbon, Drinking water treatment, Perchlorate, Treated water

이병수 Byung Soo Lee , 정용준 Yong Jun Jung , 박무종 Moo Jong Park , 길경익 Kyung Ik Gil

DOI: Vol.24(No.2) 169-173, 2008

A field monitoring was conducted in order to find out the discharge characteristics of non-point source pollutants in the agricultural area. Event Mean Concentration (EMC) of TSS, BOD5, CODMn, TP, TN was calculated based on the monitoring data of 10 rainfall events at agricultural watersheds. A significant relationship was observed from the correlation between EMCs and rainfall characteristics. The result shows that EMC ranges of 95% confidence intervals were 50.5~203 mg/L for TSS, 0.8~14.2 mg/L for BOD5, 4.2~20.7 mg/L for CODMn, 2.4~4.5 mg/L for TN and 0.2~0.5 mg/L for TP, respectively. The correlation coefficients between TSS and TP and between BOD5 and CODMn were found to be 0.912 and 0.961. But TN was lower correlated with other EMC factors. It was also found that rainfall characteristics was not correlated with EMCs.

Discharge characteristic, Event mean concentration, EMC, Kyongan watershed, Non-point source, NPS, Rainfall characteristics

장창원 Chang Won Jang , 김재구 Jai Ku Kim , 김동환 Dong Hwan Kim , 김범철 Bom Chul Kim , 박주현 Ju Hyun Park

DOI: Vol.24(No.2) 174-179, 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 (±1.49) mgC·L-1 in the mainstream sites and 7.09 (±1.48) mgC·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 0.03 day-1. Mean decomposition rates of LPOC ranged from 0.10 day-1, and that of LDOC was approximately 0.08 day-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.

Decomposition rate, Dissolved organic carbon, Kum River, Particulate organic carbon

장수형 Su Hyung Jang , 이지호 Ji Ho Lee , 유철상 Chul Sang Yoo , 한수희 Su Hee Han , 김상단 Sang Dan Kim

DOI: Vol.24(No.2) 180-184, 2008

A distributed hydrologic model of an urban drainage area on Bugok drainage area in Oncheon stream was developed and combined with a optimization method to determine the optimal location and number of best management practices (BMPs) for storm water runoff reduction. This model is based on the SCS-CN method and integrated with a distributed hydrologic network model of the drainage area using system of 4,211 hydrologic response units (HRUs). Optimal location is found by locating HRU combination that leads to a maximum reduction in peak flow at the drainage outlet in this model. The results of this study indicate the optimal locations and numbers of BMPs, however, for more exact application of this model, project cost and SCS-CN reduction rate of structural facilities such infiltration trench and pervious pavement will have to be considered.

Best management practice, Hydrologic model, Optimization, Storm water runoff reduction

허성구 Sung Gu Heo , 전만식 Man Sig Jun , 박상헌 Sang Hun Park , 김기성 Ki Sung Kim , 강성근 Sung Keun Kang , 옥용식 Yong Sik Ok , 임경재 Kyoung Jae Lim

DOI: Vol.24(No.2) 185-194, 2008

There is increased soil erosion potential at highland agricultural crop fields because of its topographic characteristics and site-specific agricultural management practices performed at these areas. The agricultural upland fields are usually located at the sloping areas, resulting in higher soil loss, pesticides, and nutrients in case of torrential rainfall events or typhoon, such as 2002 Rusa and 2003 MaeMi. At the highland agricultural fields, the soil reconditioning have been performed every year to decrease damage by continuous cropping and pests. Also it has been done to increase crop productivity and soil fertility. The increased amounts of soil used for soil reconditioning are increasing over the years, causing significant impacts on water quality at the receiving water bodies. In this study, the field investigation was done to check soil reconditioning status for potato, carrot, and cabbage at the Doam-dam watershed. With these data obtained from the field investigation, the Soil and Water Assesment Tool (SWAT) model was used to simulate the soil loss reduction with environment-friendly and agronomically enough soil reconditioning. The average soil reconditioning depth for potato was 34.3 cm, 48.3 cm for carrot, and 31.2 cm for cabbage at the Doam-dam watershed. These data were used for SWAT model runs. Before the SWAT simulation, the SWAT ArcView GIS Patch, developed by the Kangwon National University, was applied because of proper simulation of soil erosion and sediment yield at the sloping watershed, such as the Doam-dam watershed. With this patch applied, the Coefficient of Determination (R2) value was 0.85 and the Nash-Sutcliffe Model Efficiency (EI) was 0.75 for flow calibration. The R2 value was 0.87 and the EI was 0.85 for flow validation. For sediment simulation, the R2 value was 0.91 and the EI was 0.70, indicating the SWAT model predicts the soil erosion processes and sediment yield at the Doam-dam watershed. With the calibrated and validated SWAT for the Doam-dam watershed, the soil erosion reduction was investigated for potato, carrot, and cabbage. For potato, around 19.3 cm of soil were over applied to the agricultural field, causing 146% of more soil erosion rate, approximately 33.3 cm, causing 146% of more soil erosion for carrot, and approximately 16.2 cm, causing 44% of more soil erosion. The results obtained in this study showed that excessive soil reconditioning are performed at the highland agricultural fields, causing severe muddy water issues and water quality degradation at the Doam-water watershed. The results can be used to develop soil reconditioning standard policy for various crops at the highland agricultural fields, without causing problems agronomically and environmentally.

Calibration, Soil and water assessment tool, SWAT, Soil erosion, Soil recondition, Streamflow, SWAT ArcView GIS extension patch, Validation

정주용 Ju Yong Jeong , 이경희 Kyong Hee Lee

DOI: Vol.24(No.2) 195-200, 2008

To analyze the riverine microbial community structure, genetic fingerprints and ecological indexes such as species abundances, diversity, evenness, dominance of targeted rivers in Gyeonggi Province were acquired and evaluated using terminal restriction fragment length polymorphism (T-RFLP) technique. Genetic fingerprinting technique such as T-RFLP, which is able to show the microbial community clearly unlike traditional culture-dependent techniques, was thought to be useful to analyse the riverine microbial ecosystem under various factors. Riverine ecosystem evaluation using visible organisms would give biased results with time, targeted organism and researcher. But, T-RFLP, which can exclude the subjected biases such as culture condition and identification, would be an option to understand natural ecosystem by including the microorganisms that defy culture but perform important functions.

Culture-dependent, Ecological indexes, Riverine, Terminal restriction fragment Length polymorphism, T-RFLP

권구호 Koo Ho Kwon , 이상협 Sang Hyub Lee , 민경석 Kyung Sok Min

DOI: Vol.24(No.2) 201-205, 2008

The korean government started to ban the sanitary landfill of food wastes as of 2005. The radical change of policy is primarily due to the limited landfill site, but aimed to promote not only to reduce the food waste production but also to enhance the reuse and recycle. The performance of elutriated acid fermentation to evaluate the effects of elutriating ratios was investigated. The fermenters were operated with elutriating water to food waste volumetric ratio of 2, 1, 0.5 and 0.25. Initial pH of elutriating water was set for 9 based on the pH effects study. The cumulative amounts of SCOD production rate were 0.34 gSCOD/gVSi, 0.45 gSCOD/gVSi, 0.26 gSCOD/gVSi and 0.28 gSCOD/gVSi with the ratios of 2, 1, 0.5 and 0.25, respectively. The cumulative productions of VFAs were 0.12 gVFAs as COD/gVSi, 0.28 gVFAs as COD/gVSi, 0.21 gVFAs as COD/gVSi and 0.14 gVFAs as COD/gVSi with the ratios of 2, 1, 0.5 and 0.25, respectively. The volume reduction were 58%, 52%, 45% and 47% with the ratios of 2, 1, 0.5 and 0.25, respectively.

Elutriated acid fermentation, Food waste, Solubilization, VS reduction

변명섭 Myeong Seop Byeon , 박혜경 Hae Kyung Park , 이완옥 Wan Ok Lee , 공동수 Dong Soo Kong

DOI: Vol.24(No.2) 206-213, 2008

Fish fauna and community structure were investigated at 2003, 2004 and 2006 in Lake Paldang and its inflows. In this survey, we collected 54 species belong to 14 families. Family Cyprinidae take 51.9% (28 species), Cobitidae and Gobiidae occupied 7.4% (each 4 species), respectively. E. erythropterus (11.8%) was dominant species and L. macrochirus (10.2%), designated as an ecosystem-invasive alien fish species by Ministry of Environment, M. yaluensis (9.1%), Z. platypus (7.7%) and R. brunneus (6.7%) were dominated in turn. H. molitrix, C. lutheri, P. altivelis, S. microdorsalis, L. costata. S. gracilis majimae, A. rivularis, P. koreanus. S. scherzeri and O. platycephala were rare species (less than 0.1% in relative abundance). In-lake area, 36 species of fishes belonging to 11 families were collected, and 48 species of 13 families were from inflows. The number of Korean endemic species were 19 species (35.2%), and 4 kinds of exotic species (7.4%), that is, C. cuvieri, H. molitrix, L. macrochirus and M. salmoides were found at this survey area. It was revealed by the analysis of fish community that diversity and richness indices were prominent at tributaries, and dominance index was high at the main body of Lake Paldang. Fish fauna showed rapid decline after dam construction which make the mid-Han river systems to lentic ecosystem, so many of meander-riffle fishes were disappeared dramatically. But after 1990s when installation of small scale wastewater treatment plants started in watershed, the water quality of small tributaries was improved. And also, expansion of the natural macrophytic vegetation of littoral zone should contribute to the development of diverse fish fauna in Lake Paldang.

Biological indices, E. erythropterus, Fish fauna, Lake Paldang

이영옥 Young Ok Lee

DOI: Vol.24(No.2) 214-220, 2008

Nitrifying bacteria were detected by fluorescent in situ hybridization (FISH) method at 6 sampling sites with different eutrophication degree in the Nak-Dong River and their tributaries. And conventional physico-chemical parameters including NH4-N, NO3-N, and TN were determined concurrently. In rainy period (July), there was no noticeable difference between the number of ammonia/nitrite-oxidizing bacteria detected at each site except Sang-Ju and the ratio of nitrifying bacteria to total counts stained by DAPI varied in 6~33%. By contrast, in the dry period (October), both of bacterial population was increased differently and the ratio of nitrifying bacteria to total counts ranged more widely from 6% in heavily polluted water zone, Hwa-Won to 60% in upper tributary with high agricultural land use. Byung-Sung-Chun. In January, the numbers of ammonia-oxidizing bacteria was reduced up to one tenth, while those of nitrite-oxidizing bacteria was apparently increased maybe due to high DO and low DOC.

Agricultural Land use, Eutrophication degree, Fluorescent in situ hybridization, FISH, Nak-Dong river, Nitrifying bacteria

유철상 Chul Sang Yoo , 김경준 Kyoung Jun Kim , 윤주환 Zu Hwan Yun

DOI: Vol.24(No.2) 221-229, 2008

This study revised a model for hydrologically analyzing rainwater harvesting facilities considering their rainfall-runoff properties and the data available. This model has only a few parameters, which can be estimated with rather poor measurements available. The model has a non-linear module for rainfall loss, and the remaining rainfall excess (effective rainfall) is assumed to be inflow to the storage tank. This model has been applied for the rainwater harvesting facilities in Seoul National University, Korea Institute of Construction Technology, and the Daejon World Cup Stadium. As a result, the runoff coefficients estimated were about 0.9 for the building roof as a rainwater collecting surface and about 0.18 for the playground. This result is coincident with that for designing the rainwater harvesting facilities to show the accuracy of model and the simulation results.

Inflow, Long-term rainfall-runoff analysis, Rainwater utilization, Runoff coefficient

김경준 Kyoung Jun Kim , 유철상 Chul Sang Yoo , 윤주환 Zu Hwan Yun

DOI: Vol.24(No.2) 230-238, 2008

This study evaluated the economic aspect of the rainwater harvesting facilities by hydrologically analyzing the inflow, rainwater consumption, rainfall loss, tank storage, and overflow time series to derive the net rainwater consumption and the number of days of rainwater available. This study considers several rainwater harvesting facilities in Seoul National University, Korea Institute of Construction Technology and Daejon World Cup Stadium and the results derived are as follows. (1) Increasing the water consumption decreases the number of days of rainwater available. (2) Due to the climate in Korea, a larger tank storage does not increase the amount and the number of days of water consumption during wet season (June to September), but a little in October. (3) Economic evaluation of the rainwater harvesting facilities considered in this study shows no net benefit (private benefit). (5) Flood reduction effect of rainwater harvesting facilities was estimated very small to be about 1% even in the case that 10% of all the basin is used as the rainwater collecting area.

Available days, Flood absorption effect, Long-term rainfall-runoff model, Rainwater consumption, Rainwater utilization system

김상호 Sang Ho Kim , 이을래 Eul Rae Lee

DOI: Vol.24(No.2) 239-246, 2008

In this study, an optimized deterministic water-quality model was constructed to estimate water quality of a river and lake in the upstream basin of a dam. A stochastic water-quality analysis using reliability analysis technique was applied to the model. The model was tested in the 13.9 km reach from Maeil stage station of Kyechun to Hoengsung Dam of Sum River. After finding hydraulic characteristics from nonuniform flow analysis, Broyden-Fletcher-Goldfarb-Shanno (BFGS) optimization technique for model calibration was applied to determine optimum reaction parameters, and model verification was performed based on these. The stochastic model, using Mean First-Order Second-Moment (MFOSM) and Monte-Carlo methods, was applied to the same reach as the deterministic study. Variations of discharge and water quality in headwater were considered, as well as variations of hydraulic coefficients and reaction coefficients. The statistical results of output variables from MFOSM were similar to those from the Monte-Carlo method. Risk analysis using MFOSM and Monte-Carlo methods presented the probabilities of some locations in the Hoengsung Lake violating existing water-quality standards in terms of DO and BOD.

Hoengsung Dam, QUAL2E model, Reliability analysis, Water-quality analysis

안윤주 Youn Joo An , 남선화 Sun Hwa Nam , 이재관 Jae Kwan Lee

DOI: Vol.24(No.2) 247-259, 2008

The utilization of a variety of hazard chemicals bears risks to human health and ecosystem. The increasing usage of various chemicals indicates the greater emission of those chemicals to water system, and the subsequent deterioration of water quality. Water system is vulnerable to many pollutants, however, there are limitations of managing a range of hazard chemicals based on insufficient legal foundations. Therefore it is needed to select hazard chemicals that can be potentially discharged into water system, and subsequently to classify a wide range of existing chemicals for better management of those chemicals. In this study, the 259 candidate chemicals of concern were selected from the lists of the toxic released inventory chemicals (148), hazard concern candidate chemicals (106), and wastewater effluent standard candidate chemicals (116). We suggested the category 1, 2, 3 and 4 of hazard chemicals potentially discharged into water system. The assessment factors considered for the classification were hazard potential, persistence and emission to water body. This work was conducted as a part of the project entitled ``Development of integrated methodology for evaluation of water environment``, and the results were used to develop the monitoring lists of hazard chemicals in four major rivers in Korea.

Categorization, Hazard chemical, Risk, Water quality, Water system