• Journal of Wetlands Research
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• v.16 no.1
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• pp.1-10
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• 2014

The research grasps water quality contamination source by investigating the data that are superordinate laws and the related plans implemented for establishing water quality improvement measures of upper stream for Chung-Ju Dam, present conditions of the hydraulic and hydrology, the present conditions and plans of environment basic facilities, and present conditions of main contamination source's occurrence load and discharge load, etc. The research used the QUAL2E simulation which is being widely applied to simulation of river water quality because the QUAL2E has high credibility among water quality simulations known throughout the country. On basis of this research, regulations and politic alternatives are required in order to water quality improvement upper stream for the Chung-ju dam, especially establishing processing facilities in the region where loading amount is concentrated should be considered with the additional research regarding cost-efficient facility of pollution source.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 1994.05a
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• pp.51-53
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• 1994

담수는 인간의 생존에 필수적인 요소이다. 우리는 매일 일정량의 물을 섭취하고 있으며, 일상에서 직접, 간접적으로 물과 관련되지 않고서는 생활할 수 없다. 지구 표면의 약 70%가 물로서 덮여 있다고는 하지만 인간의 생활에 직접적인 이용가치가 있는 담수(지표수)는 전체 물의 용적의 2%에 지나지 않는다. 한국의 연평균 강수량은 1,274mm로서 세계 연평균 강수량인 970mm보다 많은 편이나 인구 1인당 연간 강수량은 약 3,000m3으로서 세계 평균인 34,000m3의 11분의 1에 지나지 않는다. 수자원총량중 지하침투와 증발에 의해 손실되는 양을 제외한 하천유출량은 전체의 55%인 697억m3으로서 이것이 곧 가용수자원량이다. 그러나 하절기 강우집중도가 높은 우리나라 실정에서는 가용수자뭔량중 수자원총량의 37%가 홍수시 유출되고 실제 이용량은 수자원총량의 18%인 230억m3에 불과하여 인구증가와 함께 수자원의 가치가 더욱 증대하고 있는 실정이다. 더우기 지하수 이용량은 19억m3에 불과함에 따라 우리나라는 실제 이응수자 원량의 90% 이상을 지표수에 의존하고 있으며, 그 중 약 40%가 호소수로 구성되어 있다. 이러한 수자원 이용효율의 취약성으로 인해 제한된 수자원 용량과 생활 및 농공용수의 과수요에 따른 불균형으로 근래 많은 하천이 갈수기나 평수기시 친천화되어 가고 있어 수중생태계에 큰 위협을 주고 있다. 또한 이에 더하여 산업발달과 함께 수질오염원은 양적으로는 물론 질적으로도 증가일로에 있어 기존의 유기 및 중금속 오염물질을 포함해 수많은 신생 유기화합물질이 수계에 유출되고 있으며, 이에 더해 질소 및 인으로 대표되는 영양물질의 유입과다로 국내 대다수의 호수가 부영양화의 새로운 위협에 직 면해 있다. 우리나라에는 적은 유입유량에 큰 저수용량 및 긴 체류시간으로 대표되는 대규모 자연호는 없으며, 대부분이 매단위 강을 막아 형성된 체류시간 1년 이하의 인공호로서 그 중 안동호, 충주호, 대청호 등은 비교적 체류시간이 긴 호소형 인공호로, 팔당호나 기타 대부분의 호수는 체류시간이 짧은 하천형 인공호로 대별된다(Table 1). 이처럼 국내 호소는 국외의 자연 호와는 다른 구조적 특성을 가짐에 따라 부영양화 특성 역시 매우 상이하고, 호소형 인공호와 하천형 인공호간의 차이 역시 현저하여 일률적인 관리대책을 설정하기가 어려운 실정에 있다. 또한 각 호수의 유역특성이 상이함에 따라 호수별로 유역 오염원의 오염부하율이 현저히 달라(Table 2) 호수에 따른 특성적인 유역관리(Lake-specific management)가 요구되고 있다 정상상태(Steady state)가 아닌 국내 호소에 대해 국외 자연호의 인단순모델 (Simple phosphorus budget model)을 그대로 적용하는 것에 다소 무리한 점이 따르나, 평균적인 개념으로 OECD의 유역부하량 및 호소특성에 따른 부영양화 판정모델을 적용한다면, 국내 주요 호수는 모두 부영양 수준에 있다. 또 각 호수별로 부영양화 제어를 위해 요구되는 인의 삭감부하량은 상당량이 되어 현실적으로 관리가 이미 어려운 실정에 와 있다. 호수의 부영양화는 조류 발생으로 이어지며, 그에 따른 폐해는 각종 형태로 나타나는데 대표적으로 이취미 발생이나 유해조류에 의한 독성물질의 배출, 정수처리 과정의 THM 발생등이 주로 문제가 되고 있다. 따라서 국내 호수의 구조적 특성별 부영양화 실태를 파악하고 그에 따른 영향 및 관리방안에 관한 종합적 고찰이 차후 수질관리를 위해 요구되고 있으며, 특히 납조류로 대표되는 유해조류의 독성영향에 관한 연구는 시급한 실정에 있다.

• Journal of Korea Water Resources Association
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• v.35 no.4 s.129
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• pp.397-410
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• 2002

In order to quantitatively identify historical drought conditions and to evaluate their variability, drought indices commonly used. The calculation method for the drought index based on the principal hydrological factors, such as precipitation and reservoir storage, can estimate the duration and intensity of a drought. In this study the Palmer-type formula for drought index is derived for the Nakdong River basin by analyzing the monthly rainfall and meteorological data at 21 stations. The Palmer Drought Severity Index(PDSI) is used for dry land sectors to evaluate the meteorological anomaly in terms of an index which permits time and space comparisons of drought severity. The Surface Water Supply Index(SWSI) is devised for the use in conjunction with the Palmer index to provide an objective indicator of water supply conditions in Nakdong River basin. The SWSI was designed to quantify surface water supply capability of a watershed which depends on river and reservoir water The Standardized Precipitation Index(SPI) is evaluated for various time periods of 1 to 12 months in Nakdong River basin. For the purpose of comparison between drought indices correlation coefficient was calculated between indices and appropriate SPI time period was selected as 10 months for Nakdong River basin. A comparative study is made to evaluate the relative severity of the significant droughts occurred in Nakdong River basin since 1976. It turned out that $'94{\sim}'97$ drought was the worst drought in it's severity. It is found that drought indices are very useful tools in quantitatively evaluating the severity of a drought over a river basin.

• Journal of Wetlands Research
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• v.15 no.3
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• pp.367-380
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• 2013

In this study, sub-indicators, and thematic mid-indexes to evaluate the water use characteristics were selected through historical data analysis and factor analysis, and consisted of the subject approach framework. And the integrated index was developed to evaluate water use characteristics of the watershed. Using developed index, the water use characteristics were assessed for 812 standard basins with the exception for North Korea using data of 1990 to 2007 from the relevant agencies. A sensitivity analysis is conducted for this study to determine the proper way through various normalization and weighting methods. To increase the objectivity of developed index, the history of the damage indicators are excluded in the analysis. In addition, in order to ensure its reliability, results from index with and without consideration of the damage history were compared. Also, the index is also applied to real data for 2008 Gangwon region to verify its field applicability. Through the validation process this index confirmed the adequacy for the indicators selection and calculation method. The results of this study were analyzed based on the spatial and time vulnerability of the basin's water use, which can be applied to various parts such as priority decision-making for water business or policy, mitigations for the vulnerable components of the basin, and supporting measures to establishment by providing relevant information about it.

• Journal of Wetlands Research
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• v.21 no.1
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• pp.9-15
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• 2019

The Daegi-cheon watershed is located in the upper part of the Han River, which has the representative highland vegetable growing complexes. This watershed has a large impact on the water quality and aquatic ecosystem in the upstream of the Han River by discharging a large amount of turbid water during rainfall season. For proposing an efficient turbid water management and policy, the analysis of the characteristics of flow rate and SS and its causes needs to be carried out preferentially. In this study, the relationship between flow rate and SS concentration was analyzed in the Daegi-cheon watershed, and in turn the turbidity characteristics were analyzed. As a result of the study, in the normal flood flow condition, it was shown that SS concentration changed arbitrarily due to various environmental factors. On the other hand, the SS concentration was considerably high in the very high flow condition. Based on the field survey, this could be the reason why the effects of the steep valley and slope collapse according to the very high flow rate as well as the source in the agricultural fields were greatly contributed. Therefore, it is necessary to develop a structural best management practice that can stabilize the steep slope and reduce river bed loss along with the typical source managements plans.

• The Journal of Engineering Geology
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• v.28 no.4
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• pp.541-552
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• 2018

The implementation of drought measures in the upstream areas of river basins is seldom considered with respect to water supply. However, the demand for such measures is increasing rapidly owing to the occurrence of severe droughts, and interventions on streams and the water supply are needed. Physical interventions are an option to prevent streams from becoming dry and to maintain stream water flow, but dam construction is challenging because of environmental and ecological considerations. Here, a feasibility study was conducted to assess the potential effects of sand dams, which are widely used in arid regions in Africa. The SWAT-K model, which is a hydrologic model used for Korean watersheds, is used to estimate the flow rate of water in an ungauged watershed. The changes in water storage of the sand-dammed reservoir and in downstream flow rates are estimated for two types of sand dam (natural and dredged). The results show that sand dams are capable of increasing the downstream flow rate during normal conditions and of mitigating water supply problems caused by the withdrawal of water during drought periods.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.248-248
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• 2018

새만금 종합개발계획(정부, 2011)에 따른 내부개발의 완료시점은 2030년이며, 방수제 공사와 준설 등과 같이 만경강 및 동진강 유역 내 흐름을 변화시킬 수 있는 공사를 포함하고 있으므로 현재와 2030년의 하천 및 호의 수리특성은 다를 것이라 예상된다. 2030년까지 준설상황 등을 예측하여 반영하는 것은 사실상 불가능하기 때문에 새만금 종합개발계획에서 제시하고 있는 내부개발의 완료시점을 기준으로 홍수사상을 모의하였다. 새만금 호의 물리적인 변화는 수리특성의 변화로 이어질 수 있으며, 이는 상류지역으로 전파가 될 수 있으므로 호내 뿐만 아니라 만경강과 동진강 전역에 대한 홍수시의 수리특성을 검토하였다. 새만금 호와 연결된 만경강과 동진강의 설계홍수량은 대부분의 구간에서 100년 빈도이기 때문에 본 연구에서는 100년 빈도 홍수사상에 대한 분석을 기초로 홍수위 검토를 수행하였고, RCP8.5 시나리오를 적용한 100년 빈도 홍수량과 500년 빈도 홍수량에 대한 추가적인 연구를 수행하였으며, 이 결과를 토대로 취약지구 분석 및 대책 등을 제시하였다. 수치모의는 Delft3D를 이용하였으며, 새만금 유역의 동진강 지구의 실측치와 비교함으로써 모델의 적용성을 검증하였다. 서해안 조위 특성상 새만금 방조제는 조위 영향이 크므로, 이에 본 연구에서는 외조위의 특성을 고려하기 위해 새만금 유역 주변의 12개 조화상수(tidal harmonic constant)를 이용하여 조위에 대한 모의를 별도로 수행하고, 이 결과를 배수갑문의 경계조건으로 이용하였다. 상류 경계조건은 하천기본계획상에 제시된 하천은 이를 이용하였으며, 그 외의 소하천은 유역면적을 이용한 계산법을 사용하여, 선형적 면적 비유량(Specific Discharge, SD) 방법을 적용하여 본류의 유량에 부가하는 방식으로 수행하였다. 수치해석 결과, 준설 구간의 수위는 전반적으로 저하되었으며, 거리에 따른 수면의 경사를 분석한 결과 기존의 하천구역이 준설 등으로 인하여 호수의 특성으로 변화된 것으로 확인하였다. 본 연구에서 취약지구는 홍수위가 제방고의 약 80% 이상 되는 지역으로 결정하였으며, 이를 토대로 취약지구 분석을 수행한 결과 기존 100년 빈도에서 1지점, RCP 8.5 시나리오가 적용된 100년 빈도에서 88지점, 500년 빈도에서 125지점이 잠재적인 치수 위험이 있는 것으로 파악되었다. 기존의 1차원 연구결과와는 차이가 있는 부분은, 다수의 취약지구가 만곡부 또는 합류부 인근에 위치한 것이다. 향후 이러한 상대적인 치수 취약지점에 대해 정밀하고 국부적인 연구를 수행하여 정확한 홍수위 예측을 수행해야 할 것이다.

• Korean Journal of Environment and Ecology
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• v.38 no.2
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• pp.178-188
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• 2024

The dynamics of suspended sediment (SS) in forested catchments vary depending upon human or natural disturbances, including land use change, forestry activity, forest fires, and landslides. Understanding the dynamics of SS originating from the potential sources within a forested catchment is crucial for establishing an effective water quality management strategy. Therefore, to suggest a systematic method for interpreting SS dynamics, we evaluated the performance and applicability of ten methods for calculating the hysteresis index based on observed hydrological data and two calculation models (Lawler's method and Lloyd's method) with five sampling intervals (50th, 25th, 10th, 5th, and 1st percentiles). Our results showed that Lloyd's method, which used a sampling interval at the 1st percentile, had the largest number of analyzable runoff events and exhibited the best performance. The results of this study can contribute to quantifying the hysteresis in the relationship between discharge and SS and provide useful information for interpreting SS dynamics.

• Journal of Korea Water Resources Association
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• v.41 no.3
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• pp.277-291
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• 2008

In order to carry out river basin management, it is necessary to evaluate the state of the river basin and make site-specific measures on the basis of management goals and objectives. A river basin is divided into several watersheds, which are composed of several components: water resources, social and economic systems, law and institution, user, land, ecosystems, etc. They are connected among them and form network holistically. In this study, a methodology for evaluating watershed management was developed by consideration of the various features of a watershed system. This methodology employed factor analysis to develop sub-indexes for evaluating water use management, environment and ecosystem management, and flood management in a watershed. To do this, first, the related data were gathered and classified into six groups that are the components of watershed systems. Second, in all sub-indexes, preliminary tests such as KMO (Kaiser-Meyer-Olkin) measure of sampling adequacy and Bartlett's test of sphericity were conducted to check the data's acceptability to factor analysis, respectively. Third, variables related to each sub-index were grouped into three factors by consideration of statistic characteristics, respectively. These factors became indicators and were named, taking into account the relationship and the characteristics of included variables. In order to check the study results, the computed factor loadings of each variable were reviewed, and correlation analysis among factor scores was fulfilled. It was revealed that each factor score of factors in a sub-index was not correlated, and grouping variables by factor analysis was appropriate. And, it was thought that this indicator system would be applied effectively to evaluating the states of watershed management.

• Korean Journal of Ecology and Environment
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• v.42 no.2
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• pp.200-211
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• 2009

A mathematical modeling program called Soil and Water Assessment Tool (SWAT) developed by USDA was applied to Kyongan stream watershed. It was run under BASINS (Better Assessment Science for Integrating point and Non-point Sources) program, and the model was calibrated and validated using KTMDL monitoring data of 2004${\sim}$2008. The model efficiency of flow ranged from very good to fair in comparison between simulated and observed data and it was good in the water quality parameters like flow range. The model reliability and performance were within the expectation considering complexity of the watershed and pollutant sources. The results of pollutant loads estimation as yearly (2004${\sim}$2008), pollutant loadings from 2006 were higher than rest of year caused by high precipitation and flow. Average non-point source (NPS) pollution rates were 30.4%, 45.3%, 28.1% for SS, TN and TP respectably. The NPS pollutant loading for SS, TN and TP during the monsoon rainy season (June to September) was about 61.8${\sim}$88.7% of total NPS pollutant loading, and flow volume was also in a similar range. SS concentration depended on precipitation and pollution loading patterns, but TN and TP concentration was not necessarily high during the rainy season, and showed a decreasing trend with increasing water flow. SWAT based on BASINS was applied to the Kyongan stream watershed successfully without difficulty, and it was found that the model could be used conveniently to assess watershed characteristics and to estimate pollutant loading including point and non-point sources in watershed scale.