• 한국농공학회논문집
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• 제60권5호
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• pp.81-93
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• 2018

The Kajiyama formula, which is an empirical formula based on the maximum flood data at Korean watersheds, has been widely used for the design of hydraulic structures and management of watersheds. However, this formula was developed based on meteorological data and flow measured during early 1900s so that it could not consider the recently changed rainfall pattern due to climate changes. Moreover, the formula does not provide the monthly coefficients for 5 months including July and August (flood season), which causes the uncertainty to accurately interpret runoff characteristics at a watershed. Thus, the objective of this study is to enhance the monthly coefficients based on the recent meteorological data and flow data expanding the range of rainfall classification. The simulated runoff using the enhanced monthly coefficients showed better performance compared to that using the original coefficients. In addition, we evaluated the applicability of the enhanced monthly coefficient for future runoff prediction. Based on the results of this study, we found that the Kajiyame formula with the enhanced coefficients could be applied for the future prediction. Hence, the Kajiyama formula with enhanced monthly coefficient can be useful to support the policy and plan related to management of watersheds in Korea.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2012년도 학술발표회
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• pp.1-10
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• 2012

Throughout much of the world, many ecological problems have arisen in watersheds where a significant portion of stream flows are diverted to support agriculture production. Within endorheic watersheds (watersheds whose terminus is a terminal lake) these problems are magnified due to the cumulative effect that reduced stream flows have on the condition of the lake at the stream's terminus. Within an endorheic watershed, any diversion of stream flows will cause an imbalance in the terminal lake's water balance, causing the lake to transition to a new equilibrium level that has a smaller volume and surface area. However, the total mass of Total Dissolved Solids within the lake will continue to grow; resulting in a significant increase in the lake's TDS concentration over time. The ecological consequences of increased TDS concentrations can be as limited as the intermittent disruption of productive fisheries, or as drastic as a complete collapse of a lake's ecosystem. A watershed where increasing TDS concentrations have reached critical levels is the Walker Lake watershed, located on the eastern slope of the central Sierra Nevada range in Nevada, USA. The watershed has an area of 10,400 sq. km, with average annual headwater flows and stream flow diversions of 376 million $m^3/yr$ and 370 million $m^3/yr$, respectively. These diversions have resulted in the volume of Walker Lake decreasing from 11.1 billion m3 in 1882 to less than 2.0 billion $m^3$ at the present time. The resulting rise in TDS concentration has been from 2,560 mg/l in 1882 to nearly 15,000 mg/l at the current time. Changes in water management practices over the last century, as well as climate change, have contributed to this problem in varying degrees. These changes include the construction of reservoirs in the 1920s, the pumpage of shallow groundwater for irrigation in the 1960s and the implementation of high efficiency agricultural practices in the 1980s. This paper will examine the impacts that each of these actions, along with changes in the region's climate, has had on stream flow in the Walker River, and ultimately the TDS concentration in Walker Lake.

• 한국수자원학회논문집
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• 제30권5호
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• pp.423-430
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• 1997

수자원개발 계획과 설계를 위한 설계홍수량 추정에 가장 중요한 문제의 하나가 유효우량 추정이다. 우리나라 수공구조물의 설계홍수량 추정에는 미국 SCS에서 개발한 유출곡선번호(curve number)로부터 유효우량을 추정하고 홍수도달시간을 고려하여 단위도를 합성하는 방법이 자주 사용되고 있다. 그러나, 우리나라의 경우 시간별 강우-유출량 자료가 충분하지 못한 상태이므로 SCS 유출곡선번호 방법을 그대로 적용하여 유효우량을 추정할 때에는 신중을 기해야 한다. 왜냐하면 우리나라의 토양, 식생 토지이용, 배수조건 등의 유출특성이 미국 유역의 유출특성과 다르고 특히 논이라는 독특한 토이이용형태가 13%나 차지하고 있기 때문이다. 이에 본 연구에서는 유역이 가장 건조한 상태의 유출곡선번호 CN-I을 SCS 유출곡선번호에서 구하지 않고 강우-유출모형인 DAWAST(DAily WAtershed STreamflow, 김태철, 1992) 모형의 유역 최대잠재저류능인 Umax로부터 구하는 방법을 제시하였다. 이매개변수 Umax는 우리나라 유역에서 관측된 일별 강우-유출량 자료를 최적화 기법으로 보정하여 구했으므로 이로부터 추정된 유출곡선번호는 우리나라의 유역특성이 반영되었다고 볼 수 있다.

• 한국물환경학회지
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• 제32권2호
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• pp.149-162
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• 2016

In recent years, there has been demand for precise estimations of pollutant loads on nationwide scale for the development of appropriate site specific (watershed specific) policies to reduce the negative impact of pollutant loads. River flow data and water quality data that were previously collected by various research institutes and universities for specific research purposes for a limited period was utilized in this study. However, only TMDL 8-day interval flow and water quality data were available in national scale. Three watersheds were selected and pollutant loads were calculated by two methods i.e., Numeric Integration (NI) method and Soil and Water Assessment Tool (SWAT). Subsequently, the results were compared to determine the appropriate method for monitoring nonpoint source networks nationwide. The SWAT model was calibrated and its estimated daily flow data were used in the NI method with estimated sediment data for 8-day monitoring data for three watersheds. The results indicated that the quantity of pollutant loads estimated with the NI and SWAT are different to some degrees especially during the summer season for all the three study watersheds. Thus, more frequent sampling of water quality is needed for nonpoint source pollutant estimation.

• 한국물환경학회지
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• 제27권4호
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• pp.509-515
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• 2011

For this study the 4 sub-watersheds Okdong A, Hankang B, Jecheon A and Hankang C which are the main streams of the Han River within the mid-level region of Chungju Dam are selected and the analysis of soils has been carried out through the soil basic survey. When it comes to the soil erosion amount the soil nutrient load has been calculated by utilizing the RUSLE erosion equation. In case of the data related to the measurement of water flow and quality the information available from the "Water Information System" one of the websites run by the Ministry of Environment has been used to calculate the water pollution load. The correlation between the soil nutrient load and the water pollutant load has been analyzed through making comparison. According to the results related to the soil nutrient load of each sub-watershed the Hankang C shows the highest values TOC 29,986.92 ton/yr, TN 3,860.33 ton/yr and TP 973.97 ton/yr respectively. Even when it comes to the loads related to water quality the Hankang C shows also comparatively high values TOC 6,625.64 ton/yr, TN 7,335.01 ton/yrand TP 145.49 ton/yr respectively. The soil nutrient loads of the sub-watersheds are shown to increase towards the lower stream meaning the load increases in the order of Hankang CHankang B and Okdong A. When it comes to the water pollutant load the value goes up along down the water system meaning the load gets higher in the order of Hankang C, Hankang B and Okdong A while utilizing the mainstream within the mid-level region of Chungju Dam as the basis. The correlation study showed that the nutrient content of soil is proportional to the pollutant load in water with the strongest positive correlation with TOC.

• 한국물환경학회지
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• 제36권6호
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• pp.489-499
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• 2020

Effective science-based management of the basin water resources requires an understanding of the characteristics of the streams, such as the baseflow discharge. In this study, the base flow was estimated in the two watersheds with the least artificial factors among the Nakdong River watersheds, as determined using the chemical hydrograph separation technique. The 16-year (2004-2019) discontinuous observed stream flow and electrical conductivity data in the Total Maximum Daily Load (TMDL) monitoring network were extended to continuous daily data using the TANK model and the 7-parameter log-linear model combined with the minimum variance unbiased estimator. The annual base flows at the upper Namgang Dam basin and the upper Nakdong River basin were both analyzed to be about 56% of the total annual flow. The monthly base flow ratio showed a high monthly deviation, as it was found to be higher than 0.9 in the dry season and about 0.46 in the rainy season. This is in line with the prevailing common sense notion that in winter, most of the stream flow is base flow, due to the characteristics of the dry season winter in Korea. It is expected that the chemical-based hydrological separation technique involving TANK and the 7-parameter log-linear models used in this study can help quantify the base flow required for systematic watershed water environment management.

• 한국물환경학회지
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• 제40권2호
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• pp.67-78
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• 2024

The introduction of a significant amount of phosphorous into aquatic environments can lead to eutrophication, which can in turn result in algal blooms. For the effective management of watersheds and the prevention of water quality problems related to nonpoint organic matter (OM) sources, it is essential to pinpoint the predominant OM sources. Several potential OM sources were sampled from upper agricultural watersheds, such as fallen leaves, riparian reeds, riparian plants, paddy soil, field soil, riparian soil, cow manure, and swine manure. Stream samples were collected during two storm events, and the concentrations of dissolved organic carbon (DOC) and phosphorous (DOP) from these OM sources and stream samples were assessed. DOM indicators using fluorescence spectroscopy, including HIX, FI, BIX, and EEM-PARAFAC, were evaluated in terms of their relevance in discerning DOM sources during storm events. Representative DOM descriptors were chosen based on specific criteria, such as value ranges and pronounced differences between low and high-flow periods. Consequently, the spectral slope ratio (S_R) paired with fluorescence index (FI) using end-member mixing analysis (EMMA) proved to be suitable for estimating the contribution of organic carbon (OC). The contribution of each organic phosphorous (OP) in stream samples was determined using the phosphorous-to-carbon (P/C) ratio in conjunction with the OC contribution. Notably, OP derived from swine manure in stream samples was found to make the most dominant contribution, ranging from 61.3% to 94.2% (average 78.1% ± 12.7%). The results of this research offer valuable insights into the selection of suitable indicators to recognize various OM sources and highlight the main sources of OP in forested-agricultural watersheds.

• 한국지리정보학회지
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• 제8권2호
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• pp.145-156
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• 2005

파편화와 같은 인위적 교란은 산림생태계의 지속성에 영향을 미치므로, 산림의 양적인 분포뿐만 아니라 구조적인 패턴을 분석하는 것은 산림생태계를 관리하는 기본적인 과정이라 할 수 있다. 이에 본 연구에서는 산림생태계의 건전성 평가 및 관리계획 수립을 위한 기초정보를 제공하기 위해 경관지수와 GIS 기법을 활용하여 낙동강 유역에 분포하는 산림구조를 정량적으로 분석하였다. 분석에 필요한 공간정보는 환경부에서 발행한 토지피복분류도를 이용하여 구축하였으며, 경관지수 상호간 정보의 중복을 배제하기 위하여 Pearson 상관분석을 통해 6개의 지수(LPI, PD, ED, MSI, CPLAND, IJI)를 선정하였다. 경관지수를 이용한 산림경관의 구조적 패턴을 분석한 결과, 낙동강 본류에 분포하는 유역들에서 파편화 정도가 다른 유역에 비해 상대적으로 높게 나타났다. 특히 낙동상주 유역과 낙동밀양 유역은 산림의 양적인 측면뿐만 아니라 구조적으로도 불안정한 상황을 보이는 것으로 나타났는데, 이들 유역에 대해서는 지역의 환경조건에 부합하는 산림복원 등의 생태적 관리를 위해 현장검증 및 영향인자에 대한 추가적인 연구가 필요할 것으로 판단된다.

• 대한토목학회논문집
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• 제32권1B호
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• pp.71-78
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• 2012

서식처적합도는 어류의 서식처 분포 및 그 크기를 결정하는데 있어 매우 중요한 인자이다. 또한 어류 서식에 필요한 생태유량 산정에서도 핵심 인자로 작용된다. 따라서 서식처 해석을 위해서는 정확한 서식처적합도지수를 반영할 필요가 있다. 일반적으로 어류 서식처는 수심과 유속과 같은 물리적 조건 뿐만 아니라 영양염 및 부착조류 등의 생화학적 조건에 의해 영향을 받는다. 따라서 각 수계 및 지천별로 이러한 서식처 조건이 변화할 것으로 예상된다. 본 연구에서는 한강과 금강수계에서 지난 2007-2010년 간의 현장 모니터링 데이터를 이용하여 서식처적합도지수를 산정하고, 피라미, 참갈겨니, 쉬리에 대한 지수를 비교하였다. 그 결과, 피라미는 두 수계에서 서로 유사한 분포를 갖지만, 참결겨니와 쉬리의 경우 두 수계에서 매우 다른 분포 형태를 갖는 것으로 나타났다. 또한 피라미에 대하여 한강 지천인 청미천, 달천, 홍천강에서의 적합도지수를 비교하였다. 그 결과 청미천에서의 적합도지수가 다른 두 지천과 매우 다른 분포를 갖는 것으로 확인되었으며, 이는 청미천이 다른 지천에 비해 영양염의 유입이 더 크기 때문인 것으로 예상된다.

• Current Research on Agriculture and Life Sciences
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• 제10권
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• pp.35-40
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• 1992

전국(全國) 112개(個) 저수지(貯水池)를 대상(對象)으로 유성인자간(流城因子間)의 관계(關係) 및 유성인자(流城因子)와 첨두유량(尖頭流量)과의 관계(關係)를 조사(調査) 분석(分析)한 결과(結果) 다음과 같은 결론(結論)을 얻었다. 1. 유성면적(流城面積)과 주하천장(主河川長), 유성면적(流城面積)과 유성(流城)의 주장(周長), 유성면적(流城面積)과 지류총연장(支流總延長), 주하천장(主河川長)과 유성(流城)의 주장(周長), 주하천장(主河川長)과 하천중심장(河川重心長), 주하천(主河川) 평균경사(平均傾斜)와 유성(流城)의 평균표고(平均標高)와의 관계(關係)를 상관분석(相關分析)하여 상호간(相互間)의 상관관계식(相關關係式)을 유도(誘導)하였다. 2. 각 유성인자(流城因子)와 첨두류량(尖頭流量)과의 단순상관분석(單純相關分析) 결과(結果) 상관계수(相關係數) r=0.004~0.546으로 비교적(比較的) 낮게 나타나 유성(流城)으로부터의 유출현상(流出現象)은 그 유성(流城)의 여러 인자(因子)에 영향(影響)을 받는다는 것을 확인(確認)할 수 있었다. 3. 유성면적(流城面積), 주하천장(主河川長), 주하천(主河川) 평균경사(平均傾斜), 저수지(貯水池) 설치점(設置點)의 표고(標高)를 독립변수(獨立變數)로 하여 첨두유량(尖頭流量)과의 다중상관분석(多衆相關分析)을 실시(實施)한 결과(結果) $Q_{100}=66.43A^{0.869}L^{-0.536}S^{0.456}Hs^{-0.122}$인 상관식(相關式)이 유도(誘導)되었다.