• 물과 미래
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• 제45권2호
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• pp.93-102
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• 2012

• 한국관개배수논문집
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• 제13권2호
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• pp.303-309
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• 2006

• 한국습지학회지
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• 제16권2호
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• pp.161-171
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• 2014

수문곡선의 감수부는 기저유출의 특성을 반영하기 때문에 강우유출 모형과 기저유출분리법을 이용한 기저유출 산정과정에서 감수부의 특성을 고려해야한다. 따라서 본 연구는 감수특성을 고려하여 Soil and Water Assessment Tool(SWAT)의 보정에서 유량예측의 정확성을 높이고, 보정된 SWAT으로부터 예측된 유량으로부터 기저유출을 분리하고자 하였다. 이를 위하여 RECESS으로부터 산정된 alpha factor와 11개의 다른 매개변수를 자동보정모듈에 적용한 시나리오 (S1)와 SWAT의 매개변수인 alpha factor를 포함한 12개의 매개변수를 자동보정모듈에 적용한 시나리오 (S2)에 대해 SWAT을 이용해 유량 모의를 하였다. 또한, 두 시나리오에 대해 SWAT으로 예측된 유량을 Web-based Hydrograph Analysis Tool (WHAT)을 적용하여 기저유출을 산정하였다. 보정 결과는 유량에 대한 두 시나리오의 Nash-Sutcliffe Efficiency (NSE) 값들 사이에 큰 차이는 보이지 않았으나 기저유출의 경우 S1에 대한 NSE는 0.777이고, S2의 NSE 결과는 0.844로 다소 큰 차이를 보였다. 연평균 유량의 분포의 정량적 비교를 위한 관측유량과 상대오차를 산정하였으며 S1에 대하여 20.78%, S2에 대하여 6.59%의 상대오차를 보였다. 본 연구는 모형을 이용하여 예측된 유량으로부터 기저유출을 산정하는데 있어 감수부 특성의 중요성을 보여주었다.

• 한국농공학회논문집
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• 제59권6호
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• pp.101-108
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• 2017

This study attempted to improve the accuracy of streamflow and baseflow prediction of Soil and Water Assessment Tool (SWAT) by applying baselfow recession constants for each sub-watershed. This study set two different scenarios (S1 and S2) to evaluate the impact of application of baseflow recession constants for each sub-watershed on streamflow prediction. In S1, Only the baseflow recession constant obtained from the streamflow station located in the final outlet of study area was applied for whole sub-watersheds. In S2, baseflow recession constants obtained from six different streamflow stations were applied for each sub-watershed. Then, baseflow was separated form the measured streamflow data and the predicted streamflow of S1 and S2 using Web-based Hydrograph Analysis Tool (WHAT). The results showed Nash-Sutcliff efficiency (NSE) and $R^2$ of S2 were a little higher than these of S1 in both streamflow and baseflow prediction results. However, it is important that S2 reflected physical meaning of baseflow recess. Also, recession part of hydrograph in S2 was calibrated better than that of S1 compared to the measured hydrograph.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2011년도 학술발표회
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• pp.375-375
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• 2011

유역에서 강우에 따라 유출이 발생하면 지표면을 따라 하천으로 유입되거나, 땅속으로 침투하여 깊은 대수층으로 유입되던지 기저유출 형태로 하천으로 유입된다. 이렇듯 하천을 구성하는 중요 두 가지 요소인 직접유출량과 기저유출량을 정확히 산정하는 것이 유역 수자원관리 및 비점오염원 관리에 매우 중요한 부분이라 할 수 있다. 그동안 하천에서 측정된 유출량에서 직접유출과 기저유출을 분리하기 위한 많은 연구가 진행되어 왔으며, 최근에는 주관적인 면을 배제하고 장기실측 유량자료를 이용하여 기저유출을 분리할 수 있는 BFlow, HYSEP, PART, RORA, RECESS, 디지털 필터링 모형 등 많은 프로그램들이 개발되어 활용되어 오고 있다. 또한 최근에는 인터넷을 통해 활용할 수 있는 Web 기반 WHAT 프로그램이 개발되어 전 세계적으로 널리 활용되고 있다. 이에 본 연구에서는 XML 프로그래밍 기법을 이용하여 WHAT 프로그램을 확장한 Expaned XML-based WHAT (EX-WHAT) 시스템 (http://www.EnvSys.co.kr/~exwhat)을 개발 하였다. 기존의 시스템에서는 USGS 일유량자료를 URL을 통해 WHAT 서버에 저장한 후 이를 가공하여 수문 분석을 수행하였으나, 이번 연구를 통해서 개발된 시스템은 XML/Parser를 이용하여 USGS 서버에 저장되어 있는 일유량자료를 바로 읽어서 수문분석을 수행할 수 있게 되었다. 이 EXWHAT 시스템에는 BFlow, HYSEP, PART, Digital Filters 와 같은 엔진이 사용되고 있다. 본 연구에서 개발된 EX-WHAT 분석결과는 XML 형식으로 제공되고 있기 때문에, 다른 Web/Desktop 기반의 관련 프로그램에서 바로 활용될 수 있을 것이라 판단된다. 특히 EX-WHAT 분석결과는 유역관리, 기저유출을 통한 비점오염원 관리 평가, 지속가능한 지하수 고나리 등 다양한 수문/비점오염 연구/실무에 활용될 수 있을 것이라 판단된다.

• 한국물환경학회지
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• 제22권2호
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• pp.244-249
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• 2006

Natural environment of Weolgokri watershed has been well preserved as a traditional agricultural watershed. A year record of streamflow, $NO_3-N$, T-N and T-P concentrations data (April 2004 - Mar. 2005) were examined to estimate annual and seasonal patterns of pollutant loads in streamflow and baseflow from the agricultural watershed. To estimate pollutant loads from baseflow, baseflow component was separated from streamflow using the digital filter method in the Web-based Hydrograph Analysis Tool system and loads of $NO_3-N$, T-N and T-P from streamflow and baseflow were evaluated. The $NO_3-N$, T-N, and T-P loads from streamflow were 13.85 kg/ha, 45.92 kg/ha and 1.887 kg/ha, respectively, while corresponding loads from baseflow were 7.43 kg/ha, 24.70 kg/ha, 0.582 kg/ha, respectively. It was found that $NO_3-N$ and T-N loads were contributed slightly more by the baseflow (53% and 53% of Total-loads) than by the direct runoff (47% and 47% of Total loads). However, only 30% of total T-P load was contributed by the baseflow. It is recommended that one needs to assess pollutant load contribution by the baseflow to identify appropriate pollution control strategies for an effective watershed management.

• 한국물환경학회지
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• 제23권6호
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• pp.897-905
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• 2007

Approximately 70% of Korea is composed of forest areas. Especially 48% of agricultural field is practiced at highland areas over 400 m in elevation in Kangwon province. Over 90% of highland agricultural farming is located at Kangwon province. Runoff characteristics at the mountainous area such as Kangwon province are largely affected by steep slopes, thus runoff estimation considering field slopes needs to be utilized for accurate estimation of direct runoff. Although many methods for runoff estimation are available, the Soil Conservation Service (SCS), now Natural Resource Conservation Service (NRCS), Curve Number (CN)-based method is used in this study. The CN values were obtained from many plot-years dataset obtained from mid-west areas of the United States, where most of the areas have less than 5% in slopes. Thus, the CN method is not suitable for accurate runoff estimation where significant areas are over 5% in slopes. Therefore, the CN values were adjusted based on the average slopes (25.8% at Doam-dam watershed) depending on the 5-day Antecedent Moisture Condition (AMC). In this study, the CN-based Long-Term Hydrologic Impact Assessment (L-THIA) direct runoff estimation model used and the Web-based Hydrograph Analysis Tool (WHAT) was used for direct runoff separation from the stream flow data. The $R^2$ value was 0.65 and the Nash-Sutcliffe coefficient value was 0.60 when no slope adjustment was made in CN method. However, the $R^2$ value was 0.69 and the Nash-Sutcliffe value was 0.69 with slope adjustment. As shown in this study, it is strongly recommended the slope adjustment in the CN direct runoff estimation should be made for accurate direct runoff prediction using the CN-based L-THIA model when applied to steep mountainous areas.

• 한국물환경학회지
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• 제27권4호
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• pp.405-412
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• 2011

Increased Non-permeable areas which have resulted from civilization reduce the volume of groundwater infiltration that is one of the important factors causing water shortage during a dry season. Thus, seeking the efficient method to analyze the volume of groundwater in accurate should be needed to solve water shortage problems. In this study, two different watersheds were selected and precipitation, soil group, and land use were surveyed in a particular year in order to figure out the accuracy of estimated infiltration recharge ratio compared to Web-based Hydrograph Analysis Tool (WHAT). The volume of groundwater was estimated considering Antecedent soil Moisture Condition (AMC) and Curve Number (CN) using Long Term Hydrologic Impact Assessment (L-THIA) model. The results of this study showed that in the case of Kyoung-an watershed, the volume of both infiltration and baseflow seperated from WHAT was 46.99% in 2006 and 33.68% in 2007 each and in Do-am watershed the volume of both infiltration and baseflow was 33.48% in 2004 and 23.65% in 2005 respectively. L-THIA requires only simple data (i.e., land uses, soils, and precipitation) to simulate the accurate volume of groundwater. Therefore, with convenient way of L-THIA, researchers can manage watershed more effectively than doing it with other models. L-THIA has limitations that it neglects the contributions of snowfall to precipitation. So, to estimate more accurate assessment of the long term hydrological impacts including groundwater with L-THIA, further researches about snowfall data in winter should be considered.

• 한국농공학회논문집
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• 제52권1호
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• pp.1-11
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• 2010

Generation and transportation of runoff and pollutant loads within watershed generated eutrophication at Daecheong reservoir. To improve water quality at Daecheong reservoir, the best management practices should be developed and applied at upper watersheds for water quality improvement at downstream areas. In this study, two small watersheds of upper Daecheong reservoir were selected. The Long-Term Hydrologic Impact Assessment (L-THIA) model has been widely used for the estimation of the direct runoff worldwide. To apply the L-THIA ArcView GIS model was evaluated for direct runoff and water quality estimation at small watershed. And the Web-based Hydrograph Analysis Tool (WHAT) was used for direct runoff separating from total flow. As a result, the $R^2$ (Coefficient of determination) value and Nash-Sutcliffe coefficient value for direct runoff comparison at An-nae watershed were 0.81 and 0.71, respectively. And the $R^2$ value and Nash-Sutcliffe coefficient value at Wol-oe were 0.95 and 0.93. The $R^2$ value of BOD, TOC, T-N and T-P at An-nae watershed were BOD 0.94, TOC 0.81, T-N 0.94 and T-P 0.89. And the $R^2$ value of BOD, TOC, T-N and T-P at Wol-oe watershed were BOD 0.80, TOC 0.93, T-N 0.86 and T-P 0.65. The result that estimated pollutant loadings using the L-THIA ArcView GIS model reflected well the measured pollutant loadings except for T-P in Wol-oe watershed. With L-THIA ArcView GIS model, the direct runoff and non-point pollutant (NPS) loadings in the watershed could be analyzed through simple input data such as daily rainfall, land uses, and hydrologic soil group.

• 한국물환경학회지
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• 제23권4호
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• pp.474-481
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• 2007

With population growth, industrialization, and urbanization within the watershed, the hydrologic response changed dramatically, resulting in increases in peak flow with lesser time to peak and total runoff with shortened time of concentration. Infiltration is directly affected by initial soil moisture condition, which is a key element to determine runoff. Influence of the initial soil moisture condition on hydrograph analysis should be evaluated to assess land use change impacts on runoff and non-point source pollution characteristics. The Long-Term Hydrologic Impact Assessment (L-THIA) model has been widely used for the estimation of the direct runoff worldwide. The L-THIA model was applied to the Little Eagle Creek (LEC) watershed and Its estimated direct runoff values were compared with the BFLOW filtered direct runoff values by other researchers. The $R^2$ value Was 0.68 and the Nash-Sutcliffe coefficient value was 0.64. Also, the L-THIA estimates were compared with those separated using optimized $BFI_{max}$ value for the Eckhardt filter. The $R^2$ value and the Nash-Sutcliffe coefficient value were 0.66 and 0.63, respectively. Although these higher statistics could indicate that the L-THIA model is good in estimating the direct runoff reasonably well, the Antecedent Moisture Condition (AMC) was not adjusted in that study, which might be responsible for mismatches in peak flow between the L-THIA estimated and the measured peak values. In this study, the L-THIA model was run with AMC adjustment for direct runoff estimation. The $R^2$ value was 0.80 and the Nash-Sutcliffe coefficient value was 0.78 for the comparison of L-THIA simulated direct runoff with the filtered direct runoff. However there was 42.44% differences in the L-THIA estimated direct runoff and filtered direct runoff. This can be explained in that about 80% of the simulation period is classified as 'AMC I' condition, which caused lower CN values and lower direct runoff estimation. Thus, the coefficients of the equation to adjust CN II to CN I and CN III depending on AMC condition were modified to minimize adjustments impacts on runoff estimation. The $R^2$ and the Nash-Sutcliffe coefficient values increase, 0.80 and 0.80 respectively. The difference in the estimated and filtered direct runoff decreased from 42.44% to 7.99%. The results obtained in this study indicate the AMC needs to be considered for accurate direct runoff estimation using the L-THIA model. Also, more researches are needed for realistic adjustment of the AMC in the L-THIA model.