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한강수계에서의 부유사 예측을 위한 LOADEST 모형의 회귀식의 평가
박윤식,이지민,정영훈,신민환,박지형,황하선,류지철,박장호,김기성,Park, Youn Shik,Lee, Ji Min,Jung, Younghun,Shin, Min Hwan,Park, Ji Hyung,Hwang, Hasun,Ryu, Jichul,Park, Jangho,Kim, Ki-Sung 한국농공학회 2015 한국농공학회논문집 Vol.57 No.2
Typically, water quality sampling takes place intermittently since sample collection and following analysis requires substantial cost and efforts. Therefore regression models (or rating curves) are often used to interpolate water quality data. LOADEST has nine regression models to estimate water quality data, and one regression model needs to be selected automatically or manually. The nine regression models in LOADEST and auto-selection by LOADEST were evaluated in the study. Suspended solids data were collected from forty-nine stations from the Water Information System of the Ministry of Environment. Suspended solid data from each station was divided into two groups for calibration and validation. Nash-Stucliffe efficiency (NSE) and coefficient of determination ($R_2$) were used to evaluate estimated suspended solid loads. The regression models numbered 1 and 3 in LOADEST provided higher NSE and $R_2$, compared to the other regression models. The regression modes numbered 2, 5, 6, 8, and 9 in LOADEST provided low NSE. In addition, the regression model selected by LOADEST did not necessarily provide better suspended solid estimations than the other regression models did.
박윤식,김종건,허성구,김남원,안재훈,박준호,김기성,임경재,Park, Youn-Shik,Kim, Jong-Gun,Heo, Sung-Gu,Kim, Nam-Won,Ahn, Jae-Hun,Park, Joon-Ho,Kim, Ki-Sung,Lim, Kyung-Jae 한국농공학회 2008 한국농공학회논문집 Vol.50 No.1
Soil erosion is a natural process and has been occurring in most areas in the watershed. However, accelerated soil erosion rates have been causing numerous environmental impacts in recent years. To reduce soil erosion and sediment inflow into the water bodies, site-specific soil erosion best management practices(BMPs) need to be established and implemented. The most commonly used soil erosion model is the Universal Soil Loss Equation(USLE), which have been used in many countries over 30 years. The Sediment Assessment Tool for Effective Erosion Control(SATEEC) ArcView GIS system has been developed and enhanced to estimate the soil erosion and sediment yield trom the watershed using the USLE input data. In the last decade, the Soil and Water Assessment Tool(SWAT) model also has been widely used to estimate soil erosion and sediment yield at a watershed scale. The SATEEC system estimates the LS factor using the equation suggested by Moore and Burch, while the SWAT model estimates the LS factor based on the relationship between sub watershed average slope and slope length. Thus the SATEEC and SWAT estimated soil erosion values were compared in this study. The differences in LS factor estimation methods in the SATEEC and SWAT caused significant difference in estimated soil erosion. In this study, the difference was -51.9%(default threshold)${\sim}-54.5%$(min. threshold) between SATEEC and non-patched SWAT, and -7.8%(default threshold)${\sim}+3.8%$(min. threshold) between SATEEC and patched SWAT estimated soil erosion.
STEPL WEB 모형을 이용한 농촌지역 비점오염원저감 대책 모의
박윤식,금동혁,정영훈,조재필,임경재,김기성,Park, Youn Shik,Kum, Dong Hyuk,Jung, Young Hun,Cho, Ja Pil,Lim, Kyoung Jae,Kim, Ki Sung 한국농공학회 2014 한국농공학회논문집 Vol.56 No.5
Sediment-laden water is problematic in aquatic ecosystem and for hydraulic structures in a watershed, and agriculture area in a watershed is one of source areas of nonpoint source (NPS), since soil surface typically exposures due to agricultural activities. Especially, severe sediment might flow into stream when agricultural area is located near stream like the Imha-dam watershed. Soil erosion is affected by precipitation, therefore there is a need to consider precipitation characteristics in soil erosion and best management practices (BMPs) simulation. The Web-based Spreadsheet Tool for the Estimation of Pollutant Load (STEPL WEB) allows estimating long-term sediment loads and the impact of best management practices to reduce sediment loads. STEPL WEB and predicted precipitation data by MIROC-ESM model was used to estimate sediment loads and its reduction by filter strip and conversion of agricultural area to forest in the future 30 years. The result indicates that approximately 70 % of agricultural area requires filter strip installation or that approximately 50 % of agricultural area needs to be converted to forest, for 41 % of sediment load reduction.
유역 모델 특성 및 국내 적용 현황과 발전 방향에 대한 검토
박윤식 ( Youn Shik Park ),류지철 ( Jichul Ryu ),김종건 ( Jonggun Kim ),금동혁 ( Donghyuk Kum ),임경재 ( Kyoung Jae Lim ) 한국물환경학회(구 한국수질보전학회) 2020 한국물환경학회지 Vol.36 No.6
In South Korea, the concept of water environment was expanded to include aquatic ecosystems with the Integrated Water Management implementation. Watershed-scale modeling is typically performed for hydrologic component analysis, however, there is a need to expand to include ecosystem variability such that the modeling corresponds to the social and political issues around the water environment. For this to be viable, the modeling must account for several distinct features in South Korean watersheds. The modeling must provide reasonable estimations for peak flow rate and apply to paddy areas as they represent 11% of land use area and greatly influence groundwater levels during irrigation. These facts indicate that the modeling time intervals should be sub-daily and the hydrologic model must have sufficient power to process surface flow, subsurface flow, and baseflow. Thus, the features required for watershed-scale modeling are suggested in this study by way of review of frequently used hydrologic models including: Agricultural Policy/Environmental eXtender(APEX), Catchment hydrologic cycle analysis tool(CAT), Hydrological Simulation Program-FORTRAN(HSPF), Spatio-Temporal River-basin Ecohydrology Analysis Model(STREAM), and Soil and Water Assessment Tool(SWAT).
비점오염원 관리를 위한 국내 농경지 토양유실 예측 정확성 향상 방안
박윤식 ( Youn Shik Park ),김종건 ( Jonggun Kim ),임경재 ( Kyoung Jae Lim ) 한국농공학회 2020 한국농공학회 학술대회초록집 Vol.2020 No.-
Soil erosion is one of major issues worldwide. Soils are valuable natural resources, however once it is transported into stream or river, it leads to water quality degradation. Therefore soil erosion needs to be controlled to prevent water body protection and to preserve as important resources. The Ministry of Environment in South-Korea enacted ‘A bulletin on the Survey of the Erosion of Topsoil’ in 2012 and implement the enforcement ordinance since 2013. The bulletin is based on Universal Soil Loss Equation (USLE) in the procedures, but the approach is inappropriate for entire procedures due to inborn limitation of the equation. Therefore there is a need to revise the bulletin so that measured and estimated soil erosion can be compared. Korean Soil Loss Equation (KORSLE) was selected to estimate soil loss and was applied in the Four major watersheds to evaluate an approach to revise the bulletin. Since the KORSLE provides an opportunity to consider seasonal variance in the country, a revision for the bulletin is required to provide better accuracy on soil erosion estimation with recent rainfall condition and plant growth in agricultural areas.
박윤식 ( Youn Shik Park ),임경재 ( Kyoung Jae Lim ),( Larry Theller ),( Bernard A. Engel ) 한국농공학회 2014 한국농공학회 학술대회초록집 Vol.2014 No.-
The Long-Term Hydrologic Impact Assessment (L-THIA) model is a quick and straightforward analysis tool to estimate direct runoff and nonpoint source (NPS) pollution. The model requires modest effort to collect input data and uses the Soil Conservation Service - Curve Number (SCS-CN) approach to estimate direct runoff. L-THIA was originally implemented as a spreadsheet application. GIS-based versions of L-THIA have been developed in ArcView 3 and upgraded to ArcGIS 9. However, a major upgrade was required for L-THIA to operate in the current version of ArcGIS and to provide more options in runoff and NPS estimation. An updated L-THIA interfaced with ArcGIS 10.0 and 10.1 has been developed in the study as an ArcGIS Desktop Add-in Model. The model provides a user-friendly interface, easy access to the model parameters, and an automated watershed delineation process. Also, the model allows use of precipitation data from multiple gauge locations for the watershed when a watershed is large enough to have more than one precipitation gauge station. The model was applied to a 4,410 square kilometer watershed in which seven precipitation gauge stations are located. The model estimated annual direct runoff well compared to separated direct runoff in the calibration and validation periods of ten and nine years. The NSE and R<sup>2</sup> for the calibration period were 0.59 and 0.62, and they were 0.72 and 0.84 for the validation period. The L-THIA GIS 2013, with a user-friendly interface and enhanced functions, is expected to be a decision support model requiring less effort for GIS processes or to be a useful educational hydrology model.