부유사 부하량 예측을 위한 LOADEST WEB의 적용

박윤식,( Bernie Engel ),( Jane Frankenberger ),황하선 한국물환경학회(구 한국수질보전학회) 2015 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2015 No.-

Web GIS 기반의 오염 부하지속곡선 시스템을 이용한 유역의 수질 및 특성 분석

김종건 ( Jonggun Kim ),( Bernie Engel ),박윤식 ( Youn Shik Park ),( Larry Theller ),( Indrajeet Chaubey ),임경재 ( Kyoung Jae Lim ) 한국농공학회 2009 한국농공학회 학술대회초록집 Vol.2009 No.-

수질오염총량관리제도(TMDL)는 유역의 수질 회복 및 관리를 위해 우리나라를 비롯해 미국의 여러 주에서 수립되어 적용되고 있다. 현재 미국에서는 유역 관리를 위한 TMDL의 기준설정에 있어 오염부하지속 곡선(LDC)의 활용이 급격히 증가되고 있다. 그러나 기존의 LDC 방법은 사용자로 하여금 충분한 교육이 필요하고 LDC 생성을 위한 데이터 구축이 수동적으로 이루어지고 있다. 이러한 문제를 해결하기 위해 본 연구에서는 Web GIS 기반의 LDC 시스템을 개발하였다 (http://www.EnvSys.co.kr/~ldc). 웹기반의 LDC시스템은 미국 지질 조사국(USGS)이나 한국 환경부(MOE) 서버 등을 통해 구축된 자료를 이용하여 오염부하지속곡선을 생성하기까지의 모든 과정이 자동으로 처리되어 기존 수작업에 의한 방법의 단점을 보완하고 있다. 그리하여 본 연구에서는 우리나라 수질오염 총량 관리제도 단위유역인 낙본A와 금본C, 그리고 미국 인디애나 주의 Yellow River와 펜실베이니아 주의 Borkenstraw Creek 유역을 대상으로 웹기반 LDC시스템을 이용하여 유역의 특성을 분석하였다. 본 연구에서 사용된 유량 및 수질 자료는 본 시스템에서 연계된 환경부 서버와 USGS 서버를 통해 구축하였다. 분석 결과 낙본 A 단위유역의 BOD 오염부하량과 농도가 대체적으로 목표수질 기준을 만족하는 것으로 나타났으나 전반적으로 유량이 적을 때 다소 목표수질을 초과하고 있는 나타나, 적합한 수질관리 대책이 필요한 것으로 분석되었다. 금본 C 단위유역의 경우 대부분 BOD 배출부하량이 할당 부하량보다 낮게 나타나는 것을 알 수 있고, 목표수질 농도에 비해 배출되는 BOD 농도 또한 대체적으로 낮은 것을 알 수 있다. 또한 Yellow River 유역의 경우는 유량이 많을 때배출되는 수질농도가 목표수질을 초과하는 것으로 보아 강우시 배출되는 오염물에 대한 대책이 요구되고, Borkenstraw Creek 유역의 경우 유량이 적을 때를 제외하고 대부분 구간에서 배출부하량이 할당부하량을 초과하여 이에 대한 적합한 수질관리가 필요할 것으로 분석되었다. 본 연구의 결과에서 나타난 바와 같이 웹기반 LDC 시스템을 통해 수질오염총량관리제도 단위유역에 대한 수질 평가 및 특성 분석이 용이하며 수질 회복을 위한 근본적인 해결방법을 제시할 수 있을 것으로 판단된다.

한국지형에서 정확한 토양유실 평가를 위한 SWAT DWDM 개발

장원석 ( Wonseok Jang ),( Bernie Engel ),박윤식 ( Yoon Shik Park ),김종건 ( Jonggun Kim ),최중대 ( Joongdae Choi ),양재의 ( Jae E Yang ),임경재 ( Kyoung Jae Lim ) 한국농공학회 2009 한국농공학회 학술대회초록집 Vol.2009 No.-

Among wide range of hydrologic and water quality models, watershed scale SWAT has been widely used worldwide. The semi-distributed SWAT model extracts basic hydrologic and water quality computation element for each Hydrologic Response Unit (HRU) within subbasin. However, average topographic features of each subwatershed are used for topographic data of all HRUs within the subwatershed. Thus, very detailed subwatershed networks need to be delineated for accurate simulation. In this study, dual watershed delineation module (DWDM) was developed to delineate subwatershed boundary based on agricultural field boundaries and user-provided threshold value. Also, measured topographic data for these small watersheds, i.e., agricultural field watershed, can be used in simulation with spatially-distributed HRU module developed in this study. For non-agricultural subwatersheds, a module capable of calculating topographic data based on the DEM was developed, instead of regression relationship between subwatershed slope and field slope length, default method in current SWAT. These modules were applied to intensively cultivated agriculture-dominant watershed in Korea and it was found that these modules should be used for accurate estimation. Otherwise, other factors may be over/under estimated resulting in errors in physical and empirical computation modules although the SWAT estimated flow and sediment values match measured data reasonably well.

LOADEST를 이용한 연간 부유사 오염부하량 추정을 위한 수질자료 검토

박윤식 ( Youn Shik Pak ),( Bernie Engel ) 한국농공학회 2016 한국농공학회 학술대회초록집 Vol.2016 No.-

Since water quality sampling implementation requires significant labors and is costly to collect and to analyze samples, water quality samples are collected less frequently than flow. LOADEST is used to predict water quality concentration (or load) on days when flow data are measured so that the water quality is to be sufficient for annual pollutant load estimation. However, there is a need to identify the requirement of water quality data. Annual sediment load estimates from 211 locations were analyzed, and it was found that the mean of flow in calibration data were correlated to model behaviors. Also, a regression was developed to compute the required mean of flow in calibration data to calibrate the regression model coefficients. LOADEST runs were performed to investigate the correlation between the mean flow in calibration data and the model behaviors, as daily water quality data were subsampled. It was found that annual load estimates using calibration data of the required mean flow in calibration data by the regression have showed small error to the measured annual load. Moreover, a lot of water quality data by extensive sampling strategies did not always lead to the annual load estimates of small error.

Development of Optimization Module in the WHAT Web GIS System for Accurate Hydrograph Analysis and Model Application

( Kyoung Jae Lim ),( Jong-gun Kim ),( Bernie Engel ),( Ji-hong Jeon ),( Yong-chul Shin ),( Sung-gu Heo ),( Yoon-sik Park ),( Ki-sung Kim ),( Joongdae Choi ) 한국농공학회 2006 한국농공학회 학술대회초록집 Vol.2006 No.-

Over the last years, significant areas in the watershed have been converted into impervious areas with human-induced development activities. These activities resulted in changes in the hydrologic response characteristics and pollutant generation trends. Thus, many hydrologic and water quality computer models have been developed and used to assess hydrologic and water quality impacts of land use changes. However, these models have to be first validated prior to the application in environmenct-friendly land use planning. The direct runoff estimation module of the Long-Term Hydrologic Impact Assessment (L-THIA) ArcView GIS system was validated using the Web GIS-based Hydrograph Analysis Tool, called WHAT (http://pasture.ecn.purdue.edu/~what).The L-THIA model was applied to the Little Eagle Creek (LEC) watershed and compared with the BFLOW filtered direct runoff values. The R2 value was 0.68, Nash-Sutcliffe coefficient value was 0.64.Also, the L-THIA estimates were compared with those separated using the Eckhardt digital filter (w/ default BFImax value of 0.80).The R2 value was 0.66, Nash-Sutcliffe coefficient value was 0.63.Although these results could indicate that the L-THIA model is good in estimating the direct runoff reasonably well, the filtered direct runoff values using the BFLOW and Eckhardt digital filter with the default BFImax value do not reflect hydrological and hydrogeological situations in the LEC watershed. Thus, the hydrograph recession curve analysis was automated using CGI programming and optimization module was developed. These two modules were integrated into the WHAT system for determination of the optimum BFImax parameter of the Eckhardt digital filter. The recession curve analysis method was used to separate baseflow because the shape of hydrograph reflects hydrological and hydrogeological situations in the LEC watershed. With automated recession curve analysis method and optimization module of the WHAT system, the optimum BFImax value of 0.597 was determined. The comparison of the L-THIA estimates with filtered direct runoff using optimized BFImax value of 0.597 resulted in the R2 value of 0.66 and the Nash-Sutcliffe coefficient value of 0.63.However, the L-THIA estimates calibrated with optimized BFImax increased by 17%and the L-THIA estimated NPS pollutant loadings increased by more than 20%.This indicates the L-THIA model direct runoff estimates can be wrong by 17% and NPS pollutant loading estimation by more than 20% if accuracy of baseflow separation method is not validated for the study watershed. This study shows the importance in baseflow separation in hydrologic and water quality modeling using the L-THIA model.

직접유출량 모의를 위한 ArcGIS 기반의 모형 개발 및 개선

김종건 ( Kim Jonggun ),임경재 ( Lim Kyoung Jae ),( Engel Bernie ),차상선 ( Cha Sang Sun ),박찬기 ( Park Chan-gi ),박윤식 ( Park Youn Shik ) 한국농공학회 2018 한국농공학회논문집 Vol.60 No.6

The Long-Term Hydrologic Impact Assessment (L-THIA) model is a quick and straightforward analysis tool to estimate direct runoff and nonpoint source pollution. 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 Tool. The model provides a user-friendly interface, easy access to the model parameters, and an automated watershed delineation process. 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 estimated annual direct runoff well for our study area compared to separated direct runoff in the calibration and validation periods of ten and nine years. The ArcL-THIA, 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.

HRU 단위 라우팅을 위한 SWAT 모형의 개선

박윤식 ( Youn Shik Park ),김종건 ( Jonggun Kim ),김남원 ( Nam Won Kim ),( Bernie Engel ),신동석 ( Dong Seok Shin ),옥용식 ( Yong Sik Ok ),최중대 ( Joongdae Choi ),임경재 ( Kyoung Jae Lim ) 한국농공학회 2009 한국농공학회 학술대회초록집 Vol.2009 No.-

In the last decade, many methods such as greet chamber, reservoir, or debris barrier, have been utilized to manage and prevent muddy water problem. The Vegetative Filter Strip (VFS) has been thought to be one of the most effective methods to trap sediment effectively. The VFS are usually installed at the edge of agricultural areas adjacent to stream or drainage ditches, and it has been shown that the VFS effectively removes pollutants transported with upland runoff. But, if the VFS is installed without any scientific analysis of rainfall-runoff characteristics, soil erosion, and sediment analysis, it may not reduce the sediment as much as expected. Although Soil and Water Assessment Tool (SWAT) model has been used worldwide for many hydrologic and Non-Point Source Pollution (NPSP) analysis at a watershed scale. but it has many limitations in simulating the VFS. Because it considers only 'filter strip width' when the model estimates sediment trapping efficiency, and does not consider the routing of sediment with overland flow option which is expected to maximize the sediment trapping efficiency from upper agricultural subbasin to lower spatially-explicit filter strip. Therefore, the SWAT overland flow option between landuse-subbasins with sediment routing capability was enhanced with modifications in SWAT watershed configuration and SWAT engine. The enhanced SWAT can simulate the sediment trapping efficiency of the VFS in the similar way as the desktop VFSMOD-w system does. Also it now can simulate the effects of overland flow from upper subbasin to reflect the increased runoff volume at the receiving subbasin, which is what is occurring at the field if no diversion channel is installed. In this study, the enhanced SWAT model was applied to small watershed located at Jaun-ri in South Korea to simulate diversion channel and spatially-explicit VFS. It was found that approximately sediment can be reduced by 31%, 65%, 68%, with diversion channel, the VFS, and the VFS with diversion channel, respectively.

Google Map 기반 USGS HYSEP 기저유출 분리 시스템 개발

장원석 ( Won Seok Jang ),박윤식 ( Youn Shik Park ),김종건 ( Jong Gun Kim ),유동선 ( Dong Seon Yoo ),( Bernie Engel ),임경재 ( Kyoung Jae Lim ) 한국물환경학회 2009 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2009 No.-