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SWAT HRU의 공간적인 지형 특성을 고려한 유사평가 분석
장원석 ( Jang Wonseok ),유동선 ( Yoo Dongseon ),박윤식 ( Park Younshik ),김종건 ( Kim Jonggun ),최중대 ( Choi Joongdae ),임경재 ( Lim Kyoung Jae ) 한국농공학회 2008 한국농공학회 학술대회초록집 Vol.2008 No.-
There are wide ranges of hydrologic and water quality models available. Among those the watershed scale Soil and Water Assessment Tool (SWAT) has been widely used, compared with other models because of its prediction accuracy and functionalities in simulating the runoff, sediment, nutrient, and pesticide at spatial and temporal context. The SWAT model, semi-distributed model, first divides the watershed into multiple subwatersheds, and then extracts the basic computation element, called the Hydrologic Response Unit (HRU) with land use and soil maps. In the process of HRU generation, the spatial information of land use and soil maps within each subwatershed is lost because the SWAT model is semi-distributed model. In other words, the areas with the same land use and the same soil are grouped into one single HRU within each subwatershed although its topographic features are significantly different. The SWAT model estimates the HRU topographic data based on the average slope of each subwatershed, and then use these topographic data for all HRUs within the subwatershed. To improve the SWAT capabilities for various watershed scenarios, the Spatially-Distributed HRU (SD-HRU) module was developed in this study to simulate site-specific topographic data, instead of using the same topographic data for all HRUs. The SD-HRU was applied to the Hae-an watershed, where field slope lengths and slopes are measured for all agricultural fields to examine the necessity of using the SD-HRU in accurate sediment simulation using the SWAT model. It was found that the simulated sediment decreased by 26 %, compared with currently available SWAT model and decreased by 68 %, compared with the result using SWAT area-weighted slope and slope length module. The analysis revealed that the SD-HRU module needs to be applied in SWAT sediment simulation for accurate analysis of soil erosion and sediment behaviors. If the SD-HRU module is not applied in SWAT runs, the other SWAT factors may be over or under estimated, resulting in errors in physical and empirical computation modules although the SWAT estimated flow and sediment values match the measured data reasonably well.
Water Quality Assessment at Jinhae Bay and Gwangyang Bay, South Korea
Kim, Dongseon,Baek, Seung Ho,Yoon, Dong-Young,Kim, Kyung-Hee,Jeong, Jin-Hyun,Jang, Pung-Guk,Kim, Young-Ok 한국해양학회 2014 Ocean science journal Vol.49 No.3
A new water quality index for evaluating the water quality of Jinhae Bay and Gwangyang Bay was developed. Four water quality parameters were selected as water quality indicators for the water quality index: dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), chlorophyll-a (Chl-a), and dissolved oxygen (DO). Reference levels of DIN, DIP, and Chl-a were determined as $6.22{\mu}mol\;L^{-1}$, $0.38{\mu}mol\;L^{-1}$, and $2.32{\mu}mol\;L^{-1}$, respectively, on the basis of a long-term dataset that was collected monthly in the Korea Strait over a period of seven years (2006-2012). The water quality index established for Jinhae Bay and Gwangyang Bay is (bottom DO grade ${\times}0.33$) + (surface Chl-a grade ${\times}0.33$) + (surface DIN grade ${\times}0.17$) + (surface DIP grade ${\times}0.17$). On the basis of a three-year observation, the water quality of Jinhae Bay was classified as "good" in winter and spring, "poor" in summer, and "fair" in autumn and exhibited large spatial variation, with the lowest-quality water observed in Masan Bay. The water quality of Gwangyang Bay was classified as "good" in winter, "fair" in spring, "poor" in summer, and "fair" in autumn. Unlike Jinhae Bay, the water quality of Gwangyang Bay exhibited minimal spatial variation. In both bays, water quality among the four seasons was worse during summer. It is essential that a survey for water quality evaluation be conducted during summer.
실측 경사장 및 경사도를 고려한 양구 해안면 유역의 유사량 평가
유동선 ( Dongseon Yoo ),박윤식 ( Younshik Park ),김종건 ( Jonggun Kim ),장원석 ( Wonseok Jang ),김기성 ( Ki-sung Kim ),임경재 ( Kyoung Jae Lim ) 한국농공학회 2008 한국농공학회 학술대회초록집 Vol.2008 No.-
In this study, area-weighted slope and slope length module, considering measured field slope and slope length of the agricultural fields within the subwatershed, was developed using the ArcView Avenue programming to reflect the field topography of the SWAT(Soil and Water Assessment Tool) HRU in simulating the hydrology and water quality. Flow and sediment yield estimated values of the SWAT were compared with and without applying area-weighted slope and slope length module, developed in this study. There was 103% increases in estimated sediment with area-weighted slope and slope length module for the study watershed. The soil erosion and sediment yield from only agricultural field in Hae-an watershed was also assessed. There are 111% increase in estimated soil erosion and 112% increase in estimated sediment by applying area-weighted slope and slope length module.
VFSMOD-W 모형을 이용한 SWAT 모형의 초생대 유사 저감 효율 모듈 개선
박윤식 ( Younshik Park ),김종건 ( Jonggun Kim ),장원석 ( Won-seok Jang ),유동선 ( Dongseon Yoo ),최중대 ( Joongdae Choi ),임경재 ( Kyoung Jae Lim ) 한국농공학회 2008 한국농공학회 학술대회초록집 Vol.2008 No.-
Environment problem has been arising in many countries. Especially, soil erosion has been deemed as one of the biggest issues because sediment causes muddy water and pollutants, such as agricultural chemicals, flow in the stream with this sediment. Many studies, regarding soil loss and non-point source pollution from watershed, has been performed while serious problem has been known. Soil loss occurred in most agricultural area by rainfall and runoff. It makes hydraulic structure unstable, causes environmental economical problems because muddy water destroys ecosystem and causes intake water deterioration. As revealing serious effects of muddy water by sediment, many researches have been doing with various methods. Hydraulic structures establishments such as soil erosion control dams and grit chamber are common. Vegetative filter strip is investigated in this study because vegetative filter strip is designed for reducing sediment from upland areas of the watershed, and it has many functions, not only sediment reduction but also runoff water quality improvement and wildlife habitat. With these positive functions of the vegetative filter strip, the study about vegetative filter strip has been increasing for reducing sediment because it is more effective than hydraulic structures from an environmental perspective. But the sediment trapping efficiency by vegetative filter strip, needs to be investigated and designed first. Therefore the model, VFSMOD-W, was used in this study as it can estimate sediment trapping efficiency of vegetative filter strip under various field, vegetation, weather condition. Sensitive factors to sediment trapping efficiency are studied with VFSMOD-W, and sediment trapping efficiency equation has been derived using two most sensitive factors. It is thought that the equation suggested in this study can be used in Soil and Water Assessment Tool (SWAT), to overcome the limit of SWAT filter strip module, which is based solely on filter strip width.