• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.2
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• pp.75-83
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• 2015

This study was aimed to estimate the total application cost and utilization of Turf grass VFS application through the field experiment. The experimental plots were constructed in an upland field of Iksan city within the Saemangeum watershed. Turf grass was transplanted at the down-slope edge of the pollution source area in each of the treated plots. Three rainfall events were monitored during the experiment period, and the rainfall-runoff relationships and NPS pollution reduction effects of the VFS systems were assessed. As results, the reduction ratio of runoff volume ranged 14.1~64.0 %, while the NPS pollution reduction ratio ranged 9.8~73.9 % for SS, 24.0~84.2 % for T-N, 31.6~80.9 % for T-P respectively. The total cost of VFS application was estimated by considering purchase cost of Turf grass sods and construction and maintenance costs of VFS system as well as the loss caused by giving up crop cultivation for the area needed to construct the VFS. The total cost of the VFS was estimated to be approximately \3,379,000/ha/year for the first year of application, and this cost could be decreased to \1,899,000/ha/year from the second year as the construction cost of VFS could no longer need to be counted afterwards. Apart from the NPS pollution reduction effects, the possible utilization of VFS was examined by detaching Turf grass within 40 % of VFS area for sale during spring time when the VFS systems fully covered. The benefit of selling the detached Turf grass sods was estimated as \1,260,000/ha/year, and also found that the VFS area successfully recovered by the time of the summer period. This benefit could attract farmers to adopt the VFS technique to manage agricultural NPS pollution.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.752-757
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• 2009

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.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.4
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• pp.121-131
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• 2013

This study focused on the sediment reduction effects of VFS (vegetative filter strip) systems for the general characteristics of uplands in Korea. General conditions of upland fields were investigated through national scales of annual agricultural statistics. 7-15 % of slope with loam soil was the dominant types of uplands, and the hydrologic soil group feature usually belong to Type B. The common sizes of uplands were bigger than 0.1 ha and less than 0.2 ha, and 86.2 % of them account for less than 1.0 ha. With this information, 0.1 ha, 0.5 ha, and 1.0 ha of uplands with various shapes and 7-15 % of slopes were considered for the VFS system simulations. 20 mm, 40 mm, and 100 mm of daily precipitation were applied. As a result, the trapping efficiencies of VFS systems were obtained 37.4~100 % for 7 % slope and 18.1~98.0 % for 15 % slope of the less than 1.0ha of uplands. As rainfall increased, sediment loads also increased with slope and slope length increase. Also as size and slope of uplands and slope length increased with VFS length decrease, the trapping efficiency decreased for the same amount of rainfall. The optimum lengths of VFS systems for the givien upland conditions were suggested based on the modelling results with condition of VFS length less than 20 % of upland areas.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.4
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• pp.1-10
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• 2022

A vegetative filter strip (VFS) is one of the best management practices (BMPs) to reduce pollutant loads. This study aims to assess the effectiveness of VFS in dense upland field areas. The study areas are agricultural fields in the Maedae (MD), Gaa (GA), and Jaun (JU) watersheds, where severe sediment yields have occurred and the Korean government has designated them as non-point management regions. The agricultural fields were divided into three or four clusters for each watershed based on their slope, slope length, and area (e.g., MD1, MD2). To assess the sediment trapping (STE) and pesticide reduction efficiency (PRE) of VFS, the Vegetative Filter Strip Modeling System (VFSMOD) was applied with three different scenarios (SC) (SC1: VFS with rye vegetation; SC2: VFS with rye vegetation and a gentle slope in VFS range; and SC3: VFS with grass mixture). For SC1, there were relatively short slope lengths and small areas in the MD1 and GA3 clusters, and they showed higher pollutant reduction (STE>50%, PRE>25%). For SC2 and SC3, all clusters in GA and some clusters (MD1 and MD3) in MD show higher pollutant reduction (>25%), while the uplands in JU still show a lower pollutant (<25%). With correlation analysis between geographic characteristics and VFS effectiveness slope and slope length showed relative higher correlations with the pollutant efficiency than a area. The results of this study implied that slope and slope length should be considered to find suitable upland conditions for VFS installations.

• Journal of Korean Society on Water Environment
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• v.31 no.4
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• pp.407-417
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• 2015

Soil loss is one of the significant disasters which have threatened human community and ecosystem. Particularly, Korea has high vulnerability of soil loss because rainfall is concentrated during summer and mountainous regions take more than 70% of total land resources. Accordingly, the sediment control management plan are required to prevent the loss of soil resources and to improve water quality in the receiving waterbodies. In this regard, the objectives of this study are 1) to quantify the effect of the Vegetative Filter Strip (VFS) on sediment runoff reduction and 2) to analyze the relationship of rainfall intensity and sediment runoff. For this, SATEEC and VFSMOD were used to estimate sediment runoff according to rainfall intensity and to quantify the effect of VFS on sediment runoff reduction, respectively. In this study, the VFS has higher impact on sediment reduction for lower maximum rainfall intensity, which means that the maximum rainfall intensity is one of significant factors to control sediment runoff. Also, the sediment with VFS considered was highly correlated with maximum rainfall intensity. For these results, this study will contribute to extend the applicability of VFS in establishing eco-friendly sediment control plans.

• Journal of Korean Society on Water Environment
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• v.33 no.3
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• pp.247-255
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• 2017

This research was conducted to analyze removal efficiencies of non-point pollution source (NPS) in low impact development (LID) facilities with vegetation. In this research, removal efficiencies of NPS were calculated using rainfall monitoring data for 5 years in grassed swale (GS) and vegetative filter strip (VFS). TSS was greater than other pollutants, and it ranged 11.9 ~ 351.7 mg/L in GS and 12.8 ~ 350.7 mg/L in VFS. Outflow EMCs were reduced than inflow EMCs, overall removal efficiencies of NPS were 67 ~ 86% in GS and 63 ~ 91% in VFS. 50 % reduction efficiency of rainfall runoff was observed between inflow and outflow in each LID facility. TSS removal efficiency in GS and VFS was correlated with rainfall characteristics. The rainfall for TSS removal efficiency over 50% was determined about 31 mm, 34 mm and average rainfall intensity was 3.0 mm/hr, 3.9 mm/hr in GS and VFS. Therefore, GS and VFS were regarded effective LID facilities as removal of pollutants and rainfall runoff. Also, this research result can be used as an important data for management of NPS.

• Journal of Korean Society on Water Environment
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• v.30 no.2
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• pp.159-165
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• 2014

Vegetative Filter Strip (VFS) is one of effective Best Management Practices (BMPs) to prevent sediment-laden water problem, is installed at the edge of source area such agricultural area so that sediment occurred in source area is trapped by VFS before it flow into stream or river. Appropriate scale of it needs to be simulated before it is installed, considering various field conditions. In this study, a model using VFSMOD-w model and Genetic Algorithm to determine effective VFS length was developed, it is available to calibrate input parameter related to source area sediment yield through thousands of VFSMOD-w simulations. Useful DBs, moreover, are stored in the model so that very specific input parameters can be used with reasonable values. Compared simulated values to observed data values for calibration, R2 and Nash-Stucliffe model efficiency coefficient were 0.74 and 0.65 in flow comparison, and 0.89 and 0.79 in sediment comparison. The model determined 1.0 m of Filter Length, 0.18 of Filter Slope, and 0.2 cm of Filter Media Spacing to reduce 80% of sediment by VFS. The model has not only Auto-Calibration module also DBs for specific input parameters, thus, the model is expected to be used for effective VFS scale.

• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.6
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• pp.9-19
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• 2019

Vegetative Filter Strip (VFS) is the best management practice which has been widely used to mitigate water pollutants from agricultural fields by alleviating runoff and sediment. This study was conducted to improve an equation for estimating sediment trapping efficiency of VFS using several different regularization methods (i.e., ordinary least squares analysis, LASSO, ridge regression analysis and elastic net). The four different regularization methods were employed to develop the sediment trapping efficiency equation of VFS. Each regularization method indicated high accuracy in estimating the sediment trapping efficiency of VFS. Among the four regularization methods, the ridge method showed the most accurate results according to $R^2$, RMSE and MAPE which were 0.94, 7.31% and 14.63%, respectively. The equation developed in this study can be applied in watershed-scale hydrological models in order to estimate the sediment trapping efficiency of VFS in agricultural fields for an effective watershed management in Korea.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.5
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• pp.155-163
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• 2004

The objectives of this study were to characterize the wastewater flow through the VFS, and relate this to the P removal in the VFS. A total of 68 subsurface wells (20∼40 cm below the soil surface) and 35 surface wells (0~5 cm), and the application of chloride tracer were used to investigate flow paths and soluble reactive P (SRP) removal from the 21 m wide and 33 m long VFS receiving dairy milkhouse waste. The early chloride breakthroughs in wells in the center of the VFS showed that the milkhouse waste flows preferentially down in the center of the hillslope. The locally saturated area created near the discharge pipe in the center of the VFS accelerates surface flow that contributed to rapid transport of P to the down slope area. Although VFS of 33m long eventually reduced SRP to lower than 0.2 mg/L in most cases, SRP is less effectively removed in the areas where soil saturation occurred. It is suggested that the effort to distribute the wastewater uniformly to avoid soil saturation and reduce the flow velocity need to be considered in new designs.

• Journal of Korean Society on Water Environment
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• v.31 no.5
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• pp.482-490
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• 2015

In this study, considering the factors that affects sediment trapping efficiency of Vegetative Filter Strips (VFS), the scenarios were designed to develop a regression equation to estimate sediment trapping efficiency of VFS for agricultural fields in South-Korea. For this, general conditions of agricultural fields in South-Korea were investigated. Then, based on these results, total 53,460 scenarios were set and simulated by Vegetative Filter Strip MODel (VFSMOD-w). Two variables were determined from the results of 53,460 scenarios. These two variables were applied to CurveExpert for development of a equation, which can estimate sediment trapping efficiency of VFS. The equation developed in this study can be used in SWAT model for estimation of sediment reduction efficiency of VFS to upland field in Korea. Moreover, it is expected that VFS will be effectively applied to agricultural fields in South-Korea.