• Journal of Korean Society on Water Environment
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• v.29 no.1
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• pp.29-35
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• 2013

Recently, various Best Management Practices (BMPs) have been applied at a field to reduce soil erosion. Hourly Runoff and Sediment Model for Best Management Practices (HRSM4BMP) model could be used to evaluate soil erosion reduction for various agricultural BMPs at fields. Runoff and sediment yield from source areas have to be predicted with greater accuracies to evaluate sediment reduction efficiently with BMPs. To achieve this, the best parameters related with runoff and sediment modules of the HRSM4BMP model should be identified with proper calibration processes. Although manual calibration is often utilized in calibrating runoff and sediment using the HRSM4BMP, objective calibration method would be recommended. The purpose of the study was to develop an automatic calibration tool of the HRSM4BMP model with PARASOL method. This automatic calibration tool was applied to Bangdongri, Chuncheon-si to evaluate its calibration performance. The $R^2$, NSE and RMSE value for runoff estimation were 0.92, 0.92, $0.3m^3$, and for sediment yield estimation were 0.94, 0.94, 0.0027 kg. As shown in this result, automatic calibration tool of HRSM4BMP model would be used to determine the best parameters and can be used to simulate runoff and sediment yield with acceptable accuracies.

• Journal of Soil and Groundwater Environment
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• v.25 no.3
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• pp.52-64
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• 2020

The universal soil loss equation (USLE), a model for estimating the potential soil loss, has been used not only in research areas but also in establishing national policies in South Korea. Despite its wide applicability, USLE cannot adequately address the effect of seasonal variances. To overcome this limit, the ArcGIS-based Sediment Assessment Tool for Effective Erosion (ArcSATEEC) has been developed as an alternative model. Although the field-scale (< 100 ㎡) application of this model produced reliable estimation results, it is still challenging to validate accuracy of the model estimation because it only estimates potential soil losses, not the actual sediment yield. Therefore, in this study, a method for estimating actual soil loss based on the ArcSATEEC model was suggested. The model was applied to eight watersheds in South Korea to estimate sediment yields. Correction factor was introduced for each watershed, and the estimated sediment yield was compared with that of the estimated yield by LOAD ESTimator (LOADEST). Sediment yield estimation for all watersheds exhibited reliable results, and the validity of the proposed correction factor was confirmed, suggesting the correction factor needs to be considered in estimating actual soil loss.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.2
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• pp.19-26
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• 2011

SATEEC ArcView GIS system was developed using the Universal Soil Loss Equation (USLE) and sediment delivery ratio (SDR) modules. In addition, time-variant R and C modules and $R_5$ module were developed and integrated into the SATEEC system in recent years. The SATEEC ArcView GIS 2.1 system is a simple-to-use system which can estimate soil erosion and sediment yield spatially and temporarily using only USLE input data, DEM, and daily rainfall dataset. In this study, the SATEEC 2.1 system was used to evaluate the effects of USLE LS input data considering slope length segmentation on soil erosion and sediment yield estimation. Use of USLE LS with slope length segmentation due to roads in the watershed, soil erosion estimation decreased by 24.70 %. However, the estimated sediment yield using SATEEC GA-SDR matched measured sediment values in both scenarios (EI values of 0.650 and EI 0.651 w/o and w/flow segmentation). This is because the SATEEC GA-SDR module estimates lower SDR in case of greater soil erosion estimation (without flow length segmentation) and greater SDR in case of lower soil erosion estimation (with flow length segmentation). This indicates that the SATEEC soil erosion need to be estimated with care for accurate estimation of SDR at a watershed scale and for accurate evaluation of BMPs in the watershed.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.983-990
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• 2011

Universal Soil Loss Equation (USLE) has been used to estimate potential long-term soil erosion in the fields. However, the USLE does not estimate sediment yield due to lack of module considering sediment delivery ratio (SDR) for watershed application. For that reason, the Sediment Assessment Tool for Effective Erosion Control (SATEEC) system was developed and applied to compute the sediment yield at watershed scale. However, the R factor of current SATEEC Ver. 2.1 was estimated based on 5-day antecedent rainfall, it is not related with fundamental concept of R factor. To compute R factor accurately, the energy of rainfall strikes should be considered. In this study, the R module in the SATEEC system was enhanced using formulas of Williams, Foster, Cooley, CREAMS which could consider the energy of rainfall strikes. The enhanced SATEEC system ver. 2.2 was applied to the Imha watershed and monthly sediment yield was estimated. As a result of this study, the $R^2$ and NSE values are 0.591 and 0.573 for calibration period, and 0.927 and 0.911 for validation period, respectively. The results demonstrate the enhanced SATEEC System estimates the sediment yield suitably, and it could be used to establish the detailed environmental policy standard using USLE input dataset at watershed scale.

• Journal of Korean Society on Water Environment
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• v.23 no.4
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• pp.518-526
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• 2007

There have been serious soil erosion and water pollution problems caused by highland agriculture practices at Doam-dam watershed. Especially agricultural activities, chemical and organic fertilizer and pesticide applications, soil reconditioning to maintain soil fertility are known as primary causes of soil erosion and water qaulity degradation in the receiving water bodies. Among these, soil reconditioning can accelerate soil erosion rates. To develop soil erosion prevention practices, it is necessary to estimate the soil erosion from the watershed. Thus, the Universal Soil Loss Equation (USLE) model has been developed and utilized to assess soil erosion. However, the USLE model cannot be used at watershed scale because it does not consider sediment delivery ratio (SDR) for watershed application. For this reason, the Sediment Assessment Tool for Effective Erosion Control (SA TEEC) was developed to assess the sediment yield at any point in the watershed. The USLE-based SA TEEC system can estimate the SDR using area-based SDR and slope-based SDR module. In this study, the SATEEC system was used to estimate soil erosion and sediment yield at the Doam-dam watershed using the soil properties from reconditioned agricultural fields. Based on the soil sampling and analysis, the US LE K factor was calculated and used in the SA TEEC system to analyze the possible errors of previous USLE application studies using soil properties from the digital soil map, and compared with that using soil properties obtained in this study. The estimated soil erosion at the Doam-dam watershed without using soil properties obtained in the soil sampling and analysis is 1,791,400 ton/year (123 ton/ha/year), while the soil erosion amount is 2,429,900 ton/year (166.8 ton/ha/year) with the use of soil properties from the soil sampling and analysis. There is 35 % increase in estimated soil erosion and sediment yield with the use of soil properties from soil reconditioned agricultural fields. Since significant amount of soil erosion are known to be occurring from the agricultural fields, the soil erosion and sediment yield from only agricultural fields was assessed. The soil erosion rate is 45.9 ton/ha/year without considering soil properties from soil reconditioned agricultural fields, while 105.3 ton/ha/year after considering soil properties obtained in this study, increased in 129%. This study shows that it is very important to use correct soil properties to assess soil erosion and sediment yield simulation. It is recommended that further studies are needed to develop environment friendly soil reconditioning method should be developed and implemented to decrease the speed of soil erosion rates and water quality degradation.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.2
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• pp.1-11
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• 2018

Probable Maximum Flood (PMF) is mostly applied for the designs of large-scale hydraulic structures and it is estimated by computing the runoff hydrograph where Probable Maximum Precipitation (PMP) is inserted as design rainfall. The existing PMP is estimated by transferring the heavy rainfall from all watersheds of korea to the design watershed, however, in this study, PMP was analyzed by selecting only rainfall events occurred in the design watershed. And then, Catchment-scale Soil Erosion Model (CSEM) was used to estimate the PMF and sediment-runoff yield according to the watershed-based estimated PMP. Although the PMF estimated in this study was lower than the existing estimated PMF in the Yongdam-dam basin, it was estimated to be higher than the 200-year frequency design flood discharge. In addition, sediment-runoff yield was estimated with a 0.05 cm of the maximum erosion and a 0.06 cm of the maximum deposition, and a total sediment-runoff yield of 168,391 tons according to 24-hour PMP duration.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.1
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• pp.131-140
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• 1993

The major objective of this study is to develop practical methods for estimating sediment yield rates of medium size watersheds of which areas range from 200 to $2,000km^2$ In the first phase of the study that were presented in the companion paper followed by this paper, a methodology for estimating sediment yield rate was introduced and a total of 13 data points including eight sampled river-sediment data and five reservoir deposit data were collected. In this study, a three-parameter empirical model and a six-parameter rating model, both of which are based on empiricism, have been developed. By limited comparisons, the models developed in this study appear to be more reliable and applicable than the existing ones. According to the sediment yield data collected and the estimations by the models, meanwhile, the lowest value for the sediment yield rate of medium size watersheds in Korea is estimated to be about $100tons/km^2/yr$, and the maximum to be about $1,000tons/km^2/yr$.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.1
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• pp.121-130
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• 1993

The major objective of this study is to develop practical methods for estimating sediment yield rates of medium size watersheds of which areas range from 200 to $2,000km^2$. For this purpose, this study adopts an empirical method of statistical approach and another empirical method of weighting the watershed characteristics factors. A total of 13 data points for sediment yield rate, including five data points from reservoir deposit data and eight data points from sampled river-sediment data have been collected. Meanwhile, seven factors that may affect the sediment yield rate of a watershed have been selected. They are drainage density, rainfall erosivity, ground cover and land use, soil erodibility, topography, river-bed material characteristics, and watershed area. In the companion paper following this paper, methods for estimating sediment yield rate are to be developed using the 13 data points collected and seven watershed characteristics factors selected in this study.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.3
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• pp.97-104
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• 2010

The purpose of this study is to evaluate sediment yield reduction under various field slope conditions with rice straw mat. The Vegetative Filter Strip Model-W (VFSMOD-W) and Soil and Water Assessment Tool (SWAT) were used for simulation of sediment yield reduction effect of rice straw mat. The Universe Soil Loss Equation Practice factor (USLE P factor), being able to reflect simulation of rice straw mat in the agricultural field, were estimated for each slope with VFSMOD-W and measured soil erosion values under 5, 10, and 20 % slopes. Then with the regression equation for slopes, USLE P factor was derived and used as input data for each Hydrological Response Unit (HRU) in the SWAT model. The SWAT Spatially Distributed-HRU (SD-HRU) pre-processor module was utilized, moreover, in order to consider spatial location and topographic features (measured topographic features by field survey) of all HRU within each subwatershed in the study watershed. Result of monthly sediment yield without rice straw mat (Jan. 2000 - Aug. 2007) was 814.72 ton/month, and with rice straw mat (Jan. 2000 - Aug. 2007) was 526.75 ton/month, which was reduced as 35.35 % compared without it. Also, during the rainy season (from Jun. to Sep. 2000 - 2007), when without vs. with rice straw mat, monthly sediment indicated 2,109.54 ton and 1,358.61 ton respectively. It showed about 35.60 % was reduced depending on rice straw mat. As shown in this study, if rice straw mat is used as a Best Management Practice (BMP) in the sloping fields, rainfall-driven sediment yield will be reduced effectively.

• Journal of Environmental Impact Assessment
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• v.17 no.4
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• pp.243-253
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• 2008

The purpose of this study was to simulate the reduction effect of soil loss in the Yongdam reservoir watershed using SWAT model. To evaluate accuracy for flow and sediment yield of SWAT model, calibration was performed for the period from Jan. 2002 to Dec. 2003, and the verification for Jan. 2005 to Dec. 2005. The calibration and the verification were carried out using data observed at the Cheoncheon gaging station. The $R^2$ and EI values in terms of a flow were 0.8 and 0.78 respectively for calibration, whereas they for verification were 0.88 and 0.86 respectively. In terms of a sediment yield, they were 0.7 and 0.48 respectively for calibration, whereas for verification were 0.64 and 0.54 respectively. As a results from model simulation, annual mean soil loss rates in terms of forest, paddy and upland were 0.02 ton/ha/yr, 0.15 ton/ha/yr and 7.58 ton/ha/yr, respectively. The results show that the land use type of a upland has more significant impact on a total soil loss as well as a sediment yield than other types of land use. The sediment delivery ratio was determined to be about 0.35. In this study 2 land cover change scenarios for upland area were considered. These scenarios were used an input to SWAT model in order to evaluate their impact on soil loss and sediment delivery. The results show that a reduction of the upland area would reduce the soil loss and sediment yield.