• Journal of the Korean Society of Environmental Restoration Technology
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• v.3 no.4
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• pp.52-59
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• 2000

This study was carried out to find out effect of by-product gypsum on reducing soil erosion at the sloping burned area at Sampo-ri, Gosung-gun in Kangwon-province during the period between June 28 and Sept. 30, 2000. Four experimental plots ($1.2m{\times}10m$) were prepared at the study area with slopes $15^{\circ}{\sim}18^{\circ}$ where forest fire took place twice during last 4 years. Phosphogypsum (PG) was applied to the soils of the 4 plots at the rates of 0 (control), 5, 7.5, and 10 ton/ha, respectively. Amount of rainfall, runoff, and soil loss were measured 7 times during the study. In the beginning, the amounts of runoff and soil loss from the PG treated plots were not different from those from the control plot due to steepness of the plots. However, the difference between the amount of runoff and soil loss from the PG treated plots and those from the control became apparent over time. The effect of PG treatment lasted until at least 870 mm of rainfall. Compared to the cumulative runoff from the control plot, the cumulative runoff from the plots treated with 5, 7.5, and 10 ton/ha PG decreased 7%, 31 %, and 35%, respectively. The cumulative soil loss from the plots treated with 5, 7.5, and 10 ton/ha PG decreased 44%, 53%, and 77% compared to that from the control plot. Strong acidity of PG (pH 2.0~2.5) did not affect the acidity of the soil and runoff.

• Korean Journal of Hydrosciences
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• v.6
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• pp.81-98
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• 1995

A linear reservoir rainfall-runoff system was developed as a rainfall-runoff event simulation model. It was achieved from large modification of runoff function method. There are six parameters in the model. Hydrologic losses consist of some quantity of initial loss and some ratio of rainfall intensity followed by initial loss. The model has analytical routing equations. Hooke and Jaeves algorithm was used for model calibration. Parameters were estimated for flood events from '84 to '89 at Seomyeon and Munmak stream gauges, and the trends of major parameters were analyzed. Using the trends, verifications were performed for the flood event in September 1990. Because antecedent rainfalls affect initial loss, future researches are required on such effects. The estimation method of major parameters should also be studied for real-time forecasting.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.45-50
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• 2001

The purpose of this study was to estimate of soil loss form hillslope using WEPP(Water Erosion Prediction Project) model. WEPP model was developed for predicting soil erosion and deposition, fundamentally based on soil erosion prediction technology. The model for predicting sediment yields from single storms was applied to a tested watershed. Surface runoff is calculated by kinematic wave equation and infiltration is based on the Green and Ampt equation. Governing equations for sediment continuity, detachment, deposition, shear stress in rills, and transport capacity are presented. Tested watershed has an area of 0.6ha, where the runoff and sediment data were collected. The relative error between predicted and measured runoff was $-16.6{\sim}2.2%$, peak runoff was $-15.6{\sim}2.2%$ and soil loss was $-23.9{\sim}356.5%$.

• Advances in environmental research
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• v.9 no.4
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• pp.251-273
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• 2020

Soil degradation has become a major worldwide environmental problem, particularly in arid and semi-arid climate zones due to irregular rainfall and the intensity of storms that frequently generate heavy flooding. The main objective of this study is the use of geographic information system and remote sensing techniques to quantify and to map the soil losses in the Wadi Saida watershed (624 ㎢) through the revised universal soil loss equation model and a proposed model based on the surface erosive runoff. The results Analysis revealed that the Wadi Saida watershed showed moderate to moderately high soil loss, between 0 and 1000 t/㎢/year. In the northern part of the basin in the region of Sidi Boubkeur and the mountains of Daia; which are characterized by steep slopes, values can reach up to 3000 t/㎢/year. The two models in comparison showed a good correlation with R = 0.95 and RMSE = 0.43; the use of the erosive surface runoff parameter is effective to estimate the rate of soil loss in the watersheds. The problem of soil erosion requires serious interventions, particularly in basins with disturbances and aggressive climatic parameters. Good agricultural practices and forest preservation areas play an important role in soil conservation.

• Journal of The Geomorphological Association of Korea
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• v.28 no.2
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• pp.31-44
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• 2021

Due to recent climate change, continuous soil loss is occurring in the mountainous watershed. The development of geographic information systems allows the spatial simulation of soil loss through hydrological models, but more researches applied to the mountain watershed areas in Korea are needed. In this study, prior to simulating the soil loss characteristics of the mountainous watershed, the field monitoring and the SWAT and GeoWEPP models were used to simulate and analyze the rainfall and runoff characteristics in the mountainous watershed area of Jirisan National Park. As a result of monitoring, runoff showed a characteristic of a rapid response as rainfall increased and decreased. In the simulation runoff results of calibrated SWAT models, R², RMSE and NSE was 0.95, 0.03, and 0.95, respectively. The runoff simulation results of the GeoWEPP model were evaluated as 0.89, 0.30, and 0.83 for R², RMSE, and NSE, respectively. These results, therefore, imply that the runoff simulated through SWAT and GeoWEPP models can be used to simulate soil loss. However, the results of the two models differ from the parameters and base flow of actual main channel, and further consideration is required to increase the model's accuracy.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.2
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• pp.66-71
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• 2005

Soil loss into stream and river by runoff shall be considered for non-point source pollution management as national land conservation. The purpose of this study was to develop the mathematical equation to predict soil loss from inclined uplands of maize cultivation due to the runoff by rainfall which mainly converges on July and August. Soil loss was concentrated on May because of low canopy over an entire field in 2002 and on June and July because of heavy rainfall in 2003. By regression analysis the relation between runoff and soil loss can be represented by a linear equation of y =1.5291x - 3.4933, where y is runoff ($Mg\;ha^{-1}$) and x is soil loss ($kg\;ha^{-1}$). The determination coefficient of this equation was 0.839 (P<0.001). Therefore, the mathematical equation derived from the practical experiment at the inclined upland can be applicable to predict soil loss accompanied by runoff due to periodic rainfall converging on short periods within a couple of months.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.3
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• pp.43-51
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• 1997

The nutrients runoff including nitrogen and phosphorous was investigated to find out the characteristics of nutrient discharge from the slurrigated area using digested animal manure. The results obtained are summarized as follows: 1.The concentrations of T-N, $NH_4$- N, EC, T- P and Cl- were high in flood runoff. 2.The concentration of nutrients by the surface runoff, except for $NO_3$-N, showed a tendency of increasing when the period of dry days before the rain fall was long. And the concentration of N$NO_3$-N increased in the inflow section where subsurface drainage flowed in. 3.The quality of water was generally influenced by the discharge of water quantity from slurrigated area. However the runoff concentration influenced the water quality when it was high enough. 4.To reduce loss of the nutrients and improve the fertilization effect, it is not recommended to apply slurry in rainy season.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.3
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• pp.333-342
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• 2022

Due to climate change, increased heavy rainfalls result in flood damage every year. To investigate the storm-runoff reduction effects of Low Impact Development (LID), this study performed runoff analyses using the U.S. Environmental Protection Agency (EPA) Storm Water Management Model (SWMM) for past and future representative storm events of the Yongdu Rainwater Pumping Station basin. As a result, the infiltration loss for representative future rainfalls increased by 3.17 %, and the surface runoff and peak runoff rate increased significantly by 32.50 %, and 128.77 %, respectively. To reduce the increased surface runoff and peak runoff rates, this study investigated the applicability of LID approaches, including a permeable pavement, green roof, and rain garden, by adjusting the LID parameters and the ratio of installation area. We identified the ranges of LID parameters that decreased peak runoff rate and surface runoff, and increased infiltration. In addition, when the application ratio of permeable pavement, green roof, and rain garden was 2:1:3, best performance was attained, leading to a reduction of peak runoff of 26.85 %, infiltration loss 12.01 %, surface runoff 15.11 %, and storage 509.47 %. Based on analyzing the effect of storm runoff reductions for various return periods, it was found that as the return period increased, the proportion of peak runoff and surface runoff increased and the proportion of infiltration loss and storage decreased.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.986-990
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• 2009

Using artificial rainfall simulator, the soil loss, which is deemed as most cause of muddy water problem among Non-point source(NPS) pollutant, was studied by the analysis of direct runoff flow, groundwater runoff, and groundwater storage properties concerned with rainfall intensity, slope of area, and land cover. The direct runoff showed increasing tendency in both straw covered and bared boxes which are 5%, 10%, and 20% sloped respectively. Also the direct runoff volume from straw covered surface boxes were much lower than bared surface boxes. It's deemed as that the infiltration capacity of straw covered surface boxes were increased, because the surface sealing by fine material of soil surface didn't occurred due to the straw covering. Under the same rainfall intensity and slope condition, 2.4 ${\sim}$ 8.2 times of sediment yield were occurred from bared surface boxes more than straw covered surface boxes. The volume of infiltrated were increased due to straw cover, the direct runoff flow were decreased with decreasing of tractive force in surface. To understand of relationship the rate of direct runoff flow, groundwater runoff, and groundwater storage by the rainfall intensity, slope, and land cover, the statistical test was performed. It shows good relationship between most of factors, expect between the rate of groundwater storage and rainfall intensity.

• Journal of Korea Water Resources Association
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• v.45 no.8
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• pp.795-804
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• 2012

Recently, changes in rainfall intensity and patterns have been causing increasing soil loss worldwide. As a result, the water ecosystem becomes worse and crops yield are reduced with soil loss and nutrient loss with it. Many studies have been proposed to estimate runoff and soil loss to predict or decrease non-point source pollution. Although the USLE has been used for many years in estimating soil losses, the USLE cannot reflect effects on soil loss of changes in rainfall intensity and patterns. The WEPP, physically based model, is capable of predicting soil loss and runoff using various rainfall intensity. In this study, the WEPP model was simulated for sediment yield, runoff and peak runoff using data of 5, 10, 30, 60 minute term rainfall, Huff's method and design rainfall. In case of rainfall interval of 5 minutes and 60 minutes, the sediment and runoff values decreased by 24% and 19%, respectively. The peak rate runoff values decreased by 16% when rainfall interval changed from 5 minutes to 60 minutes, indicating the peak rate runoff values are affected by rainfall intensity to some degrees. As a result of simulating using Huff's method, all values (sediment yield, runoff, peak runoff) were found to be the greatest at third quartile. According to the analysis under various design rainfall conditions (2, 3, 5, 10, 20, 30, 50, 100, 200, 300 years frequency), sediment yield, runoff, and peak runoff of 906.2%, 249.4% and 183.9% were estimated using 2 year to 300 year frequency rainfall data.