• KCID journal
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• v.18 no.2
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• pp.3-14
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• 2011

Increased impervious surfaces alter stream hydrology resulting in lower flows during droughts and higher peak flows during floods. Not only urban area but also rural area has been expanded impervious surfaces because of increasing of greenhouses. The main objective of this study was to evaluate the performance of the AnnAGNPS (Annualized Non-Point Source Pollution Model) on the surface runoff characteristics of the Daejeon-Stream watershed, and to predict the hydrological effects due to increasing of impervious surfaces. The model parameters were obtained from the geographical information system (GIS) databases, and additional parameters calibrated with the observed data. The model was calibrated by using 2004 of the runoff data and validated by using 2002 data obtained from WAMIS (Water Management Information System) to compare the simulated results for the study watershed. R2 values and efficiency index (EI) between observed and simulated runoff were 0.78 and 0.80, respectively at the calibration period. In this study, expanding of impervious surfaces such as greenhouses caused increasing of surface runoff, but caused decreasing of total nitrogen and total phosphorus loads.

• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.3
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• pp.92-100
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• 1996

In order to control the water quality in rivers or lakes, it is needed to evaluate accurate amount of pollutant loadings from watersheds. The daily pollutant loadings were simulated using the pollutant loading calculation model which was composed of mathematical equations superimposed on the TANK model. The calibration of runoff and pollutant loading parameters were carried out with observed data, using a trial-and-error method. In addition, the proposed model was applied to evaluate its applicability for the representative watershed, the Bokha river watershed, Icheon city, Korea. The parameters of SS and T-P showed large values in the first tank while T-N showed large in the second tank. As a result of simulating the daily pollutant loadings by the pollutant loading calculation model, all of SS, T-N and T-P loadings were increased or decreased according to the amount of runoff discharge. Especially, it was apparent that SS and T-P loadings were significantly influenced by the runoff variation when it was rain. These results could partly explain that SS and T-P would occur mainly from the surface runoff while T-N would occur from both surface and subsurface flow.

• 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 Korean Society of Water and Wastewater
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• v.26 no.1
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• pp.55-68
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• 2012

Impervious surface increase due to urbanization, one of the leading causes of pavement increased the runoff coefficient, peak flow, and reducing the infiltration flow and thereby causing flooding and river erosion is occurring in aquatic ecosystems are known to impair. This study aimed to classify use type of detailed land into the road, reststop, tollgates and etc. focused on major domestic highways, to understand the characteristics of rainfall runoff pollutants and to calculate applicable unit pollution load. Because of high runoff coefficient and short travel time to drainage. first flush occurred clearly. Average EMCs of runoff in the highway was investigated as TSS 108.47 mg / L, COD 28.16 mg / L, BOD 13.61 mg / L, TN 6.38 mg / L, TP 0.03 mg / L, Cu 118.17 ${\mu}g$ / L, Pb 345.3 ${\mu}g$ / L, Zn 349.47 ${\mu}g$ / L. Unit pollution loads calculated by detailed land use area of highways based on average annual rainfall, EMCs, applicable basin areas and etc. were 46.6 kg/km2/day of BOD, 1.4 kg/km2/day of TP, 8.81 kg / km2/day of TN and these were BOD 50.8%, TP 66.7%, TN 64.4%in comparison of the unit pollution loads which applies fallow land standards of the TMDL(Total Maximum Daily Load). It was considered that discharged loads can be excessively calculated in case highway non-point management plans based on unit pollution load of the current land standard.

• Journal of Environmental Science International
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• v.5 no.5
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• pp.585-592
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• 1996

Trifluralin (2, 6-dinitro-N, N-dipropyl-4- (trifluormethyl) benzenamine) was applied preemergent to soybean in plots drained or nondrained, in louisiana. Plots 14.6 ha were arranged to give 1683 g/ha of trifluralin. The half life of trifluralin in the top 15 cm of soil was 42.6 darts and f6.0 days in nondrained plot and drained plot, respectively. The concentrations of trifluralin in surface runoff water and subsurface runoff water were 0.62 ng/ml-0.02 ng/ml and 11.06 ng/ml-0.02 ng/ml, respectively. The concentration of trifluralin in runoff water was smaller than 2 ng/ml for trifluralin of U.S. Environmental Protection Agency advisory. Total loss of trifluralin in runoff water was 0.021 % of applied amount at drained plots during three month after application. Trifluralin was moved hardly in the water. Subsurface drainage -reduced trifluralin losses because concentration of trifluralin in the subsurface runoff water in drained fields was low.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.147-155
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• 1993

An urban runoff model is proposed in this study, which is composed of a surface runoff model and a channel routing model. ILLUDAS is selected as the best fit model for the surface runoff computation, and the dynamic wave model using weighted four-point implicit finite difference scheme is used to perform the channel routing. The 3rd Seongbook bridge basin located in Seoul is selected as the test basin for the proposed model, and the rainfall-runoff data are collected to calibrate and verify the urban runoff model. The computed results by this model showed the fair accuracy when compared with the observed hydrographs. So the model proposed in this study could be used to compute the urban river flow as well as the outflow from the urban drainage area.

• Journal of Korea Water Resources Association
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• v.35 no.2
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• pp.125-136
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• 2002

The effects of the temporal scale of input hydrological data on runoff simulation have been studied using hydrological data with various time scales. TOPMODEL has been employed to explores these effects. The Genetic a1gorithm was used to calibrate model Parameters. The results of sensitivity analysis in various time scales provide the insight of parameter space for TOPMODEL operation of different time scale. The variation of temporal scale of input hydrological data appeared to have significant impacts on the model efficiency, average water table depth, the ratio of the surface runoff to the total runoff and the calibrated parameters. Generally, the longer the time scale, the more surface runoff and the less average water table death were calculated. It is found that the impact of lime scale to runoff simulation results from the structure of TOPMODEL and the hydrographic morphology.

• Journal of Wetlands Research
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• v.11 no.1
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• pp.91-97
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• 2009

The fowls manure is using as fertilizers for farmland because of enough nutrients. However, excess nutrients can be washed off during a storm and affected on nearby waterbodies. In this paper, the runoff characteristics from farmland were studied to determine the washoff mass. A lab-scale reactor was designed to estimate the surface runoff and infiltration rates according to the rainfall intensity. Surface runoff water did not occur at 10mm/hr rainfall intensity, but some runoff occurred at 20mm/hr rainfall intensity. At 32.4mm/hr rainfall intensity, it shows the highest pollutant concentrations such as 686mg/L for $BOD_5$ and at 630mg/L $COD_{Mn}$. The pollutant as based on fowls manure compost was highly washed-off by subsurface water at 32.4mm/hr rainfall intensity, however the concentration was largely decreased at 43.2mm/hr rainfall intensity. The summary of the results is that the highest wash-off concentrations value shows at 32.4mm/hr rainfall intensity for $BOD_5$ and at 67.1mm/hr for T-N and T-P.

• Magazine of the Korean Society of Agricultural Engineers
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• v.35 no.1
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• pp.29-39
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• 1993

A model for estimating daily effective rainfall of upland crops was developed. The infiltration process was described by Green-Ampt infiltration model developed by Chu(1978). The model considers delayed surface ponding and surface detention storage under a uniform soil profile. The Green-Ampt parameters, that is, average hydraulic conductivity and average capillary pressure head on a sandy loam soil were determined from field experiment using Air-entry permeameter developed by Bouwer(1966). The model was verified by comparing measured and simulated surface runoff. The ratios of effective rainfall to total rainfall for red pepper, soybean, sesame and Chinese cabbage were evaluated using Borg's root growth model( 1986) respectively. The followings are a summary of this study results; 1.In a sandy loam soil average hydraulic conductivity was 3.28cm/hr and average capillary pressure head was 3.00cm. 2.The root growth of upland crops could be expressed by Borg's root growth model successively. 3.The measured and simulated surface runoff was agreed well with each other. 4.As the rainfall amount was increased, the ratio of effective rainfall to total rainfall was decreased exponentially till a certain growing period.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.5
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• pp.55-67
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• 2018

The objectives of this study were to monitor organic farming upland compared with conventional upland field and to evaluate nutrient loads reduction of surface cover effect with long-term historical climate data. APEX(Agricultural Policy Environmental eXtender) model was validated with experimental data and used for assessing surface cover scenarios for 30-year simulation periods. The validated values of RMSE(Root Mean Square Error), RMAE(Root Mean Absolute Error), $R^2$ and E(Nash-Sutcliffe efficiency) for runoff were 1.17-1.37 mm/day, 0.28-0.45 mm/day, 0.88-0.90 and 0.82-0.94 in two treatments, respectively. Those for water quality (nitrogen) were 0.05-0.16 kg/ha, 0.52-0.75 kg/ha, 0.67-0.72 and 0.32-0.70 in two treatments, respectively, and therefore the validated model showed good agreement with the observed runoff and nitrogen load for the study period. When decreasing the surface cover rate of organic farming field to 75%, 50%, 25%, and 0% (conventional field), average annual runoff increased by 7%, 15%, 23% and 31%, respectively. Under same condition of decreasing the surface cover rate, average annual nitrogen loads increased by 1.4 times, 1.7 times, 2.0 times, and 2.3 times compared with organic farming field, respectively. This study showed that it is possible to present an appropriate surface cover ratio to maintain conventional production and minimize nonpoint sources pollution for organic farming system, although long-term monitoring is needed to determine its effects on environmental concerns, crop competition, and other uncertainty.