• Magazine of the Korean Society of Agricultural Engineers
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• v.24 no.4
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• pp.99-108
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• 1982

This thesis aims to estimate the rainfall runoff from paddy field in a small watershed during irrigation period. When the data observed at the proposed site are not available, the Monthly Runoff Equation of Korean Rivers which was derived from data observed under the following assumptions is used to study the water balance. a. Monthly base flow was assumed as 10. 2mm even if these is no mouthly rainmfall. b. Monthly comsumption of rainfall was ranged from 100 to 2OOmm without relation to the rainfall depth. However, the small watershed which consists mainly of paddy fields encounters severe droughts and accordingly the baseflow is negligible. Under the circumstances the author has developed the following equation called "Flood Irrigation Method for Rainfall Runoff "taking account of the evapotranspiration, precipitation, seepage, less of transportation, etc. R= __ A 7000(1 +F) -5n(n+1)+ (n+1)(Pr-S-Et)] where: R: runoff (ha-m) A: catchment area (ha) F: coefficient of loss (o.o-0. 20) Pr: rainfall (mm) S: seepage Er: evapotranspiration (mm) To verify the above equation, the annual runoff ratio for 28 years was estimated using the Monthly Runoff Equation of Korean Rivers the Flood Irrigation Method and the Complex Hydrograph Method based on meteorological data observed in the Dae Eyeog project area, and comparison was made with data observed in the Han River basin. Consequently, the auther has concluded that the Flood Irrigation Method is more consi- stent with the Complex Hydrograph Method and data observed than the Monthly Runoff Equation of Korean Rivers.

• Journal of Environmental Science International
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• v.20 no.3
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• pp.361-372
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• 2011

This study analyzed the characteristics of stormwater runoff by rainfall type in orchard areas for two years. Effluents were monitored to calculate the EMCs and runoff loads of each pollutant. The runoff characteristics for nonpoint sources from vineyards were also inspected based on independent variables that affect runoff such as rainfall and rainfall intensity. The average runoff loads of each pollutant from vineyard_A and vineyard_B were found as follows: BOD 39.13 mg/$m^2$, COD 112.13 mg/$m^2$, TOC 54.98 mg/$m^2$, SS 1,681.8 mg/$m^2$, TN 18.29 mg/$m^2$, and TP 4.06 mg/$m^2$, which indicates that the COD's runoff load was especially high. The average EMCs from vineyard_A and vineyard_B, which represents the quality of rainfall effluent, were also analyzed: BOD 3.5 mg/L, COD 11.5 mg/L, TOC 5.2 mg/L, SS 211.7 mg/L, TN 1.774 mg/L, and TP 0.324 mg/L. This suggested that the COD, as an indicator of organic pollutants, is high in terms of EMCs as well. As rainfall increased, the EMCs of BOD, COD, TOC and SS kept turning upward. At a point, however, the high rainfall brought about dilution effects and began to push down the EMCs. Higher rainfall intensities led to the increase in the EMCs that displays the convergence of rainfall. Low rainfall intensities also raised pollutant concentrations, although the concentrations themselves were slightly different among pollutants.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.1
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• pp.47-57
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• 2018

This study implemented the rainfall-runoff analysis of the Mekong River basin using the SWAT (Soil and Water Assessment Tool). The runoff analysis was simulated for 2000~2007, and 11 parameters were calibrated using the SUFI-2 (Sequential Uncertainty Fitting-version 2) algorithm of SWAT-CUP (Calibration and Uncertainty Program). As a result of analyzing optimal parameters and sensitivity analysis for 6 cases, the parameter ALPHA_BF was found to be the most sensitive. The reproducibility of the rainfall-runoff results decreased with increasing number of stations used for parameter calibration. The rainfall-runoff simulation results of Case 6 showed that the RMSE of Nong Khai and Kratie stations were 0.97 and 0.9, respectively, and the runoff patterns were relatively accurately simulated. The runoff patterns of Mukdahan and Khong Chaim stations were underestimated during the flood season from 2004 to 2005 but it was acceptable in terms of the overall runoff pattern. These results suggest that the combination of SWAT and SWAT-CUP models is applicable to very large watersheds such as the Mekong for rainfall-runoff simulation, but further studies are needed to reduce the range of modeling uncertainty.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.164-164
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• 2016

Radar rainfall estimates have been widely used in calculating rainfall amount approximately and predicting flood risks. The radar rainfall estimates have a number of error sources such as beam blockage and ground clutter hinder their applications to hydrological flood forecasting. Moreover, it has been reported in paper that those errors are inter-correlated spatially and temporally. Therefore, in the current study, we tested influence about spatio-temporal errors in radar rainfall estimates. Spatio-temporal errors were simulated through a stochastic simulation model, called Multivariate Autoregressive (MAR). For runoff simulation, the Nam River basin in South Korea was used with the distributed rainfall-runoff model, Vflo. The results indicated that spatio-temporal dependent errors caused much higher variations in peak discharge than spatial dependent errors. To further investigate the effect of the magnitude of time correlation among radar errors, different magnitudes of temporal correlations were employed during the rainfall-runoff simulation. The results indicated that strong correlation caused a higher variation in peak discharge. This concluded that the effects on reducing temporal and spatial correlation must be taken in addition to correcting the biases in radar rainfall estimates. Acknowledgements This research was supported by a grant from a Strategic Research Project (Development of Flood Warning and Snowfall Estimation Platform Using Hydrological Radars), which was funded by the Korea Institute of Construction Technology.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.1
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• pp.47-54
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• 2012

This study analyzed influence factors and the correlation among pollutants which affect occurrence of leaked pollution based on the long-term runoff flow and water quality investigation results to understand the characteristics of highway rainfall runoff pollution load. According to the result of correlation analysis on TSS (Total Suspended Solid) concentration, anteceded dry days, rainfall intensity, traffic volume and etc. as major influence factors of highway rainfall runoff pollution loads, the correlations were weak or scarce in most items. These results might be attributed that runoff pollutant concentration changes vary severely on changes of rainfall intensity and rainfall duration within rainfall and it is affected by disturbances of vehicles and street cleaning and etc. as characteristics of the highway. While Cu, Fe and Zn which are discharged with high concentrations out of heavy metals showed high correlation with particulate matter, organic matter(COD), nutrient(TN, TP), Ni and Pb showed relatively low correlation in a correlation evaluation by pollutant. Significant correlation with traffic volumes was not shown and TSS concentration even decreased in accordance with increase of the traffic volume. In the comparison with precedent studies, it was considered necessary additional analysis of the effects of rainfall section analysis, road type, disturbances of surface contaminants by vehicles, rainfall and climate conditions, surrounding terrains etc.

• Journal of Korea Water Resources Association
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• v.52 no.9
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• pp.603-613
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• 2019

This study proposes a method to generate runoff ensemble members using a rainfall-runoff model based on the shot noise process (hereafter the rainfall-runoff model). The proposed method was applied to generate runoff ensemble members for three drainage basins of Daerim 2, Guro 1 and the Jungdong, whose results were then compared with the observed. The parameters of the rainfall-runoff model were estimated using the empirical formulas like the Kerby, Kraven II and Russel, also the concept of modified rational formula. Gamma and exponential distributions were used to generate random numbers of the parameters of the rainfall-runoff model. Especially, the gamma distribution is found to be useful to generate various random numbers depending on the pre-assigned relationship between mean and standard deviation. Comparison between the generated runoff ensemble members and the observed shows that those runoff ensemble members generated using the gamma distribution with its standard deviation twice of the mean properly cover the observed runoff.

• Journal of Environmental Science International
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• v.22 no.12
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• pp.1661-1669
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• 2013

This study conducted a laboratory simulation using artificial and natural rainfall in order to investigate the runoff characteristics of livestock resources through the analysis of the surface runoff water and infiltration water by rainfall intensity and fertilization level. Cattle manure and pig liquid fertilizer was used as livestock resource. As a result of this study, it was observed that the surface runoff occurred over 32 mm/hr rainfall intensity, and flow rate of the surface runoff water and the runoff ratio of contaminant parameters from livestock resource was increased, as rainfall intensity was stronger. With doubled fertilization level, T-N increased in compost and the amount of $COD_{Mn}$ runoff also considerably increased in liquefied fertilizer. In the case of natural rainfall, the runoff ratio of T-P clearly increased in compost and the T-N of final surface runoff ratio in compost and liquefied fertilizer was ranged from 0.13047 to 0.13623 with stronger rainfall intensity.

• Environmental Engineering Research
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• v.15 no.4
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• pp.191-195
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• 2010

This study was carried out to investigate the important factors relating to runoff and pollutant loads in a plot unit located in an agricultural area. Of the precipitation parameters, such as total precipitation, days since last rainfall (ADD, the rainfall was more than 10mm) and average rainfall intensity on runoff, the strongest effect was obtained due to total precipitation, but the rainfall intensity showed a slightly positive correlation. It was expected that both variables, i.e. total precipitation and rainfall intensity, would lead to the generation of greater runoff. In contrast, runoff was negatively correlated with ADD, which is understandable because more infiltration and less runoff would be expected after a long dry period. The TSS load varied greatly, between 75.6 and $5.18{\times}10^4g$, per event. With the exception of TN, the TSS, BOD, COD and TP loads were affected by runoff. The correlations of these items were proportional to the runoff volume, with correlation coefficients (r) greater than 0.70, which are suitable for use as NPS model data. The TSS load showed very good relationships with organics (BOD & COD) and nutrients (TN & TP), with correlation coefficients greater than 0.79. Therefore, the removal of TSS is a promising factor for protecting water basins.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.6
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• pp.3-14
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• 2005

Accurate estimation of the spatial distribution of rainfall is critical to the successful modeling of hydrologic processes. The objective of this study is to evaluate the applicability of spatially distributed rainfall data. Spatially distributed rainfall was calculated using Kriging method and Thiessen method. The application of spatially distributed rainfall was appreciated to the runoff response from the watershed. The results showed that for each method the coefficient of determination for observed hydrograph was $0.92\~0.95$ and root mean square error was $9.78\~10.89$ CMS. Ordinary Kriging method showed more exact results than Simple Kriging, Universal Kriging and Thiessen method, based on comparison of observed and simulated hydrograph. The coefncient of determination for the observed peak flow was 0.9991 and runoff volume was 0.9982. The accuracy of rainfall-runoff prediction depends on the extent of spatial rainfall variability.

• 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.