• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.848-854
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• 2011

The objective of this research was to experimentally test the effect of rice straw mats on the reduction of runoff, sediment and discharge under a laboratory scale with different rainfall intensity and slopes. We used the small runoff plots of $1m{\times}1m{\times}0.65m$ ($L{\times}W{\times}H$) in size were filled with loamy sand. Experimental treatments were bare (control), rice straw mats + PAM(SP), rice straw mats + PAM + sawdust(SPS) and rice straw mats + PAM + rice husks(SPR); slope of 10% or 20%; and rainfall intensity of 30 or 60 mm/hr. Runoff volume and coefficient from covered plots were significantly lower than those from control plots. Under the 30 mm/hr and 10% simulations, average runoff coefficient of covered plots decreased more than 92%. Under 60 mm/hr and 20% simulations, the ratios were between 39.8~58.1%. Under the condition of 30 mm/hr rainfall and 10% slope, sediment discharge from covered plots was practically zero. And at 20% plots, sediment reduction ratio was more than 95%. Under the condition of 60 mm/hr rainfall, sediment reduction ratio of 10 and 20% plots ranged between 86.3~95.3% and between 79.8~86.5%, respectively. The differences in initial runoff time, runoff and sediment discharge among different cover materials were not significant. Rainfall intensity showed higher impact on initial runoff time, runoff, and sediment discharge than slope. It was also shown that even if runoff reduction by surface cover were low, sediment discharge reduction could be very significant and contribute to improve the water quality of streams in sloping agricultural regions. It was concluded that the use of straw mat and PAM on sloping agricultural fields could reduce soil erosion and muddy runoff significantly and help improve the water quality and aquatic ecosystem in receiving waters.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.422-425
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• 2004

To understand runoff Phenomena in Jeju island, some streams are monitored automatically about stream stage, and water quality in Jeju Provincial Water Resources Management Office. Rating curves for stream discharge are reviewed. Stream stages respond very quick to some rainfall events, and parameters influencing runoff phenomena such as landuse, soil condition, preconditoned rainfall, and vegetables will be studied. A few thousand to ten thousand ml/day are estimated from 6 permanent streams in Jeju island.

• Journal of Korean Society on Water Environment
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• v.22 no.4
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• pp.648-657
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• 2006

Characteristics of water quantity and quality of the Anyangcheon were analyzed through many field measurements and the distributed hydrologic simulation model, Soil and Water Assessment Tool (SWAT). Event mean concentrations (EMCs) and baseflow mean concentrations were calculated from the data and the daily runoff were simulated by SWAT. The runoff was divided into the direct runoff and the baseflow. Using those values and quantity and quality data of release from the wastewater treatment plant (WWPT), unit loads of BOD, COD, SS, $NO_2-N$, $NO_3-N$, $NH_3-N$, and Dis-P were derived. EMCs of BOD and SS were even higher than the baseflow mean concentrations. The total runoff from October to April (7 months) of 2004 was just 13.5%, since the rainfall usually is concentrated in summer season. Futhermore BOD and SS were loaded during the event by 50.9% and 70.9%, respectively and over three quarters of total COD, $NO_2-N$, $NO_3-N$, $NH_3-N$, and Dis-P were flowed into the Anyangcheon during the remaining period. Therefore, the efficiency of WWPT for COD, $NO_2-N$, $NO_3-N$, $NH_3-N$, and Dis-P should be intensified from Oct. to Apr. and the runoff quality management of BOD and SS should be planned during the summer season.

• Journal of Korea Water Resources Association
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• v.37 no.7
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• pp.589-598
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• 2004

From the continuous long-term rainfall-runoff standpoint, the urbanization within a watershed causes land use change due to the increase in impervious areas, the addition of manmade structures, and the changes in river environment. Therefore, rainfall-runoff characteristics changes drastically after the urbanization. Due to these reasons, there exists the demand for rainfall-runoff simulation model that can quantitatively evaluate the components of hydrologic cycle including surface runoff, river flow, and groundwater by considering urban watershed characteristics as well as natural runoff characteristics. In this study, continuous long-term rainfall-runoff simulation model SWAT-SWMM is developed by coupling semi-distributed continuous long-term rainfall-runoff simulation model SWAT with RUNOFF block of SWMM, which is frequently used in the runoff analysis of urban areas in order to consider urban watershed as well as natural watershed. The coupling of SWAT and SWMM is described with emphasis on the coupling scheme, model limitations, and the schematics of coupled model.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.6
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• pp.29-37
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• 2012

This study was carried out to runoff characteristics in an upland livestock manure compost. Irrigation, runoff and water quality data in the upland were analyzed periodically from May to November in 2011. The observed amount of rainfall, irrigation, runoff for the experimental upland during the investigation period were 1,299.7 mm, 32.0 mm, and 340.7 mm, respectively. The concentrations of T-N in compost and non-compost upland during study period were ranged from 2.09 mg/L to 6.66 mg/L and from 1.99 mg/L to 6.01 mg/L, respectively. which was generally higher than the quality standard of agricultural water (1.0 mg/L). The concentrations of T-P in compost and non-compost upland during study period were ranged from 0.069 mg/L to 0.525 mg/L and from 0.018 mg/L to 0.152 mg/L, respectively. The runoff pollutants loadings of T-N and T-P in compost upland were 10.05 kg/ha and 0.56 kg/ha, respectively. The runoff pollutants loadings of T-N and T-P in non-compost upland were 9.09 kg/ha and 0.26 kg/ha, respectively. The runoff pollutants loadings in T-N and T-P from this study were much lower values than the pollutant loadings of T-N and T-P from the upland published by the others studies. Runoff pollution loadings due to the upland field in order to identify the characteristics of various crops, farming methods and a variety of targets taking into account regional characteristics by conducting continuous monitoring runoff load estimate will be required.

• Journal of Korea Water Resources Association
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• v.41 no.6
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• pp.565-574
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• 2008

Fire-enhanced soil hydrophobicity often increases runoff and erosion in the mountain hillslope following severe wildfires. Estimation techniques for WEPP's parameters were studied in burnt mountain slopes. In burnt mountain slopes, the model over-predicted runoff in the small runoff and under-predicted runoff in the great runoff, and in the lower sediment runoff it had a tendency to over-predict soil loss. The effective hydraulic conductivity was most sensitive in the WEPP's runoff and its sediment runoff was mainly effected by the effective hydraulic conductivity, initial saturation, rill erodibility, and interrill erodibility. To improve the applicability of the WEPP, the adjustment coefficient of effective hydraulic conductivity was defined for runoff and the adjustment coefficient of rill erodibility and interrill erodibility was presented for sediment runoff. The adjustment coefficient of effective hydraulic conductivity in wildfire mountain slopes increased with maximum rainfall intensity of single storm and the vegetation height index. The adjustment coefficients of rill erodibility depended on soil components of size distribution curve and total rainfall depths in single storm. The adjustment coefficients of interrill erodibility decreased with increases of maximum rainfall intensity and vegetation height index. These results may be used in the application of WEPP model for wildfire mountain slopes.

• Journal of Korea Water Resources Association
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• v.42 no.2
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• pp.171-176
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• 2009

This study proposes an experimental formula for cumulative runoff analysis in building roof for on-site rainwater management. We can not find an appropriate method for roof runoff analysis because of its small area scale. A new runoff equation formula for rainfall depth(D) and cumulative runoff volume(V) is developed on roof runoff conditions. Reliability of the formula is verified with field experimental runoff monitoring for two years in two buildings of rainwater management system. This experimental runoff formula can root the cumulative runoff volume from roof area and rainfall depth, then develop reasonable inflow condition for rainwater retention tank design.

• Journal of Korea Water Resources Association
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• v.48 no.6
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• pp.439-449
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• 2015

In this study, reliable future runoff projections based on RCPs for Yongdam dam watershed was performed using SWAT model, which was validated by k-fold cross validation method, and investigated the factors that cause the differences with respect to runoff projections between this study and previous studies. As a result, annual average runoff compared to baseline runoff would increase 17.7% and 26.1% in 2040s and 2080s respectively under RCP8.5 scenario, and 21.9% and 44.6% in 2040s and 2080s respectively under RCP4.5 scenario. Comparing the results to previous studies, minimum and maximum differences between runoff projections over different studies were 10.3% and 53.2%, even though runoff was projected by the same rainfall-runoff model. SWAT model has 27 parameters and physically based complex structure, so it tends to make different results by the model users' setting. In the future, it is necessary to reduce the cause of difference to generate standard runoff scenarios.

• Korean Journal of Hydrosciences
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• v.5
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• pp.99-114
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• 1994

Three purposes of this study are as follows : The first was the development of the extension method for the limited data observed in an urban drainage basin. The second was the analysis of the correlation between storm water runoff and NPS(non-point source) Pollutant discharge. The last was the calculation of the monthly and annual specific NPS loads using the established correlation. The selected model was the SWMM(Storm Water Management Model) developed by the US EPA(Environmental Protection Agency). As a result of this study, the best correlation between storm water runoff and NPS pollutants discharge was produced by the nonlinear correlation between runoff rate(mm/hr) and specific loads rate(kg/ha) for all pollutants studied : SS, COD, BOD, and TN. The best correlation through the analysis based on evently total mass was made by the linear correlation between the by the nonlinear correlation for CASE2. The NPS annual specific loads for the urban basin studed were 4,993 kg/ha/year for SS, 775 kg/ha/year for BOD, 3,094 kg/ha/year for COD, 257 kg/ha/year for TN, respectively. And the proportion of the NPS annual specific loads to the total annual specific loads were 41 % for SS, 13 % for BOD, 29 % for COD, and 21 % for TN.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.619-622
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• 2003

The concentrations of nutrients in precipitation increased slightly from May to June and did not change afterwards. Regarding irrigation water, the nutrient concentrations were high in the early stage of rice growth but decreased during the period of mid-June to mid-July. The concentration of Tot-N in runoff water increased significantly during the period of fertilizer application (basal, tillering, and panicle fertilization) and then decreased. The concentrations of Tot-N in runoff water ranged from 0.4 to 39.8mg/L (average of 5.9mg/L). The concentration of Tot-P in runoff water ranged from 0.0004 to 0.2084mg/L (average of 0.055mg/L). The Tot-P concentrations were high only at the early stage of rice growth after fertilizer application and did not change afterwards.