• Korean Journal of Soil Science and Fertilizer
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• v.49 no.6
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• pp.669-676
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• 2016

A field study was conducted to determine the runoff loss of N and P in small scale of red pepper field plots (10% slope), consisting of three different plots with black polyethylene vinyl mulching (mulching), ridge without mulching (ridge), and flat without ridge and mulching (flat). Composted manure and urea as a basal application were applied at rates of $20MT\;ha^{-1}$ and $93kg\;N\;ha^{-1}$, respectively. Urea at $189kg\;N\;ha^{-1}$ and fused phosphate at $67kg\;P_2O_5\;ha^{-1}$ were additionally applied on June 25 with different fertilization methods, broadcast application in flat plot and hole injection in ridge and mulching plots. Plant uptake of N and P was positively correlated with their respective concentrations in surface soil: mulching > ridge > flat plots. The runoff loss by soil erosion was higher in flat plot than ridge and mulching plot with contour line. Nitrate loss by the runoff water had no significant differences among three surface management practices, but the higher average value in ridge and mulching plots than flat plot. Especially, the flat plot had no phosphate loss during summer season. This is probably due to low labile P content in surface soil of flat plot. In the summation of soil and water loss, flat plot was higher in N and P loss than ridge and mulching plot with contour line. Nevertheless, the nitrate and phosphate loss by runoff water could be more important for non-point source management because the water could meet the river easier than eroded soil because of re-deposition around slope land.

• Journal of Korean Society on Water Environment
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• v.29 no.5
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• pp.681-690
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• 2013

Watershed models have been increasingly used to support an integrated management of land and water, non-point source pollutants, and implement total daily maximum load policy. However, these models demand a great amount of input data, process parameters, a proper calibration, and sometimes result in significant uncertainty in the simulation results. For this reason, uncertainty analysis is necessary to minimize the risk in the use of the models for an important decision making. The objectives of this study were to evaluate three different uncertainty analysis algorithms (SUFI-2: Sequential Uncertainty Fitting-Ver.2, GLUE: Generalized Likelihood Uncertainty Estimation, ParaSol: Parameter Solution) that used to analyze the sensitivity of the SWAT(Soil and Water Assessment Tool) parameters and auto-calibration in a watershed, evaluate the uncertainties on the simulations of runoff and sediment load, and suggest alternatives to reduce the uncertainty. The results confirmed that the parameters which are most sensitive to runoff and sediment simulations were consistent in three algorithms although the order of importance is slightly different. In addition, there was no significant difference in the performance of auto-calibration results for runoff simulations. On the other hand, sediment calibration results showed less modeling efficiency compared to runoff simulations, which is probably due to the lack of measurement data. It is obvious that the parameter uncertainty in the sediment simulation is much grater than that in the runoff simulation. To decrease the uncertainty of SWAT simulations, it is recommended to estimate feasible ranges of model parameters, and obtain sufficient and reliable measurement data for the study site.

• Journal of Korea Water Resources Association
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• v.33 no.4
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• pp.393-405
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• 2000

Monthly runoff was estimated using TOPMODEL which simulates ground water movement as well as surface runoff in the area of catchment. SAYUN dam which is being operated by Korea Water Resources Corporation was selected for the study, and the topographic factors of the watershed were analyzed using 1/5,000 digital map and GIS software(Arc/Info). The comparison shows good agreement between observed monthly runoff and the computation results simulated by using TOPMODEL. The catchment area of SAYUN dam was modeled by using various grid sizes in order to check the sensitivity of grid size, and the grid size of 180m was found most proper among 6 different sizes. TOPMODEL was also found superior to the existing monthly runoff models such as Kajiyama, KRIHS and Tank. Because the model requires limited number of parameters and considers topographic aspects, it is reckoned to be very useful for practical use.

• 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.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.3
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• pp.229-235
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• 2021

Globally, due to climate change and urbanization, problems with water cycle destruction in urban areas frequently occur. In order to solve this problem, LID technique is being actively conducted the application in urban and research. In this study, some areas of the new city located in Busan was constructed using a widely used SWMM model to verify the effectiveness of the LID technique. This is to present a plan to maximize the efficiency of urban water cycle of the stormwater management target figure and the LID scale calculation method. In addition, the efficiency of runoff reduction using stormwater storage basin was analyzed in urban development projects. By calculating the scale of customized LID for each sub basin, the amount of runoff and peak runoff after LID application was reduced by 86.8 % and 69.5 %, respectively. Depending on the application of the stormwater storage basin, the reduction effect of peak runoff from 0.5 m³/s to 4.9 m³/s and delay effect of 8 minutes to 10 minutes was shown.

• Korean Journal of Environmental Agriculture
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• v.38 no.4
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• pp.307-313
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• 2019

BACKGROUND: An intensive farming system may be of the most important source for agricultural non-point source (NPS) pollution, which is a major concern for agricultural water management in South Korea. Various management practices have therefore been applied to reduce NPS loads from upland fields. This study presents performances of sediment trap for reducing NPS and soil loss from rainfall runoff in cropland. METHODS AND RESULTS: In 2018 and 2019, three sediment traps (L1.5 m × W1.0 m × D0.5 m = 0.75 ㎥) and their controls were established in the end of sloped (ca. 3%) upland field planted with maize crops. Over the seasons, runoff water was monitored, collected, and analyzed at every runoff. Soils deposited in sediment traps were collected and weighed at the season end. Sediment traps reduced runoff amount (p<0.05) and NPS concentrations, though the decreased NPS concentrations were not always statistically significant. In addition, sediment traps had a significant prevention effect on soil loss from rainfall runoff in a sloped cropland. CONCLUSION: The results suggest that the sediment trap could be a powerful and the best management practice to reduce NPS pollution and soil loss in a sloped upland field.

• Journal of Korean Society on Water Environment
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• v.26 no.6
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• pp.943-947
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• 2010

Runoff ratio of paddy fields for the application of Event Mean Concentration (EMC) method was studied. To measure actual runoff ratio of paddy fields, a field monitoring was conducted for 2008 ~ 2009 period. Long-term rainfall data of four cities in major river basins were analyzed and weighting factors were developed to consider temporal and spatial variation of rainfall distribution of Korean peninsula. The observed runoff ratio ranged 0.00 ~ 1.20 and arithmetic mean were 0.25, respectively. However, the representative runoff ratio for paddy fields was determined as 0.41 according to the method suggested by National Institute of Environmental Research (NIER).

• Journal of Environmental Science International
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• v.25 no.7
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• pp.1007-1016
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• 2016

Environmental policy implementation has been strengthened to protect the source waters in Korea and to improve their water quality. Increasing of non-point source caused water quality problem continuously. Research on runoff from forests, which occupy over 65% of the land in korea, is insufficient, and studies on the characteristics and influences of storm runoff are necessary. In this study, we chose to compare the effects of land use in the form of two types of forest distribution and then gathered data on storm characteristics and runoff properties during rainfall events in these areas. Furthermore, the significance and influences of the discharges were analyzed through correlation analysis, and multilateral runoff characteristics were examined by deducing a formula through $COD_{Mn}$ and TOC regression analysis. At two forest points, for which the basin areas differed from each other, flow changed according to storm quantity and intensity. The peak discharge at point A, where the basin area was big, was high, whereas water-quality fundamental items (BOD, $COD_{Mn}$, and SS) and TOC density were high at point B where the slope and storm intensity were high. Effects of dissolved organic matter were determined through correlation analysis, and the regression formulas for $COD_{Mn}$ and TOC were deduced by regression analysis. It is expected that the data from this study could be useful as basic information in establishing forest management measures.

• Water for future
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• v.26 no.3
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• pp.125-135
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• 1993

This study was conducted for two purposes. The first was the selection of the proper model for the urban runoff, and NPS(non-point source) loads and the second was the adjustment of the selected model through the calibration and the verification of the observed data on an urban drainage basin. The selected model for this study was the Storm Water Management Model(SWMM) developed and maintained by the US Environmental Protection Agency(EPA). In particular, the Runoff Block for the surface discharge and the Transport Block for the flow routing was used. The study basin is Youngdu basin, which is a typical developed urban drainage basin. The four rainfall events for the runoff and the two for the four NPS pollutants(SS, BOD, COD and TN) were used for the calibration and the estimation of the model parameters. This study performed the calibration with regard to the peak discharge, the time to peak discharge, the volume and the relative error for three items. It was shown that SWMM can successfully be used for the prediction of the runoff and the NPS pollutants discharge. The result of this study can be used as the basis for the analysis of the correlation between the runoff and the NPS pollutants discharges, and the analysis of the mass balance with the monthly and annual NPS loads in an urban drainage basin.

• Journal of Korea Water Resources Association
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• v.42 no.10
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• pp.809-824
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• 2009

Hydrological system forecasting, which is the short term runoff historical data during the limited period in dam site, is a conditional precedent of hydrological persistence by stochastic analysis. We have forecasted the monthly hydrological system from Andong dam basin data that is the rainfall, evaporation, and runoff, using the seasonal ARIMA (autoregressive integrated moving average) model. Also we have conducted long term runoff simulations through the forecasted results of TANK model and ARIMA+TANK model. The results of analysis have been concurred to the observation data, and it has been considered for application to possibility on the stochastic model for dam inflow forecasting. Thus, the method presented in this study suggests a help to water resource mid- and long-term strategy establishment to application for runoff simulations through the forecasting variables of hydrological time series on the relatively short holding runoff data in an object basins.