• Journal of Korea Water Resources Association
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• v.37 no.9
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• pp.745-758
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• 2004

Hydrological models simulate the land phase components of the water cycle and provide a mechanism for evaluating the effects of climatic variation and change on water resources. Evapotranspiration(ET) is a critical process within hydrological models. This study evaluates five different methods for estimating ET in the SLURP(Semi-distributed Land Use Runoff Process)model, in the Yongdam basin. The five ET methods were the FAO Penman-Monteith, Morton CRAE (Complementary Relationship Area Evapotranspiration), the Spittlehouse-Black, the Granger, the Linacre model. We evaluated the five ET models, based on the ability of SLURP model to simulate daily streamflow, and How the five ET methods influence the sensitivity of simulated streamflow to changes in key model parameters and validation SLURP independently for each ET methods. The results showed that the Merton CRAE model had more physical significance and gave better agreement simulated stream flow and recorded flows. It noted that the Morton CRAE model might be more appropriate for the simulation of the actual evapotranspiration in SLURP hydrologic model.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.2 s.17
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• pp.37-44
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• 2005

It reflects well feature of slope that is characteristic of urban river basin of Busan local. In this study, process various hydrological data and basin details data which is collected through basin basis data, hydrological monitoring system(EMS-DEU) and automatic water level equipment(AWS-DEU) for urban flood disaster prevention and use as basin input data of ILLUDAS, SWMM and HEC-HMS in order to examine outflow feature of experiment basin and then use in reservoir design of experiment basin through calibration and verification about HEC-HMS. Inserted design rainfall for 30 years that is design criteria of creek into HEC-HMS and then calculated design floods according to change aspect of the impermeable rate. Capacity of reservoir was determined on the outflow mass curve. Designed detention pond(volume $54,000m^3$) at last outlet upper stream of experiment basin, after designing reservoir. It could be confirmed that the peak flow was reduced resulting from examining outflow aspect. Designing reservoir must decrease outflow of urban areas.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.4
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• pp.1-15
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• 2017

Eutrophication of surface waters is of concern worldwide, because it can result in many undesirable water-quality and ecological problems, such as hypoxic 'dead' zones and harmful algal blooms, both associated with considerable economic costs. In this study, we used LSM (Land Surface Model) to simulate nitrogen in five major rivers in the Southern Korean Peninsula. The main objective of this research was to enhance nitrogen data for input of LM3V model in South Korea. Input data for nitrogen fluxes were categorized into three sections including agriculture fertilizer, livestock manure, atmosphere deposition, biological fixation, and sewage pollutants were used as the nitrogen input. For using LM3V model, the nitrogen input data were regenerated by considering states of agriculture and industry in South Korea at a $1/8^{\circ}$ resolution. Then, we simulated stream/river flows and N loads throughout the entire drainage networks in South Korea at a $1/8^{\circ}$ resolution. By using the same parameters for the entire country ($100,210km^2$), composed of 5 river basins with varying climate and land use, the model simulates spatial (11 sites) and temporal (1999~2010) patterns of flows and nitrate-N loads are resonable by comparing observed flow and nitrate-N loads. The r (Pearson's linear correlation) for water temperature, flow and nitrate-N at river were 080~0.93, 0.62~0.92 and 0.5~0.9 respectively. Based on enhanced N input data and model results, we find that LM3V model as land surface model can be applied in South Korea with interaction of atmosphere and land conditions.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.2
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• pp.137-145
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• 2012

본 연구에서는 2005년부터 2006년까지 충청남도 공주시 반포면에 위치한 봉곡천 유역의 경사지 밭을 포함하고 있는 산지하천에서 유출량, 총인, 총질소를 측정하였고 측정된 자료는 SWAT 모형을 통하여 장기간의 배출부하량 산정을 위해 모형의 보정 및 검정자료로 사용하였다. SWAT 모형의 보정 및 검정결과는 유출량은 일별자료를 이용하여 보정 및 검정을 실시하였다. 그 결과 결정계수 ($R^2$)가 0.80~0.83의 값을 보였으며 일별 T-N, T-P 부하량에 대한 보정 및 검정결과는 결정계수 ($R^2$)가 0.62~0.86의 값을 보였다. 모형의 보정 및 검정을 통해 결정된 최적매개변수를 적용하여 1997년부터 2006년까지 관측된 강우자료로 장기간의 유출량, T-N, T-P 배출부하량에 대한 SWAT 모형 시뮬레이션을 수행하였다. 또한 이를 바탕으로 하여 산지와 밭에 대한 원단위를 산정하였으며, 그 결과 산지에 대한 T-N의 원단위는 3.29 $kg/km^2/day$이었고 T-P에 대한 원단위는 0.15 $kg/km^2/day$로 나타났다. 또한 밭에서의 T-N에 대한 원단위는 11.15 $kg/km^2/day$이었고 T-P에 대한 원단위는 0.70 $kg/km^2/day$로 나타났으며 강우의 시간 및 공간적 변화에 따른 유출량을 고려한 산지와 밭에서의 영양염류 배출부하량을 산정하는데 SWAT모형을 적용하는 것이 타당성이 있는 것으로 판단되었다.

• Water for future
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• v.27 no.4
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• pp.85-94
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• 1994

A Sensitivity analysis on the model parameters involved in the Clark watershed routing method is made to demonstrate the effect of each parameter on the magnitude of 50-year design flood for small urban streams. As for the rainfall parameter the time distribution pattern of design storm was selected. For short duration storms Huff, Yen & Chow and Japanese Central type distributions were selected and the Mononobe distribution of 24-hour design storm was also selected and tested for Clark method application. The effect of SCS runoff curve number for effective rainfall and the methods of subbasin division for time-area curve were also tested. The routing parameter, i.e. the storage constant(K), was found to be the dominating parameter once design storm is selected. A multiple regression formula for K correlated with the drainage area and main channel slope of the basin is proposed for the use in urban stream practice for the determination of design flood by Clark method.

• Water for future
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• v.35 no.5
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• pp.31-43
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• 2002

This study describes results of numerical simulations on river flow response due to global warming. Forecasts of changes in climatic conditions are required to estimate the hydrologic effects of increasing trace gas concentratrions in the atmosphere. However, reliable forecasts of regional climate change are unavailable. In there absense various approaches to the development of scenarios of furture climatic conditions are used. The approach in this study is to prescribe climatic changes for a river basin in a simplified manner. As a rule, such scenarios apecify air temperature increases from $0^{\circ}C$ to $4.0^{\circ}C$ and precipitation change (increase or decrease) in the range of 0% to 15%. On the basis of acceptable supposition of warming scenarios, furute daily stream flow is simulated using rainfall-runoff model in the Andong Dam basin. The numerical experiments have quantitatively revealed the change of discharge at 2010, 2020, 2030 and 1050 for each warming scenarios and compared it with the results for a non-worming scenario.

• Journal of Wetlands Research
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• v.18 no.1
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• pp.94-99
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• 2016

Non-point source control has been issued and intensively studied for the control of water quality in streams and rivers. In this study, non-point source pollutants monitoring was conducted at the end of five small streams which were connected to a main stream in three stages including Phase I (one hr before the rainfall), Phase II (one hr after the rainfall), and Phase III (six hrs after the rainfall). For all five small streams, the concentrations and loading rates of non-point source pollutants significantly increased due to the rainfall. As a result of this, priority control streams and priority pollutants were suggested to prepare for future plans of the non-point source control.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.1
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• pp.99-108
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• 1990

A Synthetic Unit Hydrograph Method was investigated for representation of the effective rainfall-direct runoff hydrograph by using a Geomorphologic Instantaneous Unit Hydrograpb(GIUH) proposed by Gupta et al(1980). The response function of the basin was assumed to be the two-parameter gamma probability density function. The physical parameters of the response function(Nash Model) was determined by using the regression eqs. were parameterized in terms of Horton order ratios and the relations between the basin lag time and time-scale parameter. The capability of the Synthetic Unit Hydrograph to the real basin was tested for the Pyungchang river basin and Wi Stream basin, and its capability to reproduce the hydrologic response was investigate and compared with the Moment Method and the Least Square Method used incomplete gamma function. The representation of the peak flow, the time to peak and the hydrographs the derived Synthetic Unit Hydrograph were tested on some obseved flood data and showed promising, and it was approved to be used for prediction of the ungaged basins.

• Journal of Ecology and Environment
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• v.38 no.2
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• pp.145-156
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• 2015

This study was based on water quality data of the Lake Doam watershed, monitored from 2010 to 2013 at eight different sites with multiple physiochemical parameters. The dataset was divided into two sub-datasets, namely, non-rainy and rainy. Principal component analysis (PCA) and factor analysis (FA) techniques were applied to evaluate seasonal correlations of water quality parameters and extract the most significant parameters influencing stream water quality. The first five principal components identified by PCA techniques explained greater than 80% of the total variance for both datasets. PCA and FA results indicated that total nitrogen, nitrate nitrogen, total phosphorus, and dissolved inorganic phosphorus were the most significant parameters under the non-rainy condition. This indicates that organic and inorganic pollutants loads in the streams can be related to discharges from point sources (domestic discharges) and non-point sources (agriculture, forest) of pollution. During the rainy period, turbidity, suspended solids, nitrate nitrogen, and dissolved inorganic phosphorus were identified as the most significant parameters. Physical parameters, suspended solids, and turbidity, are related to soil erosion and runoff from the basin. Organic and inorganic pollutants during the rainy period can be linked to decayed matters, manure, and inorganic fertilizers used in farming. Thus, the results of this study suggest that principal component analysis techniques are useful for analysis and interpretation of data and identification of pollution factors, which are valuable for understanding seasonal variations in water quality for effective management.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.975-985
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• 2013

In this research, the integrated modeling system by coupling of a watershed model, a reservoir model, and a river model has been constructed in Doam reservoir watershed. Because of domestic climate characteristics, it is inevitable to construct the dam for control of flood, water use, and power production due to the heavy rain in the summer. Especially, when the dam is constructed on the stream for these kinds of purpose, it is necessary to consider this region as one watershed and also to make the integrated system for simulation and management. In this study, SWAT model was constructed for watershed modeling and EFDC-WASP model was constructed for simulating the hydrodynamic and water quality of the reservoir and the downstream in Doam dam watershed. Also, the water quality improvement equipment for demonstration was applied in the upstream part of Doam reservoir, which shows the applicability of the developed integrated modeling system.