• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.3
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• pp.94-102
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• 2003

A hydrologic and water quality monitoring network were established in the Balkan-reservoir watershed, which has 29.79 $km^2$ in size, to analyze the characteristics of pollutant loading from an agricultural small watershed. Soil type, land use, hydrologic soil group, population and livestock were also surveyed to make clear the pollutant sources and to calculate the pollutant loadings by the unit loading factor method which was proposed by the Ministry of Environment. From the 5-year hydrologic monitoring results, sub-watersheds located in the upstream of the reservoirs showed higher average runoff ratio. The calculated daily pollutant loadings by the unit loading factor method from HP#2 sub-watershed in the downstream of Balkan reservoir, were much greater than observed.

• Magazine of the Korean Society of Agricultural Engineers
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• v.31 no.1
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• pp.45-57
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• 1989

The hydrologic model FESHM was introduced and its applicability was investigated in an attempt to analyze the rainfall-runoff relationships of urban small watersheds and to hereafter predict the envi-ronmental changes. Basic data on rainfall, water level, geomorphological characterisitics and land use were obtained from Yeonwha stream watershed located in Chonju-si Dukjin-dong. WL-5 for simulation o subshed WS# 1(136.7 ha) with urban district and WL-1 for total watershed WS#5 (278.78 ha) we'e selected as gaging points. The main results gained through applications were summarized as follows. 1. Direct runoff ratio caalculated from a simple separation method for WS#5 WS# 1 was 2O~39%, 38~62%, respectively. 2. Simulations for the runoff estimation were carried out for each watershed using 5 rainfall events, the simulation errors had the range of 2~ 30%, O~ 63% and O 120 minutes for the runoff volume, peak flow and peak time, respectively. 3. The effect of landuse change by urbanization was tested to WS# 1, runoff volume before development was estimated as from tenth to twentieth against after development.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.384-389
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• 2000

A artificial neural network model was developed to analyze and forecast the flow fluctuation at small streams in the Balan watershed. Backpropagation neural networks were found to perform very well in forecasting daily streamflows. In order to deal with slow convergence and an appropriate structure, two algorithms were proposed for speeding up the convergence of the backpropagation method, and the Bayesian Information Criterion(BIC) was proposed for obtaining the optimal number of hidden nodes. From simulations using daily flows at the HS#3 watershed of the Balan Watershed Project, which is 412,5 ㏊ in size and relatively steep in landscape, it was found that those algorithms perform satisfactorily.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.295-299
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• 2001

To protect the flooding damages in Medium and Small watershed, it needs to set up flood warning system and develope Flood forecasting Model in real-time basis for medium and small watershed. In this study, it was able to minimize the error range between forecasted flood inflow and actual flood inflow, and forecast accurately the flood discharge some hours in advance by using simplex method recursively for the determination of the best parameters of RETFLO model. The result of RETFLO performance applied to several storm of Yugu river during 3 past years was very good with relative errors of 10% for comparison of total runoff volume and with one hour delayed peak time.

• Journal of Korean Society of Rural Planning
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• v.7 no.1 s.13
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• pp.3-13
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• 2001

In an effort to effectively manage and evaluate a water environment at a small watershed, a decision support system for a water environment management and evaluation has been developed. This paper described the overall features and functions of the water environment management and evaluation systems (WEMES) for environmental management, conservation, and evaluation at a small watershed. WEMES consisted of fore subsystems: data, simulation model, evaluation model, and user interface. Each of the systems were briefly described. And special features like simulation and evaluation models were also introduced.

• Journal of Korean Society of Forest Science
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• v.103 no.3
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• pp.383-391
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• 2014

Long-term changes in the hydrological characteristics of a small forest watershed were examined using a master baseflow recession curve and the measured rainfall-runoff data from the experimental forest watershed in the measured years 2003-2011. The results of the study showed that the recession coefficient of direct runoff was lower than that of baseflow. In small forested watershed, the direct flow was lower than that of large scale watershed, flow due to its shorter period of occurrence. And baseflow was similar to large scale watershed's. A regression equation $y=0.7528e^{-0.022x}$($R^2=0.8938$, range 0.3~0.8 mm) was obtained using the master baseflow recession curve for the study period and the recession coefficient was calculated as K = 0.978. Changes between master baseflow recession curve and runoff showed great association and relevance such as increasing runoff was associated with the gentle slope of master baseflow recession curve and decreasing runoff was associated with the slope of master baseflow recession curve contrary. In the later years of the study period, the slope of the master baseflow recession curve appreciably became more gentle due to increases in baseflow. This suggests that the forested experimental watershed exhibit improved structural functioning of normal flood control and reduced occurrence of water shortage problems.

• Journal of Environmental Impact Assessment
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• v.10 no.1
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• pp.9-19
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• 2001

An intensive watershed survey including water quality measurement of 6 times was carried out in order to find out the relationship between pollutant load and water quality in a small stream watershed where livestock wastewater is the main source of water pollution. The findings from the survey are as follows. 1) The number of livestock showed large disagreement among county office, myon, and insite survey. It is vital to check the data at the beginning of watershed survey. 2) The fluctuation of streamflow and water quality was so large depending on the day of measurement that it is essential to set up continuous telemetering system to get reliable data about delivery ratio of pollutants. 3) It was helpful for setting the priority of investigation to check water quality and quantity at several points along the stream after dividing the watershed into 5 drainage areas. 4) To control the livestock wastewater, especially in case of cows, it is necessary to have roof system and prevent overland flow from the ground. In case of pig farms, it is recommended to have public treatment system instead of private treatment system. The exact emission load of livestock wastewater was difficult to estimate, and requires more study.

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.5
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• pp.35-42
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• 1995

his paper is to develop a GIS application model (GISCELWAB) for the spatial simulation of surface runoff from a small watershed. The model was constituted by three submodels : The input data extraction model (GISINDATA) which prepares cell-based input data automatically for a given watershed, the cell water balance model (CELWAB) which calculates the water balance for a cell and simulates surface runoff of watershed simultaneously by the interaction of cells, and the output data management model (GISOUTDISP) which visualize the results of temporal and spatial variation of surface runoff. The input data extraction model was developed to solve the time-consuming problems for the input-data preparation of distributed hydrologic model. The input data for CELWAB can be obtained by extracting ASCII data from a vector map. The output data management model was developed to convert the storage depth and discharge of cells into grid map. This model enables to visualize the spatial formulation process of watershed storage depth and surface runoff wholly with time increment.

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.3_4
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• pp.23-33
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• 1995

Geographic data which are difficult to handle by the characteristics of spatial variation and variety turned into a possibility to analyze with tlie computer-aided digital map and the use of Geographic Information System(GIS). The purpose of this study is to develop and apply a GIS application model (GISCELWAB) for the spatial simulation of surface runoff from a small watershed. This paper discribes the modeling procedure and the applicability of the cell water balance model (CELWAB) which calculates the water balance of a cell and simulates surface runoff of watershed simultaneously by the interaction of cells. The cell water balance model was developed to simulate the temporal and spatial storage depth and surface runoff of a watershed. The CELWAB model was constituted by Inflow-Outflow Calculator (JOC) which was developed to connect cell-to-cell transport mechanism automatically in this study. The CELWAB model requests detail data for each component of a cell hydrologic process. In this study, therefore, BANWOL watershed which have available field data was selected, and sensitivity for several model parameters was analyzed. The simulated results of surface runoff agreed well with the observed data for the rising phase of hydrograph except the recession phase. Each mean of relative errors for peak discharge and peak time was 0.21% and2.1 1% respectively. In sensitivity analysis of CELWAB , antecedent soil moisture condition(AMC) affected most largely the model.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.1
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• pp.87-97
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• 2004

The paper presents the results from the applications of the Water Erosion Prediction Project (WEPP) model to a single plot, and also a small watershed in the Mid Korean Peninsula which is comprised of hillslopes and channels along the water courses. Field monitoring was carried out to obtain total runoff, peak runoff and sediment yield data from research sites. For the plot of 0.63 ha in size, cultivated with com, the relative error of the simulated total runoff, peak runoff rates, and sediment yields using WEPP ranged from -16.6 to 22％, from -15.6 to 6.0％, and from 23.9 to 356.4％ compared to the observed data, respectively. The relative errors for the upland watershed of 5.1 ha ranged from -0.7 to 11.1 ％ for the total runoff, from -6.6 to 35.0 ％ for the sediment yields. The simulation results seem to justify that WEPP is applicable to the Korean dry croplands if the parameters are correctly defined. The results from WEPP applications showed that the major source areas contributing sediment yield most are downstream parts of the watershed where runoff concentrated. It was suggested that cultural practice be managed in such a way that the soil surface could be fully covered by crop during rainy season to minimize sediment yield. And also, best management practices were recommended based on WEPP simulations.