• Journal of Korean Society of Forest Science
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• v.99 no.4
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• pp.559-567
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• 2010

This study was conducted to investigate the hydrological characteristics of groundwater level change and rainfall hydrological runoff processes caused by tunnel construction at Milbot bog located in Mt. Cheonseong. Data were collected from July 2004 to May 2008. The results were summarized as follows: The occurrence time of the direct runoff caused by unit rainfall at the Milbot bog were tended to be slower than those at general mountainous basin. Also, runoff did not sensitively respond to amount of rainfall at the most of the long and short term hydrograph. The annual runoff rates from 2004 to 2008 were 0.26, 0.13, 0.16, 0.25 and 0.27, respectively, slightly increased after 2005 regardless of the tunnel construction. Thus, the function of Milbot bog will be weakened, and it supposed to be changed to land in the future because of increasing annual runoff. The annual runoff rate for 4 years was 0.19, which is greatly lower than that of general mountainous basin. The recession coefficient of the direct runoff in short term hydrograph was ranged to 0.89~0.97, which is much larger than that of the general mountainous basin, 0.2~0.8. The recession coefficient of base flow ranged from 0.93 to 0.99, which are similar to general mountainous watershed's values. Groundwater level of Milbot bog increased or decreased in proportion to rainfall intensity, and in the descending time after the groundwater level was reached at peak point, it tends to be decreased very slowly. Also, groundwater level increased or decreased maintaining relatively high value after precedent rainfall. Groundwater level was highest during summer with heavy rainfall, but was lowest during winter. Average groundwater levels decreased annually from 2004 to 2008, -8.48 cm, -14.60 cm, -20.46 cm, -20.11 cm, -28.59 cm, respectively. Therefore, it seems that the Milbot bog is becoming dry and losing its function as a bog.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.245-248
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• 2002

The Soil Conservation Service (SCS) developed a unique procedure for estimating direct runoff from storm rainfall. But, It is very difficult to estimate accurately flood hydrograph by SCS method, because the initial ion of Ia(0.2Sa) itself has lots of systematic errors and there is no investigation on Ia in the Korean watershed. The maximum storage capacity of Umax is calibrated in the DAWAST model and is related to the present ability of rainfall to be infiltrated into the unsaturated soil. Effective rainfall for design and real-time flood hydrograph can be estimate more reasonably by introducing new Ia relationship made from the rainfall-runoff data observed in the Korean watersheds.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.3
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• pp.52-63
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• 1997

A CELTHYM(CEll-based Long-Term HYdrologic Model), a pre-processor and a post processor that can be integrated with geographic information system ( GIS) were developed to predict the stream flow of the small watershed. The CELTHYM was calibrated and verified with measured runoff data at the WS # 1 and WS # 3 that are testing water sheds of Seoul Nat' 1 Univ., dept. of agricultural engineering, in Ansan city, Kyunggi province, South Korea. The results of tests are in good agreement with measured data and usable for other application, but the component of direct runoff and water balance on paddy fields need more study.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.783-786
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• 2008

The main goal of this study is to understand the effects of direct-runoff of chemistry and organic fertilizers which are adsorbing to sediment from farmland and non-point source discharge characteristics which are discharged to stream with soil erosion when rainfalls. pollutographs of TSS, BOD, COD, TN, and TP were measured for 10 rainfall events at watershed. EMC (Event Mean Concentration) were calculated for each rainfall event using quality and quantity measured. The result shows that the EMC ranges of 95% confidence intervals are 50.5-203 mg/L for TSS, 0.8-14.2 mg/L for $BOD_5$, 4.2-20.7 mg/L for $COD_{Mn}$, 0.2-0.5 mg/L for TP, 2.4-4.5 mg/L for TN, 1.36-3.04 mg/L for NO3--N, 0.13-0.42 mg/L for NH4+-N and 0.82-1.77 mg/L for TKN.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.4
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• pp.75-83
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• 2016

Streamflow is composed of baseflow and direct runoff. However, most of streamflow during dry seasons depends on baseflow. Thus, baseflow analysis is very important to simulate streamflow of dry seasons. Generally, baseflow analysis is conducted using watershed-scale runoff models due to diffilculty of measuring baseflow. However, it is needed to understand and review how the model simulates baseflow because each model uses inherent baseflow analysis techniques. In this study, SWAT, HSPF, PRMS-IV were reviewed focusing on baseflow and soil water. HSPF and PRMS-IV calculate baseflow using the variables which depends on user, so the baseflow analysis results of HSPF and PRMS-IV are not consistent. Moreover, soil structures which were assumed from HSPF and PRMS-IV, since these two models assume soil structure as two soil zones and three conceptual reservoirs, were not enough to describe real soil structure. On the other hand, baseflow in SWAT is calculated using baseflow recession constant which can consider the characteristics of aquifer and also, soil structure in SWAT is similar to real soil structures. Thus, baseflow analysis result from SWAT was concluded as the most suitable and reliable model because SWAT can reflect the characteristics and soil structure which is close to reality.

• Journal of the Korean Geographical Society
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• v.39 no.1
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• pp.45-55
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• 2004

The paper describes the rainfall-runoff. soil moisture distribution and subsurface flow of 'U-shaped Goll' valley head slope to evaluate quantitatively the interaction between the water circulation system and geomorphic development. The findings are as follows: The fissure and the pipe entrance in front of 'U-shaped Goll' introduce a lot of direct runoff into either the soil pipe or the soil layer to accelerate the erosion of the soil layer, so that they are likely to contribute to the expansion and development of the soil pipe. Most of soil water is to be drained in pipe flow, while some of remaining soil water is to be fed into groundwater. Therefore, low rainfall intensity is thought to let both the groundwater level and the pipe flow react sensitively by the effects of the precedent rainfall even at events: As a result, the soil pipe is said to be an important factor having influence upon the material balance of 'U-shaped Goll' valley head slope. On the other hand, the groundwater shows greater specific flux at the top than at the bottom, and relatively larger specific flux is applied to the top to make 'U-shaped Goll' valley head slope go back to the top.

• Water for future
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• v.20 no.4
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• pp.267-278
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• 1987

This study aims at the decision of geomorphologic instantaneous unit hydrograph(GIUH) model parameter fore the ungaged or the data deficiented Basin, to analyze rainfall runoff relation in river basin by applying queueing theory with geomorphologic factors.The concept of GIUH model is based upon the principle of queueing theory of rain drops which may follow many possible routes during rainfall period within watershed system to ist outlet. Overland flow and stream flow can be simulated, respectively, by linear reservoir and linear channel conceptual models. Basically, the model is a mon-lineal and time variant hydrologic system model. The techniques of applying are adopted subarea method and mean-value method, the watershed is divided according to its stream number and order. To prove it to be applicable, the GIUH model is applied to the Wi-Stream basin of Nak-Dong River(Basin area; 475.53$\textrm{km}^2$), southen part of Korea. The simulated and the observed direct runoff hydrographs are compared with the peak discharge, times to peak and coefficients of efficiency, respectively, and the results show quite satisfactory.Therefore, th GIUH model can be extensively applied for the runoff analysis in the ungaged and the data deficiented basin.

• Journal of Korea Water Resources Association
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• v.36 no.2
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• pp.183-193
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• 2003

A relation between the temporal variation of rainfall and direct runoff was characterized using temporal indexes of rainfall(1st, 2nd, 3rd, and 4th moment). Curve Number has a relation with 1st and 2nd moment for AMCIII condition when the rainfall duration is relative (10th quantile). Also peak runoff ratio(QP/Q) has a relation with 1st and End moment for AMCIII condition as well as 3rd and 4th moment for AMC I condition. Considering all durations of rainfall, alternatively, Curve Number has a relation with 1st and 2nd moment for AMCIIIcondition besides every moments for AMC I condition. But peak runoff ratio(QP/Q) has few relations excepting 3rd and 4th moment for AMC I condition. As a results, temporal indexes of rainfall are useful to determine curve numbers regarding the temporal variation of rainfall.

• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.4
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• pp.55-64
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• 2021

The expansion of upland crop cultivation in rice paddy fields is recommended by the Korean government to solve the problem of falling rice price and reduction of rice farmer's income due to oversupply of rice. However, water use efficiency is significantly influenced by the land use change from paddy field to upland. Therefore, this study aimed to evaluate the water budget of soybean grown in using APEX (Agricultural Policy and Environmental eXtender) model. The amount of runoff was measured in a test bed located in Iksan, Jeollabu-do and used to calibrate and validate the simulated runoff by APEX model. From 2019 to 2020, the water budget of soybean grown in uplands were estimated and compared with the one grown in paddy fields. The calibration result of AP EX model for runoff showed that R² (Coefficient of determination) and NSE (Nash-Sutcliffe efficiency) were 0.90 and 0.89, respectively. In addition, the validated results of R² and NSE were 0.81 and 0.62, respectively. The comparative study of each component in water budget showed that the amounts of evapotranspiration and percolation estimated by APEX model were 549.1 mm and 375.8mm, respectively. The direct runoff amount from upland was 390.1 mm, which was less than that from paddy fields. The average amount of irrigation water was 28.7 mm, which was very small compared to the one from paddy fields.

• Spatial Information Research
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• v.20 no.5
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• pp.25-35
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• 2012

This study compared the influence of water quality according to the data sources of spatial information. Firstly, land cover map was constructed through image classification of Daecheong-dam basin and the accuracy of image classification from satellite image showed high as 88.76% in comparison with the large-scaled land cover map in Ministry of Environment, to calculate Event Mean Concentration (EMC) by land cover that impact on the evaluation of nonpoint source pollutant loads. Also curve number and direct runoff were calculated by spatial overlay with soil map and land cover map from image classification. And Seokcheon and Daecheong-Dam basin showed high in the analysis of curve number and direct runoff. Samgacheon-Joint and Sokcheon-Downstream basin showed high in the nonpoint source pollutant loads of BOD from direct runoff and EMC. And Samgacheon-Joint and Bonghwangcheon- Downstream basin showed high in the nonpoint source pollutant loads of TN and TP. Nonpoint source pollutant loads from image classification were compared with those by the land cover map from Ministry of Environment to present the effectivity of nonpoint source pollutant loads from satellite image. And Daecheong-Dam Upstream basin showed high as 10.64%, 11.70% and 20.00% respectively in the errors of nonpoint source pollutant loads of BOD, TN, and TP. Therefore, it is desirable that spatial information including with paddy and dry field is applied to the evaluation of nonpoint source pollutant loads in order to simulate water quality of basin effectively.