• Korean Journal of Agricultural Science
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• v.2 no.1
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• pp.281-300
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• 1975

The precipitation data and water level data in twenty-four sampling places, to investigate same hydrological quantities along the basin of Geum River, have been analyzed, and the findings for the first report are summarized as follows. 1. The mean annual precipitation in the basin of Geum River is of 1203mm, and the areal weight of areal rainfall by Thiessen's method shows as Table 1. 2. The areas where have maximum annual precipitation of 1501 to 2000mm, are seventeen placed among twentyfour gauging stations, and it is founded to be the highest rate with 71 percents. The precipitation of below 1500mm is measured in the other three statinons, and that of above 2001mm in four stations, too. 3. The areas where have maximum rainfall of 201 to 300mm within a day, are fifteen places, and that comes in the highest rate of distribution with 63 percents. 4. As to distribution of the places with maximum rainfall of below and above 300mm within two days, it shows respectively 50 percents. 5. The areas where have maximum rainfall of 301 to 400mm within three days, are fifteen places, and it is the highest rate of distribution with 63 percents. 6. The fourteen places have maximum rainfall of 401 to 600mm within a continuous day, it is the highest rate of distribution with 58 percents. 7. Table 5 shows probable maximum rainfall within a day, and it does the most rainfall a long the upper stream of Daecheong dam site around Muju, and the next shows in the areas around Ganggyeung, Gongju and Buyeu. 8. During irrigation period on paddy corp, for 100 days from early ten days in June to early ten days in September the areas where have rainfall of 601 to 800mm are sixteen places, and it is the highest rate of distribution with 76 percents, as Table 6 9. The areas where have effective rainfall of 501 to 600mm, are fifteen places, and it is the highest rate of distribution with 71 percents. Thirteen places have the effective ratio of 66 to 75 percents, and it means 62 percents of distribution, and the next, 76 to 85 percents in the seven places, and it comes 33 percents. 10. The areas where have probable effective rainfall of 401 to 500mm, are fourteen places, which is about 100mm less than mean effective rainfall in each area, and that comes 67 percents of distribution. 11. A particular year can not be appointed as once -in-10 year drought in the same year as a whole in the basin of Geum River. 12. The basin of Geum River, s/S being 0.53 to 0.74, has relatively proper conditions in the aspect of water resources.

• Journal of Environmental Science International
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• v.26 no.12
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• pp.1389-1397
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• 2017

In this study, we calculated the fixed-type Areal Reduction Factor (ARF) of the Hancheon River basin in Jeju Island, and compared the calculated ARF and the ARF of the four major river basins suggested by the Ministry of Land, Infrastructure and Transport. As a result, the maximum fluctuation ratios of ARF for the four major river basins calculated using area, frequency, and initial duration time were significant: 7.61% for the Hangang River basin; 12.69% for the Nakdonggang River basin; 8.09% for the Kumgang River basin; and 17.98% for the Yeongsangang River basin. In addition, the differences between the maximum and minimum value of ARF for the Hancheon River basin based on 48 hours was 2.13%, and it was smaller than the one for the four major river basins: 8.92% for the Hangang River basin; 11.41% for the Nakdonggang River basin; 8.87% for the Kumgang River basin; and 17.17% for the Yeongsangang River basin. The Yeongsangang River basin had the highest difference.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.1
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• pp.9-15
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• 2013

This study is to evaluate the parameter behavior of VfloTM distributed rainfall-runoff model by applying 3 kinds of rainfall interpolation methods viz. Inverse Distance Weighting (IDW), Kriging (KRI), and Thiessen network (THI). For the 1,544 $km^2$ Dongcheon watershed of Nakdong river, the model was calibrated using 4 storm events in 2007 and 2009, and validated using 2 storm events in 2010. The model was calibrated with Nash-Sutcliffe model efficiency of 0.97 for IDW, 0.94 for KRI, and 0.95 for THI respectively. For the sensitive parameters, the saturated hydraulic conductivity ($K_{sat}$) for IDW, KRI, and THI were 0.33, 0.31, and 0.43 cm/hr, and the soil suction head at the wetting front (${\Psi}_f$) were 4.10, 3.96, and 5.19 cm $H_2O$ respectively. These parameters affected the infiltration process by the spatial distribution of antecedent moisture condition before a storm.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.93-98
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• 2001

This study was performed to analyse the rainfall and the rainfall-runoff characteristics of a rural watershed. The Sangwha basin($105.9km^{2}$) in the Geum river system was selected for this study. The arithmetic mean method, the Thiessen's weighing method, and the isohyetal method were used to analyse areal rainfall distribution and the Huff's quartile method was used to analyse temporal rainfall distribution. In addition, daily runoff analyses were peformed using the DAWAST and tank model. In the model calibration, the data from June through November, 1999 were used. In the model calibration, the observed runoff depth was 513.7mm and runoff rate was 45.2%, and the DAWAST model simulated runoff depth was 608.6mm and runoff rate was 53.5%, and the tank model runoff depth was 596.5mm and runoff rate was 52.5%, respectively. In the model test, the data from June through November, 2000 were used. In the model test, the observed runoff depth was 1032.3mm and runoff rate was 72.5%, and the DAWAST model simulated runoff depth was 871.6mm and runoff rate was 61.3%, and the tank model runoff depth was 825.4mm and runoff rate was 58%, respectively. The DAWAST and tank model's $R^{2}$ and RMSE were 0.85, 3.61mm, and 0.85, 2.77mm in 1999, and 0.83, 5.73mm, and 0.87, 5.39mm in 2000, respectively. Both models predicted low flow runoff better than flood runoff.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.2
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• pp.493-503
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• 2014

The NRCS-CN method is generally applied for estimating effective rainfalls in practice, in which the basin-averaged CN is normally used. In order to develop a more appropriate method for estimating effective rainfalls in a basin, this study compared estimated effective rainfalls from two distinct methods with the observed direct runoff. The first method is to estimate the basin-representative effective rainfall using the basin-averaged CN (hereafter, effective rainfall I), whereas the second method to estimate the basin-averaged effective rainfall through areal-averaging sub-area effective rainfalls corresponding to the soil type and landuse type (hereafter, effective rainfall II). The overall results indicated that the effective rainfall II was higher than the effective rainfall I and closer to the observed direct runoff. The study also performed error analyses to verify that the effective rainfall II can be applied in practice in a basin as more accurate estimate of basin-representative effective rainfall.

• Journal of Korea Water Resources Association
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• v.37 no.3
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• pp.233-240
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• 2004

Most of hydrological analyses in the field of water resources are launched by gathering and analyzing rainfall data. Several methods have been developed to estimate areal rainfall from point rainfall data and to fill missing or ungaged data. Thiessen and Reciprocal Distance Squared(RDS) methods whose parameters are only dependent on inter-station distance are classical work in hydrology, but these techniques do not provide a continuous representation of the hydrologic process involved. In this study, kriging technique was applied to rainfall analysis in Nakdong river basin in order to complement the defects of these classical methods and to reflect spatial characteristics of regional rainfall. After spatial correlation and semi-variogram analyses were performed to perceive regional rainfall property, kriging analysis was performed to interpolate rainfall data for each grid Thus, these procedures were enable to estimate average rainfall of subbasins. In addition, poor region of rainfall observation was analyzed by spatial interpolation error for each grid and mean error for each subbasin.

• Journal of Korea Water Resources Association
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• v.39 no.4 s.165
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• pp.335-346
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• 2006

Among various input data to hydrologic models, rainfall measurements arguably have the most critical influence on the performance of hydrologic model. Traditionally, hydrologic models have relied on point gauge measurements to provide the area-averaged rainfall information. However, rainfall estimates from gauges become inadequate due to their poor representation of areal rainfall, especially in situations with sparse gauge network. Alternatively, radar that covers much larger areas has become an attractive instrument for providing area- averaged precipitation information. Despite of the limitation of the QPE(Quantitative Precipitation Estimation) using radar, we can get the better information of spatial variability of rainfall fields. Also, rain-gauges give us the better quantitative information of rainfall field. Therefore, in this study, we developed improved methodologies tu estimate rainfall fields using an ordinary cokriging technique which optimally merges radar reflectivity data into rain-gauges data.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.3B
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• pp.269-279
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• 2009

The design flood estimation in a large river basin has a lot of uncertainties in areal reduction factors, time-spatial rainfall distribution, and parameters of rainfall-runoff model. The use of historical concurrent rainfall events for estimating design flood would reduce the uncertainties. This study presents a procedure for estimating design floods using historical rainfall events and storage function model. The design rainfall and time-spatial distribution were determined through analyzing concurrent rainfall events, and the design floods were estimated using storage function model with a non-linear hydrology response. To evaluate the applicability of the procedure of this study, the estimated floods were compared to results of frequency analysis of flood data. Both floods gave very similar results. It shows the applicability of the procedure presented in this study for estimating design floods in practices.

• Current Research on Agriculture and Life Sciences
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• v.15
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• pp.53-67
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• 1997

The objective of this study is to provide with the hydro-meteological and probabilistic characteristics of the storms of typhoons that have been passed through the Korean peninsula during the last twenty-three years since 1961. The paths and intensities of the typhoons were analyzed. Fifty weather stations were selected and the rainfall data during typhoon periods were collected. Rainfall data were analyzed for the patterns and probabilistic distributions. The results were presented to describe the areal distributions of probabilistic characteristics. The results obtained from this study can be summarized as follows: 1. The most frequent typhoon path that has passed through the Korean peninsula was type E, followed by types CWE, W, WE, and S. The most frequent typhoon intensity was type B, followed by A, super A, and e types, respectively. 2. The third quartile typhoon rainfall patterns appear most frequently followed by the second, first, and last quartiles, respectively, in Seoul, Pusan, Taegu, Kwangju and Taejon. The single typhoon rainfalls with long rainfall durations tended to show delayed type rainfall patterns predominantly compared to the single rainfalls with short rainfall durations. 3. The most frequent probabilistic distribution of typhoon rainfall event is Pearson type-III, followed by Two-parameter lognormal distribution, and Type-I extremal distribution. 4. The most frequent probability distribution model of seashore location was Pearson type-III distribution. The most frequent probability distribution model of inland location was two parameter lognormal distribution.

• KCID journal
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• v.1 no.2
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• pp.36-47
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• 1994

미국 펜실베이니아 주의 4개 지역에 대해 면적우량을 분석하였다. 강수량이 제일 큰 지점에서 시작하여 이 지점 주위로 직사각형의 블럭을 확장하여 만들었다. 이 직사각형 블럭의 강수량을 구한 후 최대 지점 강수량에 대한 비를 구하였다. 이 강수량 비(Relative storm magnitudes)를 플롯트하여 기존의 커브와 비교하였으며, 각 지역에 대해 여름과 겨울의 강수량비를 각각 구하였다. 또한 등우량선도를 이용한 분석도 시도해 보았다. 이 연구에서 구