• 한국방재학회 논문집
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• 제9권6호
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• pp.125-131
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• 2009

본 연구의 목적은 Bhaskar 등(2000)의 연구를 우리나라 유역에 적용하여, 홍수사상에 따른 유출수문곡선의 특성을 이용한 돌발홍수지수를 산정함으로써 돌발홍수의 심각성 정도를 정량화하고자 하였다. 또한, Bhaskar 등(2000)의 연구내용을 보다 확장하여 돌발홍수지수와 강우강도, 강우지속시간 및 총유출량과의 상관관계를 정량적으로 분석하였다. 본 연구에서는 미계측유역인 매곡천 유역의 과거 31개의 호우사상에 대한 돌발홍수의 상대심도를 파악하기 위해, 강우-유출모의를 통한 홍수수문곡선을 모의하고 이에 따른 돌발홍수지수를 산정하여 돌발홍수심도를 정량화하였다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2007년도 학술발표회 논문집
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• pp.1454-1458
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• 2007

The determination of feasible design flood is the most important to control flood damage in river management. Model parameters should be calibrated using observed discharge but due to deficiency of observed data the parameters have been adopted by engineer's empirical sense. Storage constant in the Clark unit hydrograph method mainly affects magnitude of peak flood. This study is to estimate the storage constant based on the observed rainfall-runoff data at the three stage stations in the Imjin river basin and the three stage stations in the Ansung river basin. In this study four methods have been proposed to estimate the storage constant from observed rainfall-runoff data. The HEC-HMS model has been adopted to execute the sensitivity of storage constant. A criteria has been proposed to determine storage constant based on the results of the observed hydrograph and the HEC-HMS model.

• 한국관개배수논문집
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• 제5권1호
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• pp.8-19
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• 1998

The existing flood runoff models, Complex Hydrograph and HEC-1, have some problems which do not properly represent runoff characteristics on the Korean paddy basin and their basin slopes. In this study, FAS(Flood ,Analysis System) was developed in order t

• 한국농공학회지
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• 제32권3호
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• pp.87-101
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• 1990

The purpose of this study is to estimate the flood discharge and runoff volume at a stream by using geomorphologic parameters obtained from the topographic maps following the law of stream classification and ordering by Horton and Strahier. The present model is modified from Cheng' s model which derives the geomorphologic instantaneous unit hydrograph. The present model uses the results of Laplace transformation and convolution intergral of probability density function of the travel time at each state. The stream flow velocity parameters are determined as a function of the rainfall intensity, and the effective rainfall is calculated by the SCS method. The total direct runoff volume until the time to peak is estimated by assuming a triangular hydrograph. The model is used to estimate the time to peak, the flood discharge, and the direct runoff at Andong, Imha. Geomchon, and Sunsan basin in the Nakdong River system. The results of the model application are as follows : 1.For each basin, as the rainfall intensity doubles form 1 mm/h to 2 mm/h with the same rainfall duration of 1 hour, the hydrographs show that the runoff volume doubles while the duration of the base flow and the time to peak are the same. This aggrees with the theory of the unit hydrograph. 2.Comparisions of the model predicted and observed values show that small relative errors of 0.44-7.4% of the flood discharge, and 1 hour difference in time to peak except the Geomchon basin which shows 10.32% and 2 hours respectively. 3.When the rainfall intensity is small, the error of flood discharge estimated by using this model is relatively large. The reason of this might be because of introducing the flood velocity concept in the stream flow velocity. 4.Total direct runoff volume until the time to peak estimated by using this model has small relative error comparing with the observed data. 5.The sensitivity analysis of velocity parameters to flood discharge shows that the flood discharge is sensitive to the velocity coefficient while it is insensitive to the ratio of arrival time of moving portion to that of storage portion of a stream and to the ratio of arrival time of stream to that of overland flow.

• 한국물환경학회지
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• 제21권6호
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• pp.682-686
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• 2005

Recently some urban areas have been flooded due to heavy storm rainfalls. Though major causes of these floodings may be attributed to localized heavy rainfalls, other factors are related to urban flooding including deficiency of storm sewer network capacity, change of surface runoff due to covered open channels, and operational problems of storm drainage pump stations. In this study, hydrologic and hydraulic analysis of Sutak basin in Guri city were carried out to evaluate flooding problems occurred during the heavy storm in July, 2001. ArcView, a world most widely used GIS tool, was used to extract required data for the hydrologic analysis including basin characteristics data, concentration times, channel routing data, land use data, soil distribution data and SCS runoff curve number generation from digital maps. HEC-HMS, a GIS-based runoff simulation model, was successfully used to simulate the flood inflow hydrograph to Sutak pumping station.

• 물과 미래
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• 제25권1호
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• pp.93-100
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• 1992

Abstract A study on the Derivation of the Unit Hydrograph using Multiple Regression Moe이. The purpose of this study is to deriver an optimal unit hydrograph suing the multiple regression model, particularly when only small amount of data is available. The presence of multicollinearity among the input data can cause serious oscillations in the derivation of the unit hydrograph. In this case, the oscillations in the unit hydrograph ordinate are eliminated by combining the data. The data used in this study are based upon the collection and arrangement of rainfall-runoff data(1977-1989) at the Soyang-river Dam site. When the matrix X is the rainfall series, the condition number and the reciprocal of the minimum eigenvalue of XTX are calculated by the Jacobi an method, and are compared with the oscillation in the unit hydrograph. The optimal unit hydrograph is derived by combining the numerous rainfall-runoff data. The conclusions are as follows; 1)The oscillations in the derived unit hydrograph are reduced by combining the data from each flood event. 2) The reciprocals of the minimum eigen\value of XTX, 1/k and the condition number CN are increased when the oscillations are active in the derived unit hydrograph. 3)The parameter estimates are validated by extending the model to the Soyang river Dam site with elimination of the autocorrelation in the disturbances. Finally, this paper illustrates the application of the multiple regression model to drive an optimal unit hydrograph dealing with the multicollinearity and the autocorrelation which cause some problems.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1998년도 학술발표회 발표논문집
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• pp.34-40
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• 1998

The existing flood runoff models, Complex Hydrograph and HEC-1, have some problems which do not properly represent runoff characteristics on the Korean paddy basin and their basin slopes. In this study, FAS(Flood Analysis System) was developed in order to supplement those problems, which was built calibrating runoff curve number for paddy basin and applying basin slopes to classify 5 levels. And also the FAS can synthesize the flood hydrographs of subbasin and analyze flood routing along a stream. To verify the applicability of the FAS, the computed flood hydrographs were compared with the observed hydrographs from the four watersheds. In the small basin smaller than 10$\textrm{km}^2$, the results of the FAS did not completely agree with the observed ones due to concentration time delay of paddy storage effect while in the medium and large size basin showed good agreements between the observed and computed ones. Therefore, it was concluded that the FAS could be applied for the flood analysis of Korean watershed which was characterized by paddy storage effect.

• 한국농공학회논문집
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• 제54권3호
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• pp.65-74
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• 2012

In this study, three different unit hydrograph methods (NRCS, Snyder and Clark) in the HEC-HMS were compared to find better fit with the observed data in the Namgang-Dam watershed. The Sancheong, Shinan, and Changchon in Namgang-Dam watershed were selected as the study watersheds. The input data for HEC-HMS were calculated land use, digital elevation map, stream, and watershed map provided by WAter Management Information System (WAMIS). Sixty six storms from 2004 to 2011 were selected for model calibration and validation. Three unit hydrograph methods were compared with the observed data in terms of simulated runoff volume, and peak runoff for the selected storms. The results showed that the coefficient of determination ($R^2$) for the peak runoff was 0.8295~0.9999 and root mean square error (RMSE) was 0.029~0.086 mm/day for calibration stages. In the model validation, $R^2$ for the peak runoff was 0.9061~0.9916 and RMSE was 0.030~0.088 mm/day which were more accurate than calibrated data. Analysis of variance showed that there was no significant difference among the three unit hydrograph methods.

• 한국환경과학회지
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• 제2권3호
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• pp.193-199
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• 1993

This study has two objectives. One is developing the runoff model for Hoe-Dong Reservoir basin located at the upstream of Su-Young River in Pusan. To develop the runoff model, basic hydrological parameters - curve number to find effective rainfall, and storage coefficient, etc. - should be estimated. In this study, the effective rainfall was calculated by the SCS method, and the storage coefficient used in the Clark watershed routing was cited from the report of P.E.B. The other is the derivation of transfer function for Hoe-Dong Reservoir basin. The linear, discrete, input-output model which contained six parameters was selected, and the parameters were estimated by the least square method and the correlation function method, respectively. Throughout this study, rainfall and flood discharge data were based on the field observation in 1981.8.22 - 8.23 (typhoon Gladys). It was observed that the Clark watershed routing regenerated the flood hydrograph of typhoon Gladys very well, and this fact showed that the estimated hydrological parameters were relatively correct. Also, the calculated hydrograph by the linear, discrete, input-output model showed good agreement with the regenerated hydrograph at Hoe-Dong Dam site, so this model can be applicable to other small urban areas. Key Words : runoff, effective rainfall, SCS method, clark watershed iou상ng, hydrological parameters, parameter estimation, least square method, correlation function method, input-output model, typhoon gladys.

• 한국농공학회지
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• 제37권3_4호
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• pp.34-47
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• 1995

It is experienced fact as a regular annual event that the structure to he designed on unreasonable flood for the agricultural structures including reservoirs have been brought not only loss of lives, but also enormous property damage. For the solution of this problem at issue, this study was conducted to develop an optimal runoff hydrograph model by comparison of the peak flows and time to peak between observed and simulated flows derived by linear time-invariant and linear time-variant models under the condition of having a short duration of heavy rainfall with uniform rainfall intensity at nine small watersheds which are within the range of 55.9 to 140.7 square kilometers in area in Han, Geum, Nagdong and Yeongsan Rivers. The results obtained through this study can be summarized as follows. 1. Storage constants and Gamma function arguments were calculated within the range of 1.2 to 6.42 and of 1.28 to 8.05 respectively by the moment method as the parameters for the analysis of runoff hydrograph based on linear time-invariant model. 2. Parameters for both linear time-invariant and linear time-variant models were calibrated with nine gaged watershed data, using a trial and error method. The resulting parameters including Gamma function argument, N and storage constant, K for linear time-invariant model were related statistically to watershed characteristic variables such as area, slope, length of main stream and the centroid length of the basin. 3. Average relative errors of the simulated peak discharge of calibrated runoff hydrographs by using linear time-variant and linear time-invariant models were shown to be 0.75 and 5.42 percent respectively to the peak of observed runoff hydrographs. Correlation coefficients for the statistical analysis in the same condition were shown to be 0.999 and 0.978 with a high significance respectively. Therefore, it can be concluded that the accuracy of a linear time-variant model is approaching more closely to the observed runoff hydrograph than that of a linear time-invariant model in the applied watersheds. 4. Average relative errors of the time to peak of calibrated runoff hydrographs by using linear time-variant and linear time-invariant models were shown to be 16.44 and 19.89 percent respectively to the time to peak of observed runoff hydrographs. Correlation coefficients in the same condition were also shown to be 0.999 and 0.886 with a high significance respectively. 5. It can be seen that the shape of simulated hydrograph based on a linear time- variant model is getting closer to the observed runoff hydrograph than that of a linear time-invariant model in the applied watersheds. 6. Two different models were verified with different rainfall-runoff events from data for the calibration by relative error and correlation analysis. Consequently, it can be generally concluded that verification results for the peak discharge and time to peak of simulated runoff hydrographs were in good agreement with those of calibrated runoff hydrographs.