• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2255-2265
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• 2013

This study presents the width function-based Clark model. To this end, rescaled width function with distinction between hillslope and channel velocity is used as time-area curve and then it is routed through linear storage within the framework of not finite difference scheme used in original Clark model but analytical expression of linear storage routing. There are three parameters focused in this study: storage coefficient, hillslope velocity and channel velocity. SCE-UA, one of the popular global optimization methods, is applied to estimate them. The shapes of resulting IUHs from this study are evaluated in terms of the three statistical moments of hydrologic response functions: mean, variance and the third moment about the center of IUH. The correlation coefficients to the three statistical moments simulated in this study against these of observed hydrographs were estimated at 0.995 for the mean, 0.993 for the variance and 0.983 for the third moment about the center of IUH. The shape of resulting IUHs from this study give rise to satisfactory simulation results in terms of the mean and variance. But the third moment about the center of IUH tend to be overestimated. Clark model proposed in this study is superior to the one only taking into account mean and variance of IUH with respect to skewness, peak discharge and peak time of runoff hydrograph. From this result it is confirmed that the method suggested in this study is useful tool to reflect the heterogeneity of drainage path and hydrodynamic parameters. The variation of statistical moments of IUH are mainly influenced by storage coefficient and in turn the effect of channel velocity is greater than the one of hillslope velocity. Therefore storage coefficient and channel velocity are the crucial factors in shaping the form of IUH and should be considered carefully to apply Clark model proposed in this study.

• Journal of Korea Water Resources Association
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• v.51 no.1
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• pp.19-33
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• 2018

This study proposed a rainfall-runoff model for the purpose of real-time flood warning in urban basins. The proposed model was based on the shot noise process, which is expressed as a sum of shot noises determined independently with the peak value, decay parameter and time delay of each sub-basin. The proposed model was different from other rainfall-runoff models from the point that the runoff from each sub-basin reaches the basin outlet independently. The model parameters can be easily determined by the empirical formulas for the concentration time and storage coefficient of a basin and those of the pipe flow. The proposed model was applied to the total of three rainfall events observed at the Jungdong, Guro 1 and Daerim 2 pumping stations to evaluate its applicability. Summarizing the results is as follows. (1) The unit response function of the proposed model, different from other rainfall-runoff models, has the same shape regardless of the rainfall duration. (2) The proposed model shows a convergent shape as the calculation time interval becomes smaller. As the proposed model was proposed to be applied to urban basins, one-minute of calculation time interval would be most appropriate. (3) Application of the one-minute unit response function to the observed rainfall events showed that the simulated runoff hydrographs were very similar to those observed. This result indicates that the proposed model has a good application potential for the rainfall-runoff analysis in urban basins.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.17-24
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• 2018

The HEC-HMS model was applied to identify the rainfall-runoff processes for the Anseongchun basin, where the lower part of the stream has been damaged severely by tropical storms in the past. Modeling processes include incorporating with the SCS-CN model for loss, Clark's UH model for transformation, exponential recession model for baseflow, and Muskingum model for channel routing. The parameters were calibrated through an optimization technique using a trial and error method. Sensitivity analysis after calibration was performed to understand the effects of parameters, such as the time of concentration, storage coefficient, and base flow related constants. Two storm water events were simulated by the model and compared with the corresponding observations. Good accuracy in predicting the runoff volume, peak flow, and the time to peak flow was achieved using the selected methods. The results of this study can be used as a useful tool for decision makers to determine a master plan for regional flood control management.

• Journal of Korea Water Resources Association
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• v.43 no.12
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• pp.1051-1061
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• 2010

This study hydrologically re-analysed the Muskingum channel routing method to represent it as a linear combination of the linear channel model considering only the translation and the linear reservoir model considering only the storage effect. The resulting model becomes a kind of instantaneous unit hydrograph, whose parameters are identical to those of the Muskingum model. That is, the outflow occurs after the routing interval ${\Delta}t$ or concentration time $T_c$, and among the total amount of inflow, the x portion is translated by the linear channel model and the remaining (1-x) portion is routed by the linear reservoir model with the storage coefficient ��$K_c$. The application result of both the Muskingum channel routing method and its corresponding instantaneous unit hydrograph to an imaginary channel showed that these two models are basically identical. This result was also assured by the application to the channel flood routing to the Kumnam and Gongju Station for the discharge from the Daechung Dam.

• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.2
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• pp.75-86
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• 1996

The formulas for estimating the constants of storage function model including K and TL for runoff analysis and a distributed storage function model are discussed in this study. First, the relations between parameters of the storage function model and the kinematic runoff model are theoretically examined, and then optimum constants of storage function model are obtained by the Standardized Davidson-Fletcher-Powell (SDFP) method. Through this analysis, theoretical formulas were obtained as $K = 0.63 {\alpha} KsB{^0.6}$ and $T_{L}=0.11 {\alpha} KsB{^0.6} r{^0.4} {_e}$, which are difficult to use practically because of the unclarified definition of shape factors. From a practical point of view, empirical formula were derived as $K=15.6{^0.3} {_m}$ and $T_{L}=2.1B{^0.36} {_m} {_e}/r{^0.4} {_e}$ for applied watersheds. The proposed formulas are verified for several recoded floods at a few points of watersheds. It is also found that the distributed storage function. can be applied to flood runoff analysis using the new formulas aboved mentioned.

• Journal of the Korean Institute of Gas
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• v.5 no.1
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• pp.60-72
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• 2001

This paper presents the user-interactive productivity analysis model based on material balance as well as deliverability equations equipped with EOS model to perform a productivity analysis for Gorae V structure, Donghae-1 gas field. This model is designed to be able to analyse the productivity in the case of reservoir contacting with the aquifer. Also, in order to investigate the effect of condensation on productions, condensation phenomenon is considered as an apparent skin effect in the computation of bottomhole pressure from average reservoir pressure. By utilizing the developed model, we investigate the productivity analysis for B2 layer of Garae V structure with the various production cases in volumetric and non­volumetric reservoirs that contact with aquifer. From the results in the case of 5500 MMSCF/year of production and reservoir-aquifer contacting angle 270$^{\circ}C$ with aquifer size of 10 times greater than reservoir, B2 layer could maintain peak production rate even after 8.5 years of production by considering the bottomhole pressure which is estimated above the operating pressure of 1298 psia. It is also found that condensate will be formed after 1100 days of production and existed throughout the reservoir at 1270 days. Note that the computed reservoir pressure of B2 layer is maintained sufficiently high enough for production due to the water influx into the reservoir, and skin effect caused by condensation is not significant.

• Journal of Korea Water Resources Association
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• v.46 no.6
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• pp.597-611
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• 2013

This paper presents the methodology for construction of time-area curve via the width function and thereby rational estimation of time of concentration and storage coefficient of Clark model within the framework of method of moments. To this end time-area curve is built by rescaling the grid-based width function under the assumption of pure translation and then the analytical expressions for two parameters of Clark model are proposed in terms of method of moments. The methodology in this study based on the analytical expressions mentioned before is compared with both (1) the traditional optimization method of Clark model provided by HEC-1 in which the symmetric time-area curve is used and the difference between observed and simulated hydrographs is minimized (2) and the same optimization method but replacing time-area curve with rescaled width function in respect of peak discharge and time to peak of simulated direct runoff hydrographs and their efficiency coefficient relative to the observed ones. The following points are worth of emphasizing: (1) The optimization method by HEC-1 with rescaled width function among others results in the parameters well reflecting the observed runoff hydrograph with respect to peak discharge coordinates and coefficient of efficiency; (2) For the better application of Clark model it is recommended to use the time-area curve capable of accounting for irregular drainage structure of a river basin such as rescaled width function instead of symmetric time-area curve by HEC-1; (3) Moment-based methodology with rescaled width function developed in this study also gives rise to satisfactory simulation results in terms of peak discharge coordinates and coefficient of efficiency. Especially the mean velocities estimated from this method, characterizing the translation effect of time-area curve, are well consistent with the field surveying results for the points of interest in this study; (4) It is confirmed that the moment-based methodology could be an effective tool for quantitative assessment of translation and storage effects of natural river basin; (5) The runoff hydrographs simulated by the moment-based methodology tend to be more right skewed relative to the observed ones and have lower peaks. It is inferred that this is due to consideration of only one mean velocity in the parameter estimation. Further research is required to combine the hydrodynamic heterogeneity between hillslope and channel network into the construction of time-area curve.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1491-1494
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• 2010

2000년 이후 국지성 호우로 인한 지역별 홍수량의 차이가 현저히 많이 나고 있다. 때문에 유역 내 주요시설물 및 인명피해를 줄이기 위해서는 유역의 특성을 최대한 반영한 홍수 분석이 필요하다. 본 연구에서는 충주댐 유역의 실측 강우량 및 유입량 자료를 이용하여 단위도를 유도하였다. 단위도 산정 방법은 강우자료의 모의기능을 추가한 Modified Clark 방법을 이용하였다. 단위도 관련 직접유출의 형태를 결정하는 주요 매개변수는 도달시간 $T_c$와 저류상수 K에 의하여 결정되며, 홍수량 산정 시 가장 중요한 매개변수라고 할 수 있다. 충주댐 유역의 2002년부터 2007년까지의 강우자료 중 대표 강우사상을 분리하여 강우사상별 매개변수를 추정하였다. 추정 결과 강우 사상별 형태에 따라 매개변수가 다르게 나타났다. 이는 강우의 패턴에 따라 댐에 유입되는 매개변수가 다르기 때문인 것으로 보인다.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.976-980
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• 2009

수자원분야에서 강우-유출의 해석은 홍수의 분석 및 수자원 이용의 측면에서 가장 중요한 문제이다. 유역의 물리적 특성이 반영된 정확한 홍수량의 산정을 위해 유역의 지형인자 및 수문모형의 매개변수 추출에 대한 연구가 폭넓게 진행되고 있다. 그러나 아직까지 이러한 방법들에 대한 명확한 기준은 정립되지 못한 상태이다. 본 연구에서는 소유역 분할에 따른 영향분석을 위해 단일유역과 다수유역으로 구분하였고, 대상유역의 소유역분할에 따른 유역면적, 유로연장, 경사 등의 매개변수를 산정하여 도달시간, 저류상수, CN 등을 결정하고, 홍수량 산정결과의 민감도 분석 및 검토를 수행하였다. 또한 유역별 하도에서의 직접도달시간과 최원점에서의 도달시간을 산정하는 경우로 구분하여 유로연장의 조건별 영향을 분석하였다. 분석결과 일정 유역분할 이후에는 유역분할이 유출모의 결과에 큰 영향을 미치지 않음을 알 수 있었고, 소유역 분할에 따른 홍수량 증가 영향과 유로연장의 조건별 영향이 크지 않음을 판단할 수 있었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.528-528
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• 2016

신뢰성 있는 수문순환모의를 위해서 다양한 수문모형이 사용되고 있다. 그 중 대표적인 수문모형인 강우-유출 모형은 유역에 발생한 강우에 반응하는 유출특성을 평가하는데 이용된다. 강우-유출 과정은 강우량, 유출량, 도달시간 및 토양수분 등과 연관된 매개변수들의 최적화 과정을 통해서 추정된다. 하지만 동일한 강우사상이라도 다양한 매개변수들로 인하여 상당히 다른 유출패턴을 나타내기 때문에 수문순환 과정을 정확히 모의하기 위해서 강우-유출 분석시 불확실성 분석이 필수적으로 요구된다. 불확실성 분석은 통계학에서도 쉽지 않은 연구내용으로서 가장 진보된 불확실성 분석기법인 Bayesian 기법은 매개변수의 추정과 불확실성 분석을 동시에 수행할 수 있는 방법으로 매개변수들은 사후분포(posterior distribution)로 귀결되며 최종적으로 확률분포형의 형태를 가진다. 본 연구에서는 국내외적으로 널리 사용되는 단기유출 모형 HEC-1 모형에 Bayesian 기법을 연계하여 대상유역의 도달시간, 저류상수 및 CN No. 최적화 및 불확실성 평가를 수행하였다. 연구결과 Bayesian 기법을 통한 매개변수 최적화 결과는 안정적인 수렴결과를 확인하였으며, 확률강우량을 입력자료로 사용하여 산정된 빈도별 홍수수분곡선의 불확실성 분석을 통하여 향후 수공구조물의 위험도 분석 및 수자원계획 수립시 유용한 자료로 사용될 것으로 판단된다.