• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.393-397
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• 2007

KModSim은 수자원배분에 관련된 물리적, 수문학적, 제도적, 그리고 행정적인 요구들을 동시에 만족하도록 디자인된 범용 우선순위 목적 선형최적화 모형으로써 자연유입량과 기득 수리권 혹은 기득 저류권 등과 같은 다양한 형태의 저수권 사이의 조화운영이 가능하다. KModSim 목적함수에 관련된 제약조건의 유연한 설정과 변경이 가능하며, 기존의 최적화 방법과 다르게 유역통합모의에 관련한 모형변수가 모형내에서 자동적으로 생성되도록 프로그램화 되어있다. 본 연구에서는 유역내 수자원의 효율적인 운영을 위하여 우선순위 목적 선형최적화 모형을 위한 Backrouting 방법을 개발하고 금강유역 일단위 KModSim 네트워크에 Backrouting 방법을 적용하여 적용성을 검토하였다. 금강유역에 KModSim을 적용하고 모의한 결과 Backrouting 방법을 사용한 모의결과가 Backrouting 방법을 사용하지 않은 경우에 비해 실측치를 보다 잘 재현하는 것으로 나타났다. 본 연구에서 개발된 Backrouting 방법은 다중목적 우선순위 선형최적화 모형을 이용하여 일단위 모의 시에 발생할 수 있는 과도한 손실을 방지하고자 할 때 적용할 수 있을 것으로 기대된다.

• Journal of Korea Water Resources Association
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• v.30 no.2
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• pp.131-141
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• 1997

In this study, the Storage Function Method and Loopnet Model (Unsteady flow analysis model) were used to construct the flood prediction system which can predict the effects of the water release in the downstream region of Teachong Dam. The regional frequency analysis (L-moment) was applied to compute frequency-based precipitation, and the flood prediction system was also used for flood routing of the down stream region of Teachong Dam in the Kum River Basin to calculate frequency based flood. The magnitude of flood, water level, discharge, and travel time to the major points of the downstream region of Teachong Dam, which can be used as an imdex of flood control management of Teachong Dam, were calculated.

• Journal of Wetlands Research
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• v.11 no.2
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• pp.107-121
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• 2009

Many rainfall-runoff models have been used for the flood forecasting. However, the determination of rainfall-runoff model parameters is very difficult. In this study, we investigated the efficiency of flood forecasting models by studying the optimization techniques for parameter calibration of SFM, Tank, and SSARR models. We analyzed the correlations between parameters in optimization techniques, then classified the parameters into parameter groups. For this we applied the sequential calibration method through the sensitivity analysis. As the results of the analysis, the parameter groups clibration method showed better result for peak flow and clibtation time.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.375-375
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• 2019

충주댐 유역의 미계측유역을 대상으로 공간분포를 고려한 저류함수법 기반의 유출자료를 활용하여 지역최대홍수량의 추정 가능성을 평가하였다. 유출자료의 공간확장 가능성을 보기위해 2008년부터 2017년까지의 홍수 사상 중에 8개를 선정하였으며, 적절한 비교와 NSE 검증을 위해 충주댐, 영월1, 영춘 수위관측소를 검정지점으로 지정하였다. 또한, 선정한 사상 8개의 계측유역 유출자료를 바탕으로 공간확장방법을 활용하여 미계측유역의 유출자료를 생성하였다. 생성한 유출자료로 충주댐 유역의 홍수 사상과 지역최대홍수량(QRMF) 사이의 상관관계를 분석하여 지역최대홍수량의 발생 가능성과 충주댐 유역의 K값을 추정하였다. NSE 검증결과 유역출구지점인 충주댐에서 0.53으로 만족하여 유출자료 공간확장방법을 활용한 모의유출자료 산정은 적절한 것으로 나타났으며, 모의유출자료의 특성이 실제 유역의 특성과 유사한 것으로 나타났다. 생성한 유출자료와 지역최대 홍수량($Q_{RMF}$)에 대해 피어슨 상관계수와 RMSE를 활용하여 평가한 결과 서로 매우 높은 상관관계를 나타냈으며(Pearson's r> 0.9), 홍수량 산정방법에 있어서 지역최대홍수량($Q_{RMF}$)를 사용하여 산정하는 것이 바람직한 것으로 나타났다(RMSE=1.94). 또한, 충주댐 유역에 대한 지역최대홍수량($Q_{RMF}$)의 K값은 5.298로 산출되었으며, 산출한 K값으로 전체적인 충주댐 유역의 최대홍수량뿐만 아니라 면적이 비교적 작은 소유역의 최대홍수량도 추정할 수 있었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.177-177
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• 2018

유역의 홍수량 산정하기 위해서 데이터기반 모형, 개념적 모형, 프로세스 기반 모형과 같은 다양한 개념의 수문학적 모형이 개발되고 적용성이 검토되고 있다. 물리기반 강우-유출관계 모형의 경우, 이론적으로 강우유출응답의 연속 모의에 적합하다고 알려져 있으나 모형 구성에 필요한 수문자료 확보의 한계성 때문에 실절적인 적용에 어려움이 있다. 또한 수문 자료가 충분하지 않거나, 없는 미계측 유역에서 홍수량을 산정하기 위해서는 기존의 수문 관측 시스템의 데이터를 이용하기 어렵기 때문에 레이더 및 위성 등을 이용한 다양한 기상수문데이터 도입이 필요하다. 이에 본 연구에서는 관측된 자료와 함께 모델기반 수문기상 시스템인 GLDAS(Global Land Data Assimilation System, GLDAS)의 자료를 이용하여 개념적 강우-유출관계 모형인 PMD(Probaility Distributed Model, PMD)을 통해 홍수량을 모의하는 방법을 적용하였다. 이를 위해 개념적 강우유출관계 모형을 구성하고, 공간적 토양저류(soil moisture storage)분포를 산정하기 위해 토양의 함수상태를 산출하였다. 이같은 접근법은 수문 자료의 제한, 모형 검정의 문제와 같은 어려움을 해결하기 위한 대안으로 제시할 수 있으며, 분석 결과로부터 모델기반 수문기상 자료와 개념적 강우-유출관계 모형의 활용가능성을 검증할 계획이다.

• Geophysics and Geophysical Exploration
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• v.13 no.1
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• pp.80-87
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• 2010

This study was conducted to develop a reservoir modelling workflow to reproduce the heterogeneous distribution of effective permeability that impacts on the performance of SAGD (Steam Assisted Gravity Drainage), the in-situ bitumen recovery technique in the Athabasca Oil Sands. Lithologic facies distribution is the main cause of the heterogeneity in bitumen reservoirs in the study area. The target formation consists of sand with mudstone facies in a fluvial-to-estuary channel system, where the mudstone interrupts fluid flow and reduces effective permeability. In this study, the lithologic facies is classified into three classes having different characteristics of effective permeability, depending on the shapes of mudstones. The reservoir modelling workflow of this study consists of two main modules; facies modelling and permeability modelling. The facies modelling provides an identification of the three lithologic facies, using a stochastic approach, which mainly control the effective permeability. The permeability modelling populates mudstone volume fraction first, then transforms it into effective permeability. A series of flow simulations applied to mini-models of the lithologic facies obtains the transformation functions of the mudstone volume fraction into the effective permeability. Seismic data contribute to the facies modelling via providing prior probability of facies, which is incorporated in the facies models by geostatistical techniques. In particular, this study employs a probabilistic neural network utilising multiple seismic attributes in facies prediction that improves the prior probability of facies. The result of using the improved prior probability in facies modelling is compared to the conventional method using a single seismic attribute to demonstrate the improvement in the facies discrimination. Using P-wave velocity in combination with density in the multiple seismic attributes is the essence of the improved facies discrimination. This paper also discusses sand matrix porosity that makes P-wave velocity differ between the different facies in the study area, where the sand matrix porosity is uniquely evaluated using log-derived porosity, P-wave velocity and photographically-predicted mudstone volume.

• Journal of Korea Water Resources Association
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• v.52 no.9
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• pp.615-626
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• 2019

Soil moisture and runoff have very close relationship. Especially the water retention capacity and drainage characteristics of the soil are determined by various factors of the soil. In this study, a total of 40 rainfall events were identified from the entire rainfall events of Sulma basin in 2016 and 2017. For each selected events, the constant-K method was used to separate direct runoff and baseflow from total flow and calculate the runoff coefficient which shows positive exponential curve with Antecedent Soil Moisture (ASM). In addition to that, the threshold of soil moisture was determined at the point where the runoff coefficient starts increasing dramatically. The threshold of soil moisture shows great correlation with runoff and depth to water table. It was founded that not only ASM but also various factors, such as Initial Soil Moisture (ISM), storage capacity of soil and precipitation, affect the results of runoff response. Furthermore, wet condition and dry condition are separated by ASM threshold and the start and peak response are analyzed. And the results show that the response under wet condition occurred more quickly than that of dry condition. In most events occurred in dry condition, factors reached peak in order of soil moisture, depth to water table and runoff. However, in wet condition, they reached peak in order of depth to water table, runoff and soil moisture. These results will help identify the interaction among factors which affect the runoff, and it will help establish the relationship between various soil conditions and runoff.

• Journal of the Korean Institute of Gas
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• v.17 no.2
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• pp.59-69
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• 2013

This study presents development of the ANN simulator for well placement of infill drilling in gas fields. The input data of the ANN simulator includes the production time, well location, all inter well distances, boundary inter well distance, infill well position, productivity potential, functional links, reservoir pressure. The output data includes the bottomhole pressure in addition to the production rate. Thus, it is possible to calculate the productivity and bottomhole pressure during production period simultaneously, and it is expected that this model could replace conventional simulators. Training for the 20 well placement scenarios was conducted. As a result, it was found that accuracy of ANN simulator was high as the coefficient of correlation for production rate was 0.99 and the bottomhole pressure 0.98 respectively. From the resultes, the validity of the ANN simulator has been verified. The term, which could produce Maximum Daily Quantity (MDQ) at the gas field and the productivity according to the well location was analyzed. As a result, the MDQ could be maintained for a short time in scenario C-1, which has the three infill wells nearby aquifer boundary, and a long time in scenario A-1. In conclusion, it was found that scenario A maintained the MDQ up to 21% more than those of scenarios B and C which include parameters that might affect the productivity. Thus, the production rate can be maximized by selecting the location of production wells in comprehensive consideration of parameters that may affect the productivity. Also, because the developed ANN simulator could calculate both production rate and bottomhole pressure, respectively, it could be used as the forward simulator in a various inverse model.

• Water for future
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• v.26 no.1
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• pp.93-101
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• 1993

Because of the Keumkangsan-Dam and the Peace-Dam constructed in recent years, it is expected that the peak flood discharge and the peak flood stage at the Hwachun-Dam site have been changed. In this study, two methods were used to simulate and compare the effects of the upstream dam construction on the change of the discharge and the stage. One is the storage function method widely used for the hydrological routing in this country. The other is the DWOPER (Dynamic Wave Operational Model) package developed by the U.S. NWS for the hydraulic routing. Flood routing simulations have been performed on four different scenarios:1) Before the construction of the Keumkangsan-Dam and the peace-Dam, 2) The exclusion of the Keumkangsan-Dam watershed (before the construction of the Peace-Dam), 3) The exclusion of the Keumkangsan-Dam watershed (after the construction of the Peace-Dam), 4) The exclusion of the Peace-Dam watershed. The results of the four test cases from the two methods show that the peak flood discharge and the peak flood stage at the Hwachun-Dam site are reduced due to the construction of the Peace-Dam. From these findings, it is suggested that the operational criteria for the optimal dam-operation of the hwachun-Dam need to be modified.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.3
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• pp.171-182
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• 2006

In this study, rainfall-runoff analysis was performed for Yongdam watershed($930km^2$) using KOWACO flood analysis model based on Storage Function Method as lumped hydrologic model and Vflo which was developed for real-time flood prediction by University of Oklahoma. The results shows that, the hydrographs of lumped and distributed model with uncalibrated parameters which estimated from physical or experimental relationship show significant biases from observed hydrographs. However, the hydrograph at Cheoncheon site from the distributed model follows the actual hydrograph to an extent that no more calibration is necessary. It encourages that distributed model can have advantages for application in real-time flood forecasting as physically based distributed hydrologic model which can construct event-independent basin parameter group.